Separations

19 pages, 13378 KB

Open AccessEditor’s ChoiceArticle

Semi-Pilot Scale Extraction of Pinocembrin and Galangin from Populus alba L. × berolinensis K. Koch via Enzymatic Pretreatment and Ultrasonication

by Ru Zhao, Xiaoli Li, Yazhou Bao, Wenjun Xu, Chen Xu, Rongrong Wang, Tianlan Xia, Tingli Liu and Ailing Ben

Separations 2025, 12(9), 249; https://doi.org/10.3390/separations12090249 - 11 Sep 2025

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Abstract

In this investigation, pinocembrin and galangin were efficiently extracted from the male inflorescence of Populus alba L. × berolinensis K. Koch through an enzymatic pretreatment–ultrasonic-assisted strategy (EP-UAS), and the feasibility of their pilot-scale application was validated. The optimal parameters (ethanol volume fraction, cellulase [...] Read more.

In this investigation, pinocembrin and galangin were efficiently extracted from the male inflorescence of Populus alba L. × berolinensis K. Koch through an enzymatic pretreatment–ultrasonic-assisted strategy (EP-UAS), and the feasibility of their pilot-scale application was validated. The optimal parameters (ethanol volume fraction, cellulase dosage, incubation temperature, incubation time, pH, liquid‒solid ratio, ultrasonic irradiation power during incubation, duty cycle, ultrasonic irradiation power and time during extraction) affecting pinocembrin and galangin yields were systematically explored. The Box–Behnken design (BBD) results provided optimal parameters for the EP-UAS process. Under the optimal conditions, the actual yields of pinocembrin and galangin were 2158.33 ± 0.13 μg/g and 1257.96 ± 0.06 μg/g, respectively. Stability, recovery and reproducibility were determined under the above optimized conditions to evaluate the proposed EP-UAS method. Moreover, laboratory-scale experimental results revealed that the conditions selected via single-factor and response surface experiments were also applicable to pilot-scale production, facilitating industrialization. Full article

(This article belongs to the Special Issue Green Extraction Techniques for Bioactive Products from Natural Sources)

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14 pages, 4696 KB

Open AccessEditor’s ChoiceArticle

Efficient Photocatalytic Reduction of Cr(VI) on N-Doped Sludge/Cellulose-Derived Porous Carbon Using Synergistic Experimental–Deep Learning Approach

by Na Huang, Shengwen Chen and Wanhe Du

Separations 2025, 12(9), 247; https://doi.org/10.3390/separations12090247 - 9 Sep 2025

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Abstract

The photocatalytic reduction of hexavalent chromium (Cr(VI)) in wastewater represents a critical environmental challenge, given its high toxicity and mobility in wastewater. Conventional optimization methods relying on repetitive batch experiments with excessive reagent consumption. Herein, we proposed a synergistic experimental–deep learning approach to [...] Read more.

The photocatalytic reduction of hexavalent chromium (Cr(VI)) in wastewater represents a critical environmental challenge, given its high toxicity and mobility in wastewater. Conventional optimization methods relying on repetitive batch experiments with excessive reagent consumption. Herein, we proposed a synergistic experimental–deep learning approach to realize efficient photocatalytic reduction of Cr(VI). Sludge and cellulose precursors were used to prepare N-doped porous carbon through a green fabrication method at low temperature. After optimizing the composition and experimental factors, the removal efficiency of Cr(VI) could reach 92.7% after visible light irradiation in an acidic environment. The high efficiency originated from the coupled adsorption and photocatalytic mechanism. Innovatively, after comparing three algorithms, TCN and Transformer were employed to predict the desirable removal efficiency with <5% prediction error under different reaction conditions. This work highlights the novel experimental–deep learning method for heavy metal remediation using N-doped waste-derived porous carbon. Full article

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22 pages, 7600 KB

Open AccessEditor’s ChoiceArticle

Experimental Study on Spatiotemporal Evolution Mechanisms of Roll Waves and Their Impact on Particle Separation Behavior in Spiral Concentrators

by Jian Wang, Huizhong Liu, Qihua Zou and Jun Hu

Separations 2025, 12(9), 245; https://doi.org/10.3390/separations12090245 - 8 Sep 2025

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Abstract

Spiral concentrators are gravity and centrifugal force-based devices designed for mineral concentration. During processing operations, dynamic variations in the slurry’s liquid film thickness can induce hydrodynamic instability, generating roll waves on the free surface that compromise particle separation efficiency. To ensure operational stability [...] Read more.

Spiral concentrators are gravity and centrifugal force-based devices designed for mineral concentration. During processing operations, dynamic variations in the slurry’s liquid film thickness can induce hydrodynamic instability, generating roll waves on the free surface that compromise particle separation efficiency. To ensure operational stability and efficacy, this study establishes a theoretical shallow-water flow model for slurry dynamics in spiral concentrators based on hydraulic principles. Through L₂₇(3¹³) orthogonal experiments and real-time ultrasonic film thickness monitoring, the influence of key parameters on roll wave evolution is quantified. Results indicate that roll waves follow an “instability-development-dissipation” sequence. The pitch-to-diameter ratio (P/D) exerts a highly significant effect on roll wave intensity, while particle properties (density and size) exhibit moderate significance. In contrast, feed flow rate and solid concentration show negligible impacts. Roll waves amplify fluid turbulence, triggering stochastic migration of particles (especially low-density grains), which increases the standard deviation of zonal recovery rates (ZRR) and degrades separation precision. This work provides critical insights into particle behavior under roll wave conditions and offers a theoretical foundation for optimizing spiral concentrator design and process control. Full article

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21 pages, 3693 KB

Open AccessEditor’s ChoiceArticle

Electrochemistry–Mass Spectrometry for Generation and Identification of Metabolites of Selected Drugs from Different Therapeutic Groups in Comparison with In Vitro and In Vivo Approaches

by Małgorzata Szultka-Młyńska

Separations 2025, 12(9), 243; https://doi.org/10.3390/separations12090243 - 5 Sep 2025

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Abstract

The metabolism of antibiotics, antidepressants, and cardiovascular drugs has been investigated widely over the last few decades. The aim of this study was to develop an efficient analytical protocol based on the combination of electrochemistry (EC) and mass spectrometry for the identification of [...] Read more.

The metabolism of antibiotics, antidepressants, and cardiovascular drugs has been investigated widely over the last few decades. The aim of this study was to develop an efficient analytical protocol based on the combination of electrochemistry (EC) and mass spectrometry for the identification of electrochemical products (potential pharmacologically active metabolites) of selected drugs (enalapril, metronidazole, midazolam, propranolol, venlafaxine). The electrochemical mimicry of the oxidative phase I and II metabolism was achieved in a thin-layer cell equipped with different working electrodes (magic diamond (MD), glassy carbon (GC), gold (Au), platinum (Pt)). The structures of the electrochemically generated metabolites were elucidated based on accurate mass ion data and tandem mass spectrometry (MS/MS) experiments. The in silico prediction of the main sites of selected drugs’ metabolism was performed using Biotransformer 3.0, GLORYx, and Xenosite software. Moreover, incubation with liver microsomes (LMs) was performed to examine the proposed metabolic pathways of target compounds. The data from in vitro experiments agreed with the data from electrochemical oxidation, which predicted some potential metabolites found in the real samples from patients. For enzymatic incubation, N-dealkylation, O-demethylation, and hydroxylation were the metabolic pathways involved mainly in their metabolism. Their in vitro phase II metabolites were identified as glucuronic acid conjugates. Finally, different in vivo phase I and II metabolites were identified for the studied drugs, including metabolic pathways for in vivo phase I N-demethylation, N-dealkylation, O-demethylation, and hydroxylation, while the metabolic pathways for in vivo phase II metabolites were identified as glucuronic acid conjugates. Full article

(This article belongs to the Special Issue Separation Techniques in Drug Analysis)

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18 pages, 4673 KB

Open AccessEditor’s ChoiceArticle

Effect of Iron–Carbon–Zeolite Substrate Configuration on Cadmium Removal in Vertical-Flow Constructed Wetlands

by Mengyi Li, Shiyu Chen, Jundan Chen, Naifu Zhou and Guanlong Yu

Separations 2025, 12(8), 223; https://doi.org/10.3390/separations12080223 - 21 Aug 2025

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Abstract

The excessive emission of cadmium (Cd²⁺) poses a serious threat to the aquatic environment due to its high toxicity and bioaccumulation potential. This study constructed three types of vertical-subsurface-flow constructed wetlands configured with iron–carbon–zeolite composite substrates, including an iron–carbon–zeolite constructed wetland [...] Read more.

The excessive emission of cadmium (Cd²⁺) poses a serious threat to the aquatic environment due to its high toxicity and bioaccumulation potential. This study constructed three types of vertical-subsurface-flow constructed wetlands configured with iron–carbon–zeolite composite substrates, including an iron–carbon–zeolite constructed wetland (TF-CW), a zeolite–iron–carbon constructed wetland (FT-CW), and an iron–carbon–zeolite mixed constructed wetland (H-CW), to investigate the purification performance and mechanisms of constructed wetlands for cadmium-containing wastewater (0~6 mg/L). The results demonstrated that iron–carbon–zeolite composite substrates significantly enhanced Cd²⁺ removal efficiency (>99%) through synergistic redox-adsorption mechanisms, where the iron–carbon substrate layer dominated Fe-Cd co-precipitation, while the zeolite layer achieved short-term cadmium retention through ion-exchange adsorption. FT-CW exhibited superior NH₄⁺-N removal efficiency (77.66%~92.23%) compared with TF-CW (71.45%~88.05%), while iron–carbon micro-electrolysis effectively inhibited NO₃⁻-N accumulation (<0.1 mg/L). Under cadmium stress, Typha primarily accumulated cadmium through its root systems (>85%) and alleviated oxidative damage by dynamically regulating antioxidative enzyme activity, with the superoxide dismutase (SOD) peak occurring at 3 mg/L Cd²⁺ treatment. Microbial community analysis revealed that iron–carbon substrates promoted the relative abundance of Bacteroidota and Patescibacteria as well as the enrichment of Saccharimonadales, Thauera, and Rhodocyclaceae (genera), enhancing system stability. This study confirms that iron–carbon–zeolite CWs provide an efficient and sustainable technological pathway for heavy metal-contaminated water remediation through multidimensional mechanisms of “chemical immobilization–plant enrichment–microbial metabolism”. Full article

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12 pages, 1561 KB

Open AccessEditor’s ChoiceArticle

Effect of Performance and Fouling Mechanisms of Thermo-Responsive Membranes on Treating Secondary Effluent Containing Added Sulfamethoxazole

by Lian Yang, Haoran Qiu, Yingjie Yang, Lijun Zhao, Ping Xiao, Guoliang Liu, Jiang Chang, Shaoxia Yang and Feng Xiao

Separations 2025, 12(8), 218; https://doi.org/10.3390/separations12080218 - 16 Aug 2025

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Abstract

Wastewater treatment plants generally lack a specialized design for the efficient removal of sulfamethoxazole (SMX), a toxic and bio-resistant compound. In this study, secondary effluent from a Beijing wastewater reclamation treatment plant was spiked with SMX and used to investigate the filtration performance [...] Read more.

Wastewater treatment plants generally lack a specialized design for the efficient removal of sulfamethoxazole (SMX), a toxic and bio-resistant compound. In this study, secondary effluent from a Beijing wastewater reclamation treatment plant was spiked with SMX and used to investigate the filtration performance and fouling mechanisms of thermo-responsive membranes. Thermo-responsive materials were prepared using polyvinylidene fluoride, N-isopropylacrylamide (NIPAM), and graphene oxide through Ce (IV)-induced redox radical polymerization. The results showed that the removal of SMX and COD reached 42% and 92%, respectively, with a NIPAM dosage of 1 g, and the removal of UV₂₅₄ reached its highest value at 57.9%. Additionally, the filtration flux was higher at a temperature of 35 °C with a NIPAM dosage of 1 g. The fluorescence intensity of the organic matter from the secondary effluent spiked with SMX and decreased after the thermo-responsive membranes were implemented, and filtration with the membrane containing 1 g of NIPAM achieved a lower intensity at a value of 3074.6, according to the analysis of three-dimensional fluorescence excitation–emission spectroscopy. According to the extended Derjaguin–Laudau–Verwey–Overbeek theory analysis, the interfacial free energies of the thermo-responsive membrane with a 1 g dose of NIPAM were higher than the others during filtration. Full article

(This article belongs to the Special Issue Application of Adsorption and Separation Technologies in Water Treatment)

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28 pages, 10833 KB

Open AccessEditor’s ChoiceArticle

Optimization and Component Identification of Ultrasound-Assisted Extraction of Polyphenols from Coriander (Coriandrum sativum L.) and Evaluation of Polyphenol Content Changes and Antioxidant Activity During Storage

by Heng Yuan, Chunzhi Xie, Yue Ma, Yaqi Miao, Xuehong Chen, Hao Gong and Jun Wang

Separations 2025, 12(8), 217; https://doi.org/10.3390/separations12080217 - 16 Aug 2025

Cited by 1 | Viewed by 475

Abstract

Coriander (Coriandrum sativum L.) has significant value in the food industry due to its unique flavor and health benefits. However, its polyphenol content and antioxidant activity have not been systematically analyzed during storage. This study optimized the extraction process of coriander polyphenols [...] Read more.

Coriander (Coriandrum sativum L.) has significant value in the food industry due to its unique flavor and health benefits. However, its polyphenol content and antioxidant activity have not been systematically analyzed during storage. This study optimized the extraction process of coriander polyphenols using ultrasound-assisted extraction combined with response surface methodology. The polyphenol composition was systematically identified, and changes in polyphenol content and antioxidant activity during storage were investigated. The optimal process conditions for extracting coriander polyphenols were determined as 40% ethanol concentration, 1:121 g/mL material-to-liquid ratio, 81 °C extraction temperature, and 10 min extraction time. This optimized protocol yielded 16.231 mg GAE/g, a 119.28% increase over conventional methods using the same raw material. Fifty polyphenolic compounds were identified using high-resolution mass spectrometry. The main types of polyphenols identified were quercetin, kaempferol, and hydroxycinnamic acid derivatives. Notably, 41 of these compounds were reported in coriander for the first time. In vitro tests revealed that coriander polyphenols exhibit potent antioxidant properties, with IC₅₀ values of 73.43 μg/mL for DPPH and 82.15 μg/mL for ABTS. Furthermore, the polyphenol content and antioxidant capacity of coriander increased significantly during storage, with total phenolic content rising by 40.5%, DPPH activity by 32.5%, and ABTS activity by 56.5%. Key individual polyphenols showed differential changes: rutin continuously accumulated, while chlorogenic acid and ferulic acid exhibited an initial increase followed by a decrease. This study provides strong technical support for the use of coriander polyphenols in functional foods and medicines. Full article

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17 pages, 3206 KB

Open AccessEditor’s ChoiceArticle

Inverse Punicines: Isomers of Punicine and Their Application in LiAlO₂, Melilite and CaSiO₃ Separation

by Maximilian H. Fischer, Ali Zgheib, Iliass El Hraoui, Alena Schnickmann, Thomas Schirmer, Gunnar Jeschke and Andreas Schmidt

Separations 2025, 12(8), 202; https://doi.org/10.3390/separations12080202 - 30 Jul 2025

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Abstract

The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. [...] Read more.

The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. These amphoteric molecules were synthesized via a straightforward four-step route and structurally tuned for hydrophobization by alkylation. Their performance as collectors was evaluated in microflotation experiments of lithium aluminate (LiAlO₂) and silicate matrix minerals such as melilite and calcium silicate. Characterization techniques including ultraviolet-visible (UV-Vis), nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy as well as contact angle, zeta potential (ζ potential) and microflotation experiments revealed strong pH- and structure-dependent interactions with mineral surfaces. Notably, N-alkylated inverse Punicine derivatives showed high flotation yields for LiAlO₂ at pH of 11, with a derivative possessing a dodecyl group attached to the nitrogen as collector achieving up to 86% recovery (collector conc. 0.06 mmol/L). Preliminary separation tests showed Li upgrading from 5.27% to 6.95%. Radical formation and light-response behavior were confirmed by ESR and flotation tests under different illumination conditions. These results demonstrate the potential of inverse Punicines as tunable, sustainable flotation reagents for advanced lithium recycling from complex slag systems. Full article

(This article belongs to the Special Issue Application of Green Flotation Technology in Mineral Processing)

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27 pages, 1893 KB

Open AccessEditor’s ChoiceArticle

Separating 2-Propanol and Water: A Comparative Study of Extractive Distillation, Salting-Out, and Extraction

by Aleksandra Sander, Marko Rogošić, Leonarda Frljak, Daniela Vasiljević, Iva Blažević and Jelena Parlov Vuković

Separations 2025, 12(8), 196; https://doi.org/10.3390/separations12080196 - 26 Jul 2025

Cited by 1 | Viewed by 942

Abstract

Separating azeotropes is an important, difficult, and expensive task, in particular for the 2-propanol–water mixture. The literature on the problem is rich in modeling studies but often lacking even the simplest experimental confirmation. In this paper, extractive distillation, liquid–liquid equilibrium-based extraction, and salting-out [...] Read more.

Separating azeotropes is an important, difficult, and expensive task, in particular for the 2-propanol–water mixture. The literature on the problem is rich in modeling studies but often lacking even the simplest experimental confirmation. In this paper, extractive distillation, liquid–liquid equilibrium-based extraction, and salting-out were experimentally tested for the desired separation. Among the four tested extractive distillation entrainers, none was able—in the investigated experimental setup—to push the system over the azeotropic composition threshold. Four novel hydrophobic deep eutectic extraction media were tested for the desired separation, and those based on menthol or thymol with decanoic acid were found most promising. Among 16 tested salting-out agents, 5 of them produced two-liquid phases, and only 4 hydrophilic inorganic salts promoted 2-propanol separation, with sodium carbonate being the most promising candidate. The purity of the products was tested with FTIR and ¹H-NMR. The experimental findings were compared with COSMO-RS model predictions, with moderate success. Full article

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14 pages, 4700 KB

Open AccessEditor’s ChoiceArticle

Pilot-Scale Phycocyanin Extraction by the Green Two-Step Ultrasound-Based UltraBlu Process

by Rosaria Lauceri, Melissa Pignataro, Antonio Giorgi, Antonio Idà and Lyudmila Kamburska

Separations 2025, 12(8), 194; https://doi.org/10.3390/separations12080194 - 25 Jul 2025

Viewed by 459

Abstract

Phycocyanin is a natural, non-toxic, blue pigment-protein with many commercial applications. Its exploitation in various biotechnological sectors strongly depends on its purity grade (P). Phycocyanin is largely used in food industry where a low purity grade is required, while its widespread use in [...] Read more.

Phycocyanin is a natural, non-toxic, blue pigment-protein with many commercial applications. Its exploitation in various biotechnological sectors strongly depends on its purity grade (P). Phycocyanin is largely used in food industry where a low purity grade is required, while its widespread use in sectors requiring a higher purity is hampered by the cost of large-scale industrial production. Industry, in fact, needs simple, easily scalable and cost-effective procedures to ensure sustainable production of high-quality pigment. In this work we applied the innovative two-step ultrasound-based process UltraBlu to the pilot-scale production of phycocyanin. A total of 50 L of biomass suspension of commercial Spirulina were processed in batch mode. The pigment extract was obtained in one day, including the biomass harvesting. Food/cosmetic grade (P = 1.41–1.76) and a good yield (Y = 59.2–76.1%) were achieved. The initial results obtained suggest that UltraBlu can be an effective scalable process suitable to produce phycocyanin also on an industrial scale. Full article

(This article belongs to the Special Issue Application of Sustainable Separation Techniques in Food Processing)

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11 pages, 1292 KB

Open AccessEditor’s ChoiceArticle

Flotation Behaviours of Ilmenite and Associated Solution Chemistry Properties Using Saturated Fatty Acids as the Collector

by Jihua Zhai, Hao He, Pan Chen, Lin Song, Xiaohai Yao and Hongxian Zhang

Separations 2025, 12(8), 191; https://doi.org/10.3390/separations12080191 - 24 Jul 2025

Cited by 1 | Viewed by 356

Abstract

A series of homologous saturated fatty acids were introduced and evaluated as collectors for ilmenite flotation using a combination of micro-flotation tests and surface tension measurements. The results showed that ilmenite exhibited good flotation behaviour when decanoic and dodecanoic acids were used as [...] Read more.

A series of homologous saturated fatty acids were introduced and evaluated as collectors for ilmenite flotation using a combination of micro-flotation tests and surface tension measurements. The results showed that ilmenite exhibited good flotation behaviour when decanoic and dodecanoic acids were used as collectors; however, saturated fatty acids with shorter or longer carbon chains were not suitable for ilmenite flotation (caused either by poor collection ability or limited solubility in water). The optimum flotation pH range was also dependent on the carbon chain length of saturated fatty acids, and the solution surface tension did not always match well with the ilmenite flotation behaviour when using a series of saturated fatty acids as the collector. The associated solution chemistry properties under series saturated fatty acid flotation systems were discussed, and the adsorption mechanism of decanoic acid onto the ilmenite surface was also investigated via FTIR, zeta potential, and contact angle measurements. Full article

(This article belongs to the Section Separation Engineering)

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21 pages, 727 KB

Open AccessEditor’s ChoiceArticle

Seasonal and Cultivar-Dependent Phenolic Dynamics in Tuscan Olive Leaves: A Two-Year Study by HPLC-DAD-MS for Food By-Product Valorization

by Tommaso Ugolini, Lorenzo Cecchi, Graziano Sani, Irene Digiglio, Barbara Adinolfi, Leonardo Ciaccheri, Bruno Zanoni, Fabrizio Melani and Nadia Mulinacci

Separations 2025, 12(8), 192; https://doi.org/10.3390/separations12080192 - 24 Jul 2025

Cited by 2 | Viewed by 437

Abstract

Olive tree leaf is a phenol-rich, high-potential-value biomass that can be used to formulate food additives and supplements. Leaf phenolic content varies depending on numerous factors, like cultivar, geographical origin, year, and season of harvest. The aim of this research was to evaluate [...] Read more.

Olive tree leaf is a phenol-rich, high-potential-value biomass that can be used to formulate food additives and supplements. Leaf phenolic content varies depending on numerous factors, like cultivar, geographical origin, year, and season of harvest. The aim of this research was to evaluate the variations in phenolic profile of four major Tuscan cultivars (Frantoio, Leccio del Corno, Leccino, and Moraiolo) over four different phenological phases and across two years. All 96 olive leaf samples were harvested from trees grown in the same orchard located in Florence. After drying, their phenolic profile was characterized using HPLC-DAD-MS, and the obtained data were processed by ANOVA, GA-LDA, and RF methods. A total of 25 phenolic derivatives were analyzed, with total contents ranging 16,674.0–50,594.3 mg/kg and oleuropein (4570.0–27,547.7 mg/kg) being the predominant compound regardless of cultivar, year, and season of harvest. Oleuropein and hydroxytyrosol glucoside showed inverse proportionality and similar behavior across years in all cultivars, and therefore were highlighted as main phenolic compounds correlated with the seasonal variability in studied cultivars. Interesting behavior was also pointed out for apigenin rutinoside. Application of GA-LDA and RF methods allowed pointing out the excellent performance of leaf phenols in discriminating samples based on cultivar, harvest year, and harvesting season. Full article

(This article belongs to the Special Issue Extraction and Isolation of Nutraceuticals from Plant Foods)

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14 pages, 4274 KB

Open AccessEditor’s ChoiceArticle

The Role of Freezing Temperature in Modulating Chitosan Gel Structure and Evaporation Performance for Seawater Desalination

by Jiaonan Cai, Yong Bai and Fang Li

Separations 2025, 12(8), 193; https://doi.org/10.3390/separations12080193 - 24 Jul 2025

Viewed by 440

Abstract

Interfacial solar evaporation has emerged as a promising strategy for freshwater production, where 3D evaporators offer distinct advantages in heat management and salt rejection. Freeze–thaw cycling is a widely adopted fabrication method for 3D hydrogel evaporators, yet the impact of preparation conditions (e.g., [...] Read more.

Interfacial solar evaporation has emerged as a promising strategy for freshwater production, where 3D evaporators offer distinct advantages in heat management and salt rejection. Freeze–thaw cycling is a widely adopted fabrication method for 3D hydrogel evaporators, yet the impact of preparation conditions (e.g., freezing temperature) on their evaporation performance remains poorly understood, hindering rational optimization of fabrication protocols. Herein, we report the fabrication of chitosan-based hydrogel evaporators via freeze–thaw cycles at different freezing temperatures (−20 °C, −40 °C, and −80 °C), leveraging its low cost and environmental friendliness. Characterizations of crosslinking density and microstructure reveal a direct correlation between freezing temperature and network porosity, which significantly influences evaporation rate, photothermal conversion efficiency, and anti-salt performance. It is noteworthy that the chitosan hydrogel prepared at −80 °C demonstrates an excellent evaporation rate in high-salinity environments and exhibits superior salt resistance during continuous evaporation testing. Long-term cyclic experiments indicate that there was an average evaporation rate of 3.76 kg m⁻² h⁻¹ over 10 cycles, with only a 2.5% decrease observed in the 10th cycle. This work not only elucidates the structure–property relationship of freeze–thaw fabricated hydrogels but also provides a strategic guideline for tailoring evaporator architectures to different salinity conditions, bridging the gap between material design and practical seawater desalination. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Materials in Separation Science')

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14 pages, 1840 KB

Open AccessEditor’s ChoiceArticle

Volatilomic Fingerprint of Tomatoes by HS-SPME/GC-MS as a Suitable Analytical Platform for Authenticity Assessment Purposes

by Gonçalo Jasmins, Tânia Azevedo, José S. Câmara and Rosa Perestrelo

Separations 2025, 12(8), 188; https://doi.org/10.3390/separations12080188 - 22 Jul 2025

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Abstract

Tomatoes are globally esteemed not only for their nutritional value but also for their complex and appealing aroma, a key determinant of consumer preference. The present study aimed to comprehensively characterise the volatilomic fingerprints of three tomato species—Solanum lycopersicum L., S. lycopersicum [...] Read more.

Tomatoes are globally esteemed not only for their nutritional value but also for their complex and appealing aroma, a key determinant of consumer preference. The present study aimed to comprehensively characterise the volatilomic fingerprints of three tomato species—Solanum lycopersicum L., S. lycopersicum var. cerasiforme, and S. betaceum—encompassing six distinct varieties, through the application of headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC-MS). A total of 55 volatile organic compounds (VOCs) spanning multiple chemical classes were identified, of which only 28 were ubiquitously present across all varieties examined. Carbonyl compounds constituted the predominant chemical family, with hexanal and (E)-2-hexenal emerging as putative key contributors to the characteristic green and fresh olfactory notes. Notably, esters were found to dominate the unique volatile fingerprint of cherry tomatoes, particularly methyl 2-hydroxybenzoate, while Kumato and Roma varieties exhibited elevated levels of furanic compounds. Multivariate statistical analyses, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), demonstrated clear varietal discrimination and identified potential aroma-associated biomarkers such as phenylethyl alcohol, 3-methyl-1-butanol, hexanal, (E)-2-octenal, (E)-2-nonenal, and heptanal. Collectively, these findings underscore the utility of volatilomic fingerprint as a robust tool for varietal identification and quality control within the food industry. Full article

(This article belongs to the Special Issue Chromatography/Mass Spectrometry for the Determination of Food Authenticity and Food Analysis)

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19 pages, 735 KB

Open AccessEditor’s ChoiceReview

Nanoplastics: From Separations to Analysis—Challenges and Limitations

by Justyna Ośko, Kornelia Kadac-Czapska, Katarzyna Jażdżewska, Natalia Nowak, Piotr Kowalczyk and Małgorzata Grembecka

Separations 2025, 12(7), 185; https://doi.org/10.3390/separations12070185 - 15 Jul 2025

Cited by 1 | Viewed by 1322

Abstract

The issue of nanoplastics (NPs) in the environment, following that of microplastics (MPs), is receiving increasing attention in the scientific community. Due to their size, these particles require the development and application of new methods for both quantitative and qualitative determination. Consequently, techniques [...] Read more.

The issue of nanoplastics (NPs) in the environment, following that of microplastics (MPs), is receiving increasing attention in the scientific community. Due to their size, these particles require the development and application of new methods for both quantitative and qualitative determination. Consequently, techniques commonly used for analyzing MPs may prove ineffective in the context of NPs. Isolating NPs from samples with complex matrices poses a significant challenge that directly affects analytical outcomes. This paper aims to discuss the main challenges encountered during the analysis of NPs in environmental samples. Various methods for the visualization and identification of NPs are examined, with a focus on microscopic, spectroscopic, and thermal techniques. The advantages and limitations of analytical approaches reported in the literature are summarized, offering guidance for the future development and standardization of methods used to determine NPs in environmental contexts. Full article

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16 pages, 1369 KB

Open AccessEditor’s ChoiceArticle

Optimized Ethyl Chloroformate Derivatization Using a Box–Behnken Design for Gas Chromatography–Mass Spectrometry Quantification of Gallic Acid in Wine

by Sofia Botta, Roberta Piacentini, Chiara Cappelletti, Alessio Incocciati, Alberto Boffi, Alessandra Bonamore and Alberto Macone

Separations 2025, 12(7), 183; https://doi.org/10.3390/separations12070183 - 9 Jul 2025

Viewed by 522

Abstract

Gallic acid, a major phenolic compound in wine, significantly influences its sensory profile and health-related properties, making its accurate measurement essential for both enological and nutritional studies. In this context, a derivatization protocol for gallic acid using ethyl chloroformate (ECF) was developed and [...] Read more.

Gallic acid, a major phenolic compound in wine, significantly influences its sensory profile and health-related properties, making its accurate measurement essential for both enological and nutritional studies. In this context, a derivatization protocol for gallic acid using ethyl chloroformate (ECF) was developed and optimized for GC-MS analysis, with experimental conditions refined through a Box–Behnken Design (BBD). The BBD systematically investigated the effects of three critical reagent volumes: ethyl chloroformate, pyridine, and ethanol. This approach elucidated complex interactions and quadratic effects, leading to a predictive second-order polynomial model and identifying the optimal derivatization conditions for maximum yield (137 µL of ethyl chloroformate, 51 µL of pyridine, and 161 µL of ethanol per 150 µL of wine). The BBD-optimized GC-MS method was validated and successfully applied to quantify gallic acid in diverse commercial wine samples (white, red, conventional, natural). A key finding was the method’s wide dynamic range, enabling accurate quantification from 5 up to over 600 µg/mL without sample dilution. This work represents, to our knowledge, the first application of a BBD for optimizing the ethyl chloroformate derivatization of gallic acid, providing a robust, efficient, and widely applicable analytical tool for routine quality control and enological research. Full article

(This article belongs to the Special Issue Innovative Analytical Strategies Based on Mass Spectrometry in Food Analysis)

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22 pages, 1203 KB

Open AccessEditor’s ChoiceReview

Impact of Use of Ultrasound-Assisted Extraction on the Quality of Brazil Nut Oil (Bertholletia excelsa HBK)

by Orquidea Vasconcelos dos Santos, Sara Camila Vidal Freires, Helen Cristina de Oliveira Palheta and Paulo Henrique de Melo Ferreira

Separations 2025, 12(7), 182; https://doi.org/10.3390/separations12070182 - 8 Jul 2025

Cited by 1 | Viewed by 1219

Abstract

The quality of materials extracted from plant sources, such as oilseeds, is significantly affected by the extraction techniques employed. Thermo-photosensitive bioactive compounds are especially susceptible, often resulting in a loss of functional properties during conventional processing. In this context, studies involving unconventional or [...] Read more.

The quality of materials extracted from plant sources, such as oilseeds, is significantly affected by the extraction techniques employed. Thermo-photosensitive bioactive compounds are especially susceptible, often resulting in a loss of functional properties during conventional processing. In this context, studies involving unconventional or “innovative” extraction methods have emerged as a strategic approach to preserve the quality of the extracted material (whether by-product or biomass) by aligning with the core principles of green chemistry and the expansion of sustainable production chains. This approach promotes both raw material integrity and the protection of human and environmental health. These efforts contribute to a virtuous cycle of technological innovation and environmentally sound practices. This review focuses on how ultrasound-assisted extraction affects the quality of plant-derived materials, particularly Brazil nut oil. The article compiles data published over the last five years (2020–2025), following the PRISMA methodology. Recent studies highlight the synergistic potential of ultrasound as a green technology for isolating Brazil nut oil, offering enhanced nutritional and functional properties. This aligns with the growing demand for healthier food products obtained through sustainable industrial processes and presents opportunities for diverse applications across several industry sectors. Full article

(This article belongs to the Special Issue Extraction and Characterization of Food Components)

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12 pages, 2841 KB

Open AccessEditor’s ChoiceArticle

Extraction of Rubidium and Cesium Ions by Adsorption–Flotation Separation in Titanosilicate-Hexadecyltrimethylammonium Bromide System

by Dezhen Fang, Haining Liu, Xiushen Ye, Yanping Wang and Wenjie Han

Separations 2025, 12(7), 181; https://doi.org/10.3390/separations12070181 - 7 Jul 2025

Viewed by 460

Abstract

This study centers on the adsorption–flotation coupling extraction of rubidium (Rb⁺) and cesium (Cs⁺) within a titanium silicate (CTS)–cetyltrimethylammonium bromide (CTAB) system, systematically investigating the impacts of pH, aeration rate, CTAB concentration, and flotation time on the extraction efficiency [...] Read more.

This study centers on the adsorption–flotation coupling extraction of rubidium (Rb⁺) and cesium (Cs⁺) within a titanium silicate (CTS)–cetyltrimethylammonium bromide (CTAB) system, systematically investigating the impacts of pH, aeration rate, CTAB concentration, and flotation time on the extraction efficiency of these elements. Single-factor experiments revealed that the optimal flotation efficiency was achieved when the pH ranged from 6 to 10, the aeration rate was set at 1000 r/min, the CTAB concentration was 0.2 mmol/L, and the flotation duration was 18 min. Under these conditions, the adsorption capacities for Rb⁺ and Cs⁺ were recorded as 128.32 mg/g and 185.47 mg/g, respectively. Employing the response surface optimization method to analyze the interactive effects of these four factors, we found that their order of significance was as follows: pH > aeration rate > CTAB concentration > flotation time. The optimized parameters were determined as pH 8.64, bubble formation rate 1121 r/min, CTAB concentration 0.26 mmol/L, and flotation time 18.47 min. Under these refined conditions, the flotation efficiency for both CTS–Rb and CTS–Cs surpassed any single-factor experiment scenario, with the flotation efficiencies for Rb⁺ and Cs⁺ reaching 95.05% and 94.82%, respectively. This methodology effectively extracts Rb⁺ and Cs⁺ from low-concentration liquid systems, while addressing the challenges of solid–liquid separation for powdered adsorption materials. It holds significant theoretical and practical reference value for enhancing the separation processes of low-grade valuable components and boosting overall separation performance. Full article

(This article belongs to the Special Issue Green and Efficient Separation and Extraction of Salt Lake Resources)

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26 pages, 7085 KB

Open AccessEditor’s ChoiceReview

Advances in Electrolytic Manganese Residue: Harmless Treatment and Comprehensive Utilization

by Weijian Yu, Xiaoya Li, Wenting Xu, Qingjun Guan, Fujia Zhou, Jiani Zhang, Li Wang, Yanxiu Wang and Honghu Tang

Separations 2025, 12(7), 180; https://doi.org/10.3390/separations12070180 - 7 Jul 2025

Cited by 1 | Viewed by 715

Abstract

Electrolytic manganese residue (EMR) is a byproduct of electrolytic manganese production, rich in soluble pollutants such as manganese and ammonia nitrogen. Traditional stockpiling methods result in contaminant leaching and water pollution, threatening ecosystems. Meanwhile, EMR has significant resource-recovery potential. This paper systematically reviews [...] Read more.

Electrolytic manganese residue (EMR) is a byproduct of electrolytic manganese production, rich in soluble pollutants such as manganese and ammonia nitrogen. Traditional stockpiling methods result in contaminant leaching and water pollution, threatening ecosystems. Meanwhile, EMR has significant resource-recovery potential. This paper systematically reviews the harmless process and resource technology of EMR, efficiency bottlenecks, and the current status of industrial applications. The mechanisms of chemical leaching, precipitation, solidification, roasting, electrochemistry, and microorganisms were analyzed. Among these, electrochemical purification stands out for its efficiency and environmental benefits, positioning it as a promising option for broad industrial use. The mechanisms of chemical leaching, precipitation, solidification, roasting, electrochemistry, and microorganisms were analyzed, revealing the complementarity between building materials and chemical materials (microcrystalline glass) in scale and high-value-added production. But the lack of impurity separation accuracy and market standards restricts its promotion. Finally, it proposes future directions for EMR resource utilization based on practical and economic considerations. Full article

(This article belongs to the Special Issue Solid Waste Recycling and Strategic Metal Extraction)

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12 pages, 23410 KB

Open AccessEditor’s ChoiceArticle

Recycling and Separation of Valuable Metals from Spent Cathode Sheets by Single-Step Electrochemical Strategy

by Neng Wei, Yaqun He, Guangwen Zhang, Jiahao Li and Fengbin Zhang

Separations 2025, 12(7), 178; https://doi.org/10.3390/separations12070178 - 5 Jul 2025

Viewed by 472

Abstract

The conventional spent lithium-ion batteries (LIBs) recycling method suffers from complex processes and excessive chemical consumption. Hence, this study proposes an electrochemical strategy for achieving reductant-free leaching of high-valence transition metals and efficient separation of valuable components from spent cathode sheets (CSs). An [...] Read more.

The conventional spent lithium-ion batteries (LIBs) recycling method suffers from complex processes and excessive chemical consumption. Hence, this study proposes an electrochemical strategy for achieving reductant-free leaching of high-valence transition metals and efficient separation of valuable components from spent cathode sheets (CSs). An innovatively designed sandwich-structured electrochemical reactor achieved efficient reductive dissolution of cathode materials (CMs) while maintaining the structural integrity of aluminum (Al) foils in a dilute sulfuric acid system. Optimized current enabled leaching efficiencies exceeding 93% for lithium (Li), cobalt (Co), manganese (Mn), and nickel (Ni), with 88% metallic Al foil recovery via cathodic protection. Multi-scale characterization systematically elucidated metal valence evolution and interfacial reaction mechanisms, validating the technology’s tripartite innovation: simultaneous high metal extraction efficiency, high value-added Al foil recovery, and organic removal through single-step electrochemical treatment. The process synergized the dissolution of CM particles and hydrogen bubble-induced physical liberation to achieve clean separation of polyvinylidene difluoride (PVDF) and carbon black (CB) layers from Al foil substrates. This method eliminates crushing pretreatment, high-temperature reduction, and any other reductant consumption, establishing an environmentally friendly and efficient method of comprehensive recycling of battery materials. Full article

(This article belongs to the Special Issue Innovative Separation Techniques for Sustainable Recycling of Solid Waste)

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11 pages, 2330 KB

Open AccessEditor’s ChoiceArticle

Separations of Strategic Metals from Spent Electronic Waste Using “Green Methods”

by Urszula Domańska, Anna Wiśniewska and Zbigniew Dąbrowski

Separations 2025, 12(6), 167; https://doi.org/10.3390/separations12060167 - 18 Jun 2025

Viewed by 649

Abstract

Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing [...] Read more.

Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing additives that can overcome some traditional recycling methods of metal ions from e-waste, used in our works from last year, are presented. The unique chemical environments of ILs and DESs, with the application of low-temperature extraction procedures, are important environmental aspects known as “Green Methods”. A closed-loop system for recycling zinc and manganese from the “black mass” (BM) of waste, Zn-MnO₂ batteries, is presented. The leaching process achieves a high efficiency and distribution ratio using the composition of two solvents (Cyanex 272 + diethyl phosphite (DPh)) for Zn(II) extraction. High extraction efficiency with 100% zinc and manganese recovery is also achieved using DESs (cholinum chloride/lactic acid, 1:2, DES 1, and cholinum chloride/malonic acid, 1:1, DES 2). New, greener recycling approaches to metal extraction from the BM of spent Li-ion batteries are presented with ILs ([N_8,8,8,1][Cl], (Aliquat 336), [P_6,6,6,14][Cl], [P_6,6,6,14][SCN] and [Benzet][TCM]) eight DESs, Cyanex 272 and D2EHPA. A high extraction efficiency of Li(I) (41–92 wt%) and Ni(II) (37–52 wt%) using (Cyanex 272 + DPh) is obtained. The recovery of Ni(II) and Cd(II) from the BM of spent Ni-Cd batteries is also demonstrated. The extraction efficiency of DES 1 and DES 2, contrary to ILs ([P_6,6,6,14][Cl] and [P_6,6,6,14][SCN]), is at the level of 30 wt% for Ni(II) and 100 wt% for Cd(II). In this mini-review, the option to use ILs, DESs and Cyanex 272 for the recovery of valuable metals from end-of-life WPCBs is presented. Next-generation recycling technologies, in contrast to the extraction of metals from acidic leachate preceded by thermal pre-treatment or from solid material only after thermal pre-treatment, have been developed with ILs and DESs using the ABS method, as well as Cyanex 272 (only after the thermal pre-treatment of WPCBs), with a process efficiency of 60–100 wt%. In this process, four new ILs are used: didecyldimethylammonium propionate, [N_10,10,1,1][C₂H₅COO], didecylmethylammonium hydrogen sulphate, [N_10,10,1,H][HSO₄], didecyldimethylammonium dihydrogen phosphate, [N_10,10,1,1][H₂PO₄], and tetrabutylphosphonium dihydrogen phosphate, [P_4,4,4,4][H₂PO₄]. The extraction of Cu(II), Ag(I) and other metals such as Al(III), Fe(II) and Zn(II) from solid WPCBs is demonstrated. Various additives are used during the extraction processes. The Analyst 800 atomic absorption spectrometer (FAAS) is used for the determination of metal content in the solid BM. The ICP-OES method is used for metal analysis. The obtained results describe the possible application of ILs and DESs as environmental media for upcycling spent electronic wastes. Full article

(This article belongs to the Section Materials in Separation Science)

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27 pages, 3488 KB

Open AccessEditor’s ChoiceReview

Current Perspectives on the Extraction, Isolation, and Identification of Fats and Fatty Acids Using Conventional and Green Methods

by Ytaiara Lima-Pereira, Esther Maria Oliveira de Souza, David Silva dos Reis, Ian Gardel Carvalho Barcellos-Silva, Karine Sayuri Lima Miki, Valdir F. Veiga-Júnior and Barbara Elisabeth Teixeira-Costa

Separations 2025, 12(6), 160; https://doi.org/10.3390/separations12060160 - 13 Jun 2025

Viewed by 1598

Abstract

The global demand for oils and lipids, particularly those derived from vegetable sources with high polyunsaturated fatty acid content, has posed significant challenges for the food industry. This trend is largely driven by growing consumer awareness of health and nutrition. To meet this [...] Read more.

The global demand for oils and lipids, particularly those derived from vegetable sources with high polyunsaturated fatty acid content, has posed significant challenges for the food industry. This trend is largely driven by growing consumer awareness of health and nutrition. To meet this demand, it is essential to not only identify richer sources of lipids but also develop efficient, sustainable, and environmentally friendly methods for their extraction, isolation, and characterization. In this context, the present work provides a comprehensive review of current perspectives on the extraction, isolation, and identification of lipids and fatty acids, comparing conventional and green methodologies for food applications. Ideally, analytical and processing methodologies for obtaining food-grade materials should prioritize low energy consumption, minimal or no use of hazardous substances, and the generation of non-polluting residues, thereby safeguarding both human health and the environment. In recent years, green extraction techniques have emerged as promising alternatives to conventional methods, offering partial or complete replacements, such as ultrasound-assisted extraction, microwave-assisted extraction, supercritical and subcritical fluid extraction, and others. However, significant advancements are still required to fully address these concerns. Techniques such as chromatography and spectrometry play pivotal roles in the isolation and identification process, especially gas chromatography coupled with mass spectrometry or with flame ionization detectors; while separating individual fatty acids based on their chain length and degree of unsaturation, reversed-phase high-performance liquid chromatography (HPLC) is quite a helpful approach. Furthermore, the isolation and structural elucidation of fatty acids are critical steps in ensuring the nutritional quality and commercial viability of lipid products. Full article

(This article belongs to the Special Issue Extraction and Characterization of Food Components)

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16 pages, 1616 KB

Open AccessEditor’s ChoiceArticle

Comparison of Extraction Techniques for Wide Screening of 230 Pesticides in Water

by Caterina Cacciatori, Jackie Myers, Giulio Mariani, Hung Vu, Bernd Manfred Gawlik and Vincent Pettigrove

Separations 2025, 12(6), 158; https://doi.org/10.3390/separations12060158 - 9 Jun 2025

Cited by 1 | Viewed by 571

Abstract

In this study, weekly grab samples extracted by solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE) were compared for the analysis of 230 pesticides in surface waters. Samples were collected from three different locations around Melbourne, Australia. Analysis was performed using Gas [...] Read more.

In this study, weekly grab samples extracted by solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE) were compared for the analysis of 230 pesticides in surface waters. Samples were collected from three different locations around Melbourne, Australia. Analysis was performed using Gas Chromatography Quadrupole Time of Flight High Resolution Mass Spectrometry (GC-QToF-HRMS). The two extraction techniques were compared, among others, for their limits of detection, recovery, extraction, and quantification efficiency of pesticides, as well as spatial and temporal differences in detected compounds. The target compounds screened were pesticides belonging mainly to the categories of fungicides, insecticides, and herbicides. Although SBSE extracted more pesticides at two out of three sites, SPE extracted total concentrations up to four times higher than SBSE over all sampling sites. The log K_OW of detected pesticides only partially explained the differences in detection, with SBSE performing better in the absorption of hydrophobic compounds. In addition, matrix effects, in particular turbidity, appeared to hinder extraction of contaminants, especially for SBSE. Spatially, SBSE detected 10 pesticides more than SPE at two locations, while the opposite was true at the third location, where turbidity was higher. The types of pesticides detected varied slightly between techniques and locations. The study highlights the complementarity of SBSE and SPE for monitoring pesticides in natural environments. SBSE is an easy-to-use technique and allows for extraction of a higher number of pesticides at trace level, but it might not be the preferred option for highly turbid waters. SPE requires more tedious and complex sample processing but allows for a more accurate quantification of a broader range of pesticides. Full article

(This article belongs to the Special Issue New Techniques for Extraction and Removal of Pesticide Residues)

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13 pages, 1875 KB

Open AccessEditor’s ChoiceArticle

Development and Validation of a Method for the Analysis of Multiple Pesticides in Fishery Products Using Gas Chromatography with Micro-Electron Capture Detection and Gas Chromatography–Tandem Mass Spectrometry

by Myungheon Kim, Mihyun Cho, Changkyo Seo, Jaebin Im, Changhyeon Park, Yoonmi Lee, Mi-Ra Jo, Yong-Sun Moon and Moo-Hyeog Im

Separations 2025, 12(6), 142; https://doi.org/10.3390/separations12060142 - 28 May 2025

Viewed by 513

Abstract

This study aims to develop a simultaneous analytical method for detecting 19 pesticides, including 4,4′-DDD, in fishery products using gas chromatography with micro-electron capture detection (GC-μECD) and gas chromatography–tandem mass spectrometry (GC-MS/MS). A new analytical method was developed to measure pesticide residues in [...] Read more.

This study aims to develop a simultaneous analytical method for detecting 19 pesticides, including 4,4′-DDD, in fishery products using gas chromatography with micro-electron capture detection (GC-μECD) and gas chromatography–tandem mass spectrometry (GC-MS/MS). A new analytical method was developed to measure pesticide residues in fishery products based on the modified Association of Official Analytical Chemists protocol combining quick, easy, cheap, effective, rugged, and safe (QuEChERS) and the Pesticide Analytical Manual for extraction and purification. Extraction was performed using acetonitrile containing 0.1% acetic acid, and purification was conducted with Florisil cartridges. The Florisil cartridges were more effective than QuEChERS in removing impurities and pigments during purification and also resulted in a reduced matrix effect. The validation followed Codex guidelines (CAC/GL 40). The limit of detection ranged from 2 to 3 ng/g, and the limit of quantification (LOQ) from 7 to 10 ng/g. Matrix-matched calibration curves exhibited linearity with coefficients of determination exceeding 0.99 for all target analytes. Accuracy was assessed based on recovery rates, while precision was evaluated using relative standard deviations (RSD) at three spiking levels (LOQ, 10×LOQ, and 50×LOQ). The recovery rates ranged from 62.6 to 119.1%, with RSDs of 0.4 to 19.5%, conforming to Codex guidelines. Full article

(This article belongs to the Special Issue Chemical and Contaminant Residue Analysis via Chromatography)

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14 pages, 815 KB

Open AccessEditor’s ChoiceArticle

Mixed-Mode Chromatography: Studies on Hybrid Retention Mechanisms of Some Antihypertensive Drugs

by Irinel Adriana Badea, Andrei Mihăilă, Dana Elena Popa, Anca Monica Tencaliec and Mihaela Buleandră

Separations 2025, 12(6), 136; https://doi.org/10.3390/separations12060136 - 22 May 2025

Viewed by 426

Abstract

The antihypertensive drugs indapamide, atenolol, metoprolol, propranolol and bisoprolol were considered in this research. Because they have structures that are affected by pH, developing a chromatographic method was challenging. Based on the speciation diagram of these compounds versus pH scale, a mixed-mode stationary [...] Read more.

The antihypertensive drugs indapamide, atenolol, metoprolol, propranolol and bisoprolol were considered in this research. Because they have structures that are affected by pH, developing a chromatographic method was challenging. Based on the speciation diagram of these compounds versus pH scale, a mixed-mode stationary phase (hydrophobic stationary phase, C18 and strong cation exchanger (SCX)) was our first choice. Design of Experiments (DoE) was used to estimate how various factors such as pH, mobile phase composition and flow rate influenced chromatographic performance. As a result, the separation was achieved in 24 min using an aqueous phosphate buffer phase (pH 7.20) and 20 mM triethylamine, with methanol being used as organic modifier (30%). Their retention mechanism was investigated. The new method was validated in term of linearity, limits of detection and quantification, precision, accuracy, and robustness. The method was applied to river water samples, and good results were obtained. Full article

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18 pages, 3393 KB

Open AccessEditor’s ChoiceArticle

Development of a High-Performance Immunoaffinity Separation Technique for Rare Cell Capture

by Dora Szerenyi, Paul Stolk, Jozsef Tovari, Laszlo Takacs and Andras Guttman

Separations 2025, 12(5), 134; https://doi.org/10.3390/separations12050134 - 20 May 2025

Viewed by 621

Abstract

Circulating tumor cell enrichment and enumeration are advancing early detection of cancer, monitoring of therapy response, and even next-generation therapies. Efficiently capturing rare cells from complex biological fluids is essential in both diagnostic and therapeutic applications. EpCAM-positive tumor cells are specifically captured by [...] Read more.

Circulating tumor cell enrichment and enumeration are advancing early detection of cancer, monitoring of therapy response, and even next-generation therapies. Efficiently capturing rare cells from complex biological fluids is essential in both diagnostic and therapeutic applications. EpCAM-positive tumor cells are specifically captured by utilizing covalently immobilized anti-EpCAM monoclonal antibodies onto the surface of chemically modified glass microbeads. To maximize the capture efficiency, bead geometry, immobilization conditions, flow rate, and anticoagulant dosage were systematically optimized. An in vitro flow-capture system was designed and used to evaluate the capture efficiency of the proposed technology by utilizing HTC116 colon cancer cell-spiked model media. The effect of substrate surface pretreatment was characterized by goniometry, while the capture performance was monitored by flow cytometry and fluorescent microscopy. The specific capture ability of the bioactive microbead substrate reached over 130,000 cells in the laboratory-scale cartridge (V(cartridge) = 2.6 cm³; m(bead) = 4 g). This capture efficiency suggests a promising rare-cell capture utilization of the proposed technology and may be used for research, diagnostic, and therapeutic purposes. In this paper, we reported on the development and feasibility test of a high-performance bioactive glass-microbead cell capture substrate. Due to the relevance and novelty of the reported results, with further development, the versatile platform technology presented could be readily implemented to capture tumor cells from complex biological samples and represent an additional complementary tool to existing cancer diagnostics and therapies. Full article

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24 pages, 1664 KB

Open AccessEditor’s ChoiceReview

Microextraction and Eco-Friendly Techniques Applied to Solid Matrices Followed by Chromatographic Analysis

by Attilio Naccarato, Rosangela Elliani and Antonio Tagarelli

Separations 2025, 12(5), 124; https://doi.org/10.3390/separations12050124 - 14 May 2025

Cited by 2 | Viewed by 1196

Abstract

In this review, a 5-year overview on environmentally friendly approaches for the extraction of the most relevant organic pollutants in soil, sediment, particulate matter, and sewage sludge coupled with chromatographic analysis is reported. Organic contaminants encompass various compounds derived from personal care products, [...] Read more.

In this review, a 5-year overview on environmentally friendly approaches for the extraction of the most relevant organic pollutants in soil, sediment, particulate matter, and sewage sludge coupled with chromatographic analysis is reported. Organic contaminants encompass various compounds derived from personal care products, industrial chemicals, microplastics, organic matter combustion, agricultural practices, and plasticizer material. The principles of green analytical chemistry (GAC) and green sample preparation (GSP) serve as a guideline for the development of more environmentally sustainable analytical protocols. This study focuses attention on microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), matrix solid-phase dispersion (MSPD), and microextraction techniques, such as solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE), hollow-fiber liquid-phase microextraction (HF-LPME), spray-assisted droplet formation-based liquid-phase microextraction (SADF-LPME), and dispersive liquid–liquid extraction (DLLME). These approaches represent the most relevant eco-friendly sample preparation for the advanced extraction of target analytes from environmental solid samples. Full article

(This article belongs to the Special Issue Sample Preparation and Chromatographic Analysis of Environmental Samples)

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11 pages, 1447 KB

Open AccessEditor’s ChoiceArticle

Development and Validation of a Sensitive LC-MS/MS Method for the Determination of N-Nitroso-Atenolol in Atenolol-Based Pharmaceuticals

by Soonho Kwon, Sang-Hyun Ahn, Yongha Chang, Joon-Sang Park, Hwangeui Cho and Jung-Bok Kim

Separations 2025, 12(5), 122; https://doi.org/10.3390/separations12050122 - 12 May 2025

Viewed by 1754

Abstract

The recent detection of N-nitroso-atenolol, a mutagenic and potentially carcinogenic impurity in atenolol-based pharmaceuticals, has raised serious safety concerns and emphasized the need for stringent analytical control. This study developed and validated a highly sensitive LC-MS/MS method for quantifying N-nitroso-atenolol in both active [...] Read more.

The recent detection of N-nitroso-atenolol, a mutagenic and potentially carcinogenic impurity in atenolol-based pharmaceuticals, has raised serious safety concerns and emphasized the need for stringent analytical control. This study developed and validated a highly sensitive LC-MS/MS method for quantifying N-nitroso-atenolol in both active pharmaceutical ingredients (APIs) and finished products. Quantification was carried out using multiple reaction monitoring (MRM) under positive-mode electrospray ionization (ESI). Separation was performed on a C18 reversed-phase column with a gradient of water and methanol containing 0.1% formic acid. The method was validated to meet a specification limit of 15 ng/mg, with a linear range of 0.5–80 ng/mL, effectively covering 10–400% of the regulatory threshold. The method exhibited an excellent performance in terms of specificity, accuracy, precision, linearity, and robustness. It achieved a limit of detection (LOD) of 0.2 ng/mL (0.30 ng/mg) and a limit of quantification (LOQ) of 0.5 ng/mL (0.75 ng/mg), alongside a comprehensive uncertainty analysis with an expanded uncertainty of ±3.86 mg/kg. Application to commercial atenolol products confirmed the reliability and practical utility of the method. This validated approach offers a critical tool for pharmaceutical manufacturers and regulatory agencies to monitor and control N-nitroso-atenolol, ensuring compliance and enhancing patient safety. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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17 pages, 2794 KB

Open AccessEditor’s ChoiceArticle

Defluoridation of Water Using Al-Mg-Ca Ternary Metal Oxide-Coated Sand in Adsorption Column Study

by Kiana Modaresahmadi, Amid P. Khodadoust and James Wescott

Separations 2025, 12(5), 119; https://doi.org/10.3390/separations12050119 - 7 May 2025

Viewed by 671

Abstract

Defluoridation of water was investigated in an adsorption column study using Al-Mg-Ca-coated sand (AMCCS), a ternary metal oxide adsorbent with eco-friendly components that were shown to be effective for water defluoridation, in a batch adsorption study. A packed column of the AMCCS sorbent [...] Read more.

Defluoridation of water was investigated in an adsorption column study using Al-Mg-Ca-coated sand (AMCCS), a ternary metal oxide adsorbent with eco-friendly components that were shown to be effective for water defluoridation, in a batch adsorption study. A packed column of the AMCCS sorbent was evaluated as function of column flow rate, solution type, and sorbent recyclability. Adsorption column experiments included two column flow rates of 2 mL/min and 10 mL/min using two different solutions: deionized water and a synthetic solution representative of groundwater. Greater fluoride column adsorption capacity was obtained at the lower flow rate for both solutions, mainly due to longer contact times between solution and AMCCS sorbent. Adsorption of fluoride occurred through physical adsorption, which followed the Langmuir adsorption model and second-order kinetics for deionized water and synthetic solution. A lower AMCCS column fluoride adsorption capacity was observed for the synthetic solution due to the competition from adsorption of other ions in the synthetic solution, whereas fluoride adsorption by the AMCCS column was influenced by interphase mass transfer to a lesser extent using the synthetic solution than deionized water. The re-coating of spent AMCCS sorbent in the adsorption column resulted in effective recycling and reuse of the AMCCS adsorption column for both deionized water and the synthetic solution, rendering the AMCCS adsorption column a recyclable and sustainable flow through water defluoridation system. Full article

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17 pages, 2019 KB

Open AccessEditor’s ChoiceArticle

Free Fatty Acid Determination in Alcoholic and Non-Alcoholic Beers via Liquid Chromatography–High-Resolution Mass Spectrometry Analysis

by Christiana Mantzourani and Maroula G. Kokotou

Separations 2025, 12(5), 114; https://doi.org/10.3390/separations12050114 - 1 May 2025

Viewed by 2668

Abstract

In recent years, non-alcoholic beers have been gaining popularity. Among the various components that affect the flavor and sensory characteristics of beers, free fatty acids (FFAs) are minor components. However, due to their involvement in beer quality, fast and simple methods for analyzing [...] Read more.

In recent years, non-alcoholic beers have been gaining popularity. Among the various components that affect the flavor and sensory characteristics of beers, free fatty acids (FFAs) are minor components. However, due to their involvement in beer quality, fast and simple methods for analyzing FFAs in beers are of importance. In this work, we present a liquid chromatography–high-resolution mass spectrometry (LC-HRMS) method for the rapid determination of FFAs in beers, avoiding a tedious sample preparation and derivatization and allowing the simultaneous study of a large set of FAs, including medium-chain, long-chain, saturated, monounsaturated and polyunsaturated FAs. The method was applied in the analysis of twelve non-alcoholic and nine alcoholic beer samples from the local market, permitting the comparison of their FFA profiling. Among the 37 FAs studied, 29 were quantified, and palmitic, stearic, oleic and myristic acids were identified as the predominant FAs in both alcoholic and non-alcoholic beers. The majority of the predominant long-chain FAs, including palmitic, stearic and myristic acids, were found in decreased amounts in non-alcoholic beers, compared to the alcoholic ones, with the marked exception of oleic acid, which was increased in non-alcoholic beers. Among the medium-chain FAs, octanoic acid was found at lower concentrations in non-alcoholic beers, comparing to regular beers, while lauric acid was slightly increased. Principal component analysis (PCA) suggested the correlation of FFAs with the type of beer (alcoholic or non-alcoholic beer). Full article

(This article belongs to the Special Issue Chromatography/Mass Spectrometry for the Determination of Food Authenticity and Food Analysis)

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17 pages, 3618 KB

Open AccessEditor’s ChoiceArticle

Polymer-Coated Nickel Nanoparticles for CO₂ Capture in Seawater

by Abhishek, Abhishek Ratanpara, Adib Mahmoodi Nasrabadi and Myeongsub Kim

Separations 2025, 12(5), 107; https://doi.org/10.3390/separations12050107 - 24 Apr 2025

Viewed by 1037

Abstract

Carbon capture and storage (CCS) technologies are employed to mitigate global warming by removing carbon from the atmosphere. To enhance carbon capture efficiency, nanoparticles have gained considerable attention as catalysts due to their large surface area, tunable properties, regeneration, and enhanced reactivity. However, [...] Read more.

Carbon capture and storage (CCS) technologies are employed to mitigate global warming by removing carbon from the atmosphere. To enhance carbon capture efficiency, nanoparticles have gained considerable attention as catalysts due to their large surface area, tunable properties, regeneration, and enhanced reactivity. However, it poses some challenges, such as nanoparticle aggregation and reduced effectiveness in sustainable solvents like seawater. To address these limitations and promote an environmentally sustainable method for carbon capture, this study evaluates the CO₂ capture efficiency of seawater using nickel nanoparticles (NiNPs) coated with polyvinylpyrrolidone (PVP) as a catalyst. We examined the time-dependent size variations of CO₂ bubbles in a flow-focusing microchannel using high-speed bubble-based microfluidics, directly associated with transitory CO₂ dissolution into the surrounding solution. We hypothesized that smaller polymer-coated NiNPs, due to their higher surface-to-volume ratio, can enhance CO₂ solubility and capture rates under identical environmental conditions. To verify this, polymer-coated NiNPs of three different sizes—5 nm, 10 nm, and 20 nm—were synthesized and tested. The experiments revealed that 5 nm NiNPs achieved a CO₂ dissolution rate of 77%, in contrast to 71% for 10 nm and 43% for 20 nm particles. These findings validate the hypothesis, demonstrating that smaller nanoparticles facilitate more effective CO₂ capture using equivalent material quantities, thereby potentially improving the overall efficiency of CO₂ reduction. This innovative approach contributes to advancing NiNP-based catalysts for saltwater-based CO₂ capture. Full article

(This article belongs to the Special Issue Application of Advanced Materials and Technologies in the Separation and Adsorption)

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15 pages, 2586 KB

Open AccessEditor’s ChoiceArticle

Enhanced Selective Separation of Pu(IV) and U(VI) Using Novel Diethylene Glycolamide Ligand

by Xiaoyun Guo, Junli Wang, Yao Liu, Haojun Zhao, Hui Wang, Wentao Wang, Baole Li and Taihong Yan

Separations 2025, 12(5), 106; https://doi.org/10.3390/separations12050106 - 23 Apr 2025

Viewed by 507

Abstract

Developing a new efficient separation ligand based on the “CHON” principle to address the limitations of phosphorus containing extractants in nuclear fuel reprocessing can help further simplify the process flow and reduce the amount of secondary waste. Building upon this critical need, a [...] Read more.

Developing a new efficient separation ligand based on the “CHON” principle to address the limitations of phosphorus containing extractants in nuclear fuel reprocessing can help further simplify the process flow and reduce the amount of secondary waste. Building upon this critical need, a novel ligand was developed through a strategic application of the Hard and Soft Acids and Bases (HSAB) theory, integrating a soft donor nitrogen atom into the linear architecture of bis-diglycolamide. This groundbreaking ligand, named N,N′-bis[2-(2-(N,N-dioctylcarbamoyl)ethoxy)ethylacetamido]-N″-diethylenetriamine (TOMDEA-BisDGA), has demonstrated remarkable potential in the extraction of Pu(IV). The study unveils that the ligand demonstrates remarkable selectivity and separation efficiency towards Pu(IV) ions while maintaining an exceptionally low extraction capacity for U(VI) across a wide acidity spectrum of 0.1~6 mol/L. To explain the structure properties of complex formed by the ligand and Pu(IV), a systematic analysis was performed, including slope analysis, proton nuclear magnetic resonance (NMR) titration, and Fourier-transform infrared (FT-IR) spectroscopy. This study explores the coordination and separation behavior of diglycolamide ligands with actinide. This work is expected to provide important information and theoretical bases upon which advanced design and optimization of ligands for high-performance processes for the separation of plutonium might be carried out. Such findings will contribute to the understanding of actinide chemistry and further the design of improved separation methods for nuclear applications. Full article

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23 pages, 527 KB

Open AccessEditor’s ChoiceReview

New Trends in the Methodologies of Determination of Benzodiazepine Residues in Biological Samples

by Israel S. Ibarra, Isaí Vázquez-Garrido, Gabriela Islas and Juan F. Flores-Aguilar

Separations 2025, 12(4), 95; https://doi.org/10.3390/separations12040095 - 11 Apr 2025

Cited by 1 | Viewed by 1380

Abstract

The benzodiazepines are essential drugs used in medicine for anxiolytic, sedative, and hypnotic effects. According to the World Health Organization, the benzodiazepines are the most prescribed hypnotic drugs in the last decade (2010 at time), and their inappropriate use can damage the environment [...] Read more.

The benzodiazepines are essential drugs used in medicine for anxiolytic, sedative, and hypnotic effects. According to the World Health Organization, the benzodiazepines are the most prescribed hypnotic drugs in the last decade (2010 at time), and their inappropriate use can damage the environment and human health. The availability of efficient analytical methods is crucial for the determination of these drugs in a complex matrix such as biological samples in clinical settings. In the last decade, several methods have been developed and have been applied to the detection and determination of benzodiazepines or their derivates. The present manuscript reviews selective and sensitive methodologies based on chromatographic, electrophoretic, and electrochemical systems for the determination of benzodiazepines in biological samples, covering the time of the last years and providing detailed information on sample pretreatment and instrumental conditions. Full article

(This article belongs to the Section Bioanalysis/Clinical Analysis)

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16 pages, 2875 KB

Open AccessEditor’s ChoiceArticle

Extraction and Characterization of TiO₂ Pigments from Commercial Paints for Environmental Studies

by Allan Philippe, Sylvester Ndoli-Kessie, Christian Fricke, Jean-Michel Guigner, Benjamin Heider and Eliana Di Lodovico

Separations 2025, 12(4), 91; https://doi.org/10.3390/separations12040091 - 8 Apr 2025

Cited by 1 | Viewed by 1265

Abstract

TiO₂ nanoparticles are found as pigments in coatings and paints and are, therefore, released into the environment through runoff. To assess their environmental impact, comprehensive fate and ecotoxicity studies necessitate particles closely resembling those released into the environment. In response, we developed [...] Read more.

TiO₂ nanoparticles are found as pigments in coatings and paints and are, therefore, released into the environment through runoff. To assess their environmental impact, comprehensive fate and ecotoxicity studies necessitate particles closely resembling those released into the environment. In response, we developed a method designed to isolate TiO₂ particles from commercial paints. Using six contrasting paints alongside a pure TiO₂ pigment, we evaluated two extraction methods in terms of recovery, purification rate, and preservation of both inorganic and organic particle coatings. The paints and extracts were characterized using cryogenic-TEM, ICP-OES, thermogravimetry, and infrared spectroscopy. In contrast to the alkaline-based extraction method, the extraction with acetic acid facilitated the retention of both inorganic and organic coatings and ensured good removal of organic polymers. Recovery rates exceeded 70% for all paints and extraction methods, yet the complete removal of SiO₂, when present, was not achieved. CaCO₃ removal was effective with both extraction methods. Our developed extraction method enables the isolation of TiO₂-particles similar to those aged within paints. However, we recommend using silicate-free paints when SiO₂ interference is of concern for the study design. Furthermore, this method could be interesting for pigment recycling, offering a gentler alternative to existing techniques which compromise particle coatings. Full article

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23 pages, 11856 KB

Open AccessEditor’s ChoiceReview

Microplastics in the Environment: A Review Linking Pathways to Sustainable Separation Techniques

by Lin Zeng, Long Li, Jueyan Xiao, Penghui Zhou, Xiaoxiang Han, Bohao Shen and Li Dai

Separations 2025, 12(4), 82; https://doi.org/10.3390/separations12040082 - 30 Mar 2025

Cited by 2 | Viewed by 1959

Abstract

Since the mid-20th century, the quantity of microplastics (MPs) has increased significantly, becoming a persistent environmental pollutant widely distributed in global water bodies, soils, and the atmosphere. While plastic materials have brought significant convenience to daily life, the MPs resulting from their degradation [...] Read more.

Since the mid-20th century, the quantity of microplastics (MPs) has increased significantly, becoming a persistent environmental pollutant widely distributed in global water bodies, soils, and the atmosphere. While plastic materials have brought significant convenience to daily life, the MPs resulting from their degradation pose increasing threats to ecosystems and human health. This comprehensive review examines the sources, migration pathways, and ecological impacts of MPs, and critically evaluates the current separation techniques from physical, chemical, and biological perspectives. In particular, numerical simulations of the hydrocyclone separation technique reveal its unique flow characteristics, including turbulent velocity gradients and axial pressure differences, with a separation efficiency of up to 93%. This technique offers advantages such as high efficiency, low energy consumption, and environmental friendliness. In response to the growing microplastic pollution issue, this review emphasizes that the development of future microplastic separation techniques should prioritize separation efficiency, sustainability, and environmental compatibility. Continued research in this field will provide theoretical support for optimizing microplastic pollution control technologies and contribute to achieving environmental protection and sustainable development goals. Full article

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8 pages, 1590 KB

Open AccessEditor’s ChoiceArticle

Separation of D-Amino Acid-Containing Tripeptide L-Asn-D-Trp-L-Phe-NH₂ and Its Diastereomer Using Crown–Ether-Type Chiral Stationary Phase

by Batsaikhan Mijiddorj, Yohei Kayano, Hiroki Yamagishi, Haruto Nakajima and Izuru Kawamura

Separations 2025, 12(3), 67; https://doi.org/10.3390/separations12030067 - 10 Mar 2025

Viewed by 1063

Abstract

Several D-amino acid residue-containing peptides (DAACPs) with antimicrobial, cardio-excitatory, and neuronal activities have been identified in various species. The L-Asn-D-Trp-L-Phe-NH₂ (N(dW)F) tripeptide, derived from Aplysia kurodai, exhibits cardiac activity in invertebrates. The chirality of the tryptophan residue at the second position [...] Read more.

Several D-amino acid residue-containing peptides (DAACPs) with antimicrobial, cardio-excitatory, and neuronal activities have been identified in various species. The L-Asn-D-Trp-L-Phe-NH₂ (N(dW)F) tripeptide, derived from Aplysia kurodai, exhibits cardiac activity in invertebrates. The chirality of the tryptophan residue at the second position in N(dW)F influences its conformation and biological characteristics. We demonstrated the chiral separation of N(dW)F and its diastereomer NWF using (S)-3,3′-diphenyl-1,1′-binaphthyl-20-crown-6-ether columns (CR-I(+)). A reduction in the ratio of acetonitrile and methanol in the mobile phase allowed the complete separation of N(dW)F and its diastereomer, improving the separation factor (α) from 0.96 to 6.28. Molecular dynamics simulations revealed that the interaction of N(dW)F with CR-I(−) was more favorable than with CR-I(+). These findings indicate that the structure of the CR-I column stereoselectively recognizes peptides and facilitates the separation of naturally occurring D-amino acid residue-containing tripeptides. Full article

(This article belongs to the Special Issue Peptide Synthesis, Separation and Purification)

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12 pages, 1419 KB

Open AccessEditor’s ChoiceReview

A Brief Overview of Nanomaterials in Inorganic Selenium Speciation

by Krystyna Pyrzynska

Separations 2025, 12(3), 64; https://doi.org/10.3390/separations12030064 - 9 Mar 2025

Cited by 1 | Viewed by 907

Abstract

Although total selenium content is still useful in many areas, knowledge of its speciation is gaining importance as its various chemical forms have different environmental effects, toxicities and biological utilization. Among several methods used for the isolation and enrichment of selenium species, solid-phase [...] Read more.

Although total selenium content is still useful in many areas, knowledge of its speciation is gaining importance as its various chemical forms have different environmental effects, toxicities and biological utilization. Among several methods used for the isolation and enrichment of selenium species, solid-phase extraction and its alternative approaches are often applied due to their simplicity and high efficiency. This brief overview summarizes the progress made in using different nanostructure sorbents to separate and preconcentrate inorganic selenium species in environmental waters. Nanomaterials are finding increasing applications as they have a large specific surface area and high chemical stability. Functionalizing their surface by covalent or noncovalent interactions with other components, grafting or doping with heteroatoms can improve the separation and removal efficiency. Strategies based on combining selective chemical reactions and separation procedures are discussed. Full article

(This article belongs to the Special Issue Environmental Functional Nanomaterials in Heavy Metal Removal and Pollutant Degradation)

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13 pages, 3079 KB

Open AccessEditor’s ChoiceArticle

The Bio-Desulfurization of Cassiterite–Polymetallic Sulfide Ores Enhanced by a Consortium of Moderately Thermophilic Bacteria

by Mingwei Wang, Weimin Zeng, Zhen Yan, Li Shen, Runlan Yu, Xueling Wu, Jiaokun Li, Guanzhou Qiu, Wolfgang Streit and Yuandong Liu

Separations 2025, 12(3), 61; https://doi.org/10.3390/separations12030061 - 6 Mar 2025

Cited by 1 | Viewed by 722

Abstract

Sulfides should be removed before the recovery of cassiterite from tin-rich minerals due to their similarity in flotation properties. However, the traditional methods used have low selectivity. Therefore, moderately thermophilic microorganisms were used to desulfurize tin ore in this study, and the success [...] Read more.

Sulfides should be removed before the recovery of cassiterite from tin-rich minerals due to their similarity in flotation properties. However, the traditional methods used have low selectivity. Therefore, moderately thermophilic microorganisms were used to desulfurize tin ore in this study, and the success of the microbial community was investigated. The bio-desulfurization rate reached 90% on the 10th day using the mixed culture of Leptospirillum ferriphilum (L. ferriphilum), Sulfobacillus thermosulfidooxidans (S. thermosulfidooxidans), and Acidithiobacillus caldus (A. caldus), while the pure culture needs at least 14 days. The results of X-ray Diffraction (XRD) and Inductively Coupled Plasma show that the sulfides were nearly fully solubilized. XRD results showed no pyrite in the residue, indicating that pyrite was almost fully removed while cassiterite was enriched compared with the original minerals. The high-throughput sequencing analysis showed that S. thermosulfidooxidans were the predominant species during the early bioleaching period, and L. ferriphilum were the predominant species in the following period. A. caldus is consistently detected and accounts for 30–50% of the different growth stages. This study supplied a potentially practical application for the desulfurization in tin ore. Full article

(This article belongs to the Section Purification Technology)

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43 pages, 8193 KB

Open AccessEditor’s ChoiceReview

From Waste to Wealth: A Circular Economy Approach to the Sustainable Recovery of Rare Earth Elements and Battery Metals from Mine Tailings

by Mohammed Omar Sahed Chowdhury and Deniz Talan

Separations 2025, 12(2), 52; https://doi.org/10.3390/separations12020052 - 14 Feb 2025

Cited by 6 | Viewed by 7346

Abstract

The increasing global demand for critical minerals, driven by rapid population growth and the widespread adoption of low-carbon technologies, electric vehicles, and clean energy systems, highlights the urgent need for sustainable resource management. Mine tailings, traditionally considered waste, are now being recognized as [...] Read more.

The increasing global demand for critical minerals, driven by rapid population growth and the widespread adoption of low-carbon technologies, electric vehicles, and clean energy systems, highlights the urgent need for sustainable resource management. Mine tailings, traditionally considered waste, are now being recognized as valuable secondary sources for mineral recovery. This paper compiles a comprehensive review of the four short- and mid-term critical minerals (lithium, cobalt, nickel, and rare earth elements) and provides insights regarding their recovery with a focus on the latest technological advancements. By exploring key innovations in separation processes, the review demonstrates how these technologies are addressing supply chain bottlenecks while simultaneously reducing the environmental footprint of mining operations. The paper also advocates for a holistic approach to mine waste management, integrating mineral recovery with environmental remediation. It emphasizes the dual benefits of recovering valuable resources while purifying contaminated water and mitigating pollution risks. The proposed circular economy model suggests a sustainable blueprint for managing mine tailings, emphasizing resource reuse, waste reduction, and economic viability. Full article

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10 pages, 1639 KB

Open AccessEditor’s ChoiceArticle

Detection of Honey Adulteration by Liquid Chromatography—High-Resolution Mass Spectrometry: Results from an EU Coordinated Action

by Viviana Paiano, Andreas Breidbach, Carolin Lörchner, Tereza Ždiniaková, Olivier De Rudder, Alain Maquet, Lourdes Alvarellos and Franz Ulberth

Separations 2025, 12(2), 47; https://doi.org/10.3390/separations12020047 - 13 Feb 2025

Cited by 2 | Viewed by 4914

Abstract

Honey, a sweet and nutritious food produced by honeybees, is extensively consumed by humans due to its potential health benefits. Unfortunately, the adulteration of honey with inexpensive sugar syrups is a prevalent issue. Verifying the authenticity of honey is crucial for maintaining its [...] Read more.

Honey, a sweet and nutritious food produced by honeybees, is extensively consumed by humans due to its potential health benefits. Unfortunately, the adulteration of honey with inexpensive sugar syrups is a prevalent issue. Verifying the authenticity of honey is crucial for maintaining its quality and safety standards. The aim of this study was to identify the illicit addition of sugar syrups to honey imported into the European Union (EU). The European Commission’s Joint Research Centre (JRC) has employed different analytical approaches to detect several markers of adulteration in honey; however, this paper mainly focuses on the use of Liquid Chromatography–High-Resolution Mass Spectrometry (LC-HRMS). Two qualitative methods were developed to detect mannose (Man), difructose anhydride III (DFA III), 2-acetylfuran-3-glucopyranoside (AFGP), and oligo-/polysaccharides with degrees of polymerization (DPs) of 6 to 11. Out of the 320 honey samples provided by the authorities of the participating EU Member States, 147 (46%) were suspicious for non-compliance with the EU Honey Directive 2001/110/EC, mostly due to the presence of mannose and oligo-/polysaccharides. As a result, the development and standardization of sophisticated and universally recognized testing procedures will increase the capability of official control laboratories to detect honey adulteration and will serve as a powerful preventive measure against fraudulent practices in the global honey market. Full article

(This article belongs to the Special Issue Chromatography/Mass Spectrometry for the Determination of Food Authenticity and Food Analysis)

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14 pages, 2617 KB

Open AccessEditor’s ChoiceArticle

Headspace Determination of Acetone and Aromatic Hydrocarbons in Soil Using a Homebuilt, Inexpensive Gas Chromatograph with Photoionization Detection

by Cameron Shane, Carly M. Kennell, Michael J. Geyer, Thomas N. Loegel and Neil D. Danielson

Separations 2025, 12(2), 46; https://doi.org/10.3390/separations12020046 - 12 Feb 2025

Viewed by 1109

Abstract

We have designed, built, and characterized an inexpensive gas chromatograph with photoionization detection using readily commercially available components. These include a home carbonation CO₂ cylinder for the carrier gas, headspace sampling using a low pressure six port valve, a standard 30 m [...] Read more.

We have designed, built, and characterized an inexpensive gas chromatograph with photoionization detection using readily commercially available components. These include a home carbonation CO₂ cylinder for the carrier gas, headspace sampling using a low pressure six port valve, a standard 30 m wide-bore capillary column, a consumer convection oven including added insulation with a thermocouple, and a photoionization sensor enclosed in a flow cell. The chromatography retention time reproducibility is good due to temperature control within 0.5 °C. The headspace linearity response using a 0.5 mL injection of benzene was from 10 to 250 ppm, with the limit of detection estimated at 4 ppm. The application of this instrument to the headspace monitoring of four soil samples spiked with a commercial adhesive cleaner containing acetone, ethyl benzene, and xylenes was possible. The interaction of acetone with the two different potting soil samples, likely due to their high organic content, was persistent for at least 30 min, even above an ambient temperature (60 °C). A comparison of linear plots of the signal versus volatilization time over the first 20 min showed substantially larger slopes for the two yard soil samples, indicating the rapid volatilization of acetone from these lower organic content soils, as compared to the two potting soil samples. This GC-PID instrument can be considered portable because it can be easily taken apart, transported, and reassembled. One viable option for the extension of the applications of this instrument is to provide hands-on teaching of GC. Full article

(This article belongs to the Section Chromatographic Separations)

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15 pages, 6707 KB

Open AccessEditor’s ChoiceArticle

Chiral Separation and Determination of Enantiomer Elution Order of Novel Ketamine Derivatives Using CE-UV and HPLC-UV-ORD

by Elisabeth Seibert, Eva-Maria Hubner and Martin G. Schmid

Separations 2025, 12(2), 44; https://doi.org/10.3390/separations12020044 - 11 Feb 2025

Viewed by 2116

Abstract

Besides the well-known hallucinogenic ketamine, various novel ketamine derivatives are available on the illicit drug market, sold as designer drugs. Minor chemical changes to the parent compound aim to circumvent existing narcotic drug laws while mimicking the effects of the original substance. Ketamine [...] Read more.

Besides the well-known hallucinogenic ketamine, various novel ketamine derivatives are available on the illicit drug market, sold as designer drugs. Minor chemical changes to the parent compound aim to circumvent existing narcotic drug laws while mimicking the effects of the original substance. Ketamine and some of its derivatives possess a chiral centre and therefore exist as two enantiomers. While differences in the effects of S- and R-ketamine are well studied, this is not the case for ketamine derivatives. Therefore, the development and adaptation of suitable enantioseparation methods for those compounds is important to face the problems of the constantly changing drug market. In this study, different chiral separation methods for capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) were tested on 11 ketamine derivatives. Some of them were enantioseparated for the first time due to their novelty. All compounds were at least partially separated on both instruments. HPLC separations were conducted using four different polysaccharide-based chiral stationary phases. Furthermore, an optical rotation detector coupled to the HPLC enabled the determination of the enantiomer elution order. In CE analysis, enantioseparation was achieved using 2% (w/v) acetyl-β-cyclodextrin or carboxymethyl- β-cyclodextrin in 10 mM di-sodium hydrogen phosphate as the background electrolyte in capillary electrophoresis. Full article

(This article belongs to the Section Chromatographic Separations)

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13 pages, 873 KB

Open AccessEditor’s ChoiceArticle

HILIC-DAD Method for Simultaneous Determination of Acid and Basic Drugs: Application to the Quantitation of Ibuprofen, Atenolol, and Salbutamol in Urine After Solid-Phase Extraction

by Noelia Rosales-Conrado, Laura Pedrera-Cajas, Elvira Soliño-Rodríguez and María Eugenia León-González

Separations 2025, 12(2), 26; https://doi.org/10.3390/separations12020026 - 26 Jan 2025

Cited by 1 | Viewed by 1354

Abstract

A simple method has been developed for the simultaneous analysis of ibuprofen (acid drug), and salbutamol and atenolol (basic drugs) in urine samples at concentrations of 0.40 µg·mL⁻¹. Simultaneous chromatographic separation has been possible using hydrophilic interaction liquid chromatography (Kinetex HILIC [...] Read more.

A simple method has been developed for the simultaneous analysis of ibuprofen (acid drug), and salbutamol and atenolol (basic drugs) in urine samples at concentrations of 0.40 µg·mL⁻¹. Simultaneous chromatographic separation has been possible using hydrophilic interaction liquid chromatography (Kinetex HILIC^® column (2.1 mm × 150 mm, 2.6 μm particle size diameter and 100 Å pore size) combined with gradient elution by employing a mixture of acetonitrile–acetate buffer 5 mM at pH 6 (from 95:5 to 75:25 (v/v)) as the mobile phase. Detection was performed at 227 and 275 nm. The simultaneous preconcentration and cleaning of the sample has been possible by solid-phase extraction using the HLB ExtraBond^® polymeric-type sorbent (which is a pyrrolidone-modified divinylbenzene polystyrene type). It has provided recoveries between (63 ± 9)% for salbutamol, (74 ± 8)% for ibuprofen, and (96 ± 9)% for atenolol in 10 mL of synthetic urine containing 4.0 μg of each of the drugs analyzed. The detection limits were 0.025 µg·mL⁻¹ for ibuprofen, µg·mL⁻¹ for salbutamol, and 0.007 µg·mL⁻¹ for atenolol. The detection limits obtained allow the evaluation of the free forms of ibuprofen, atenolol, and salbutamol at the excreted concentration levels at the therapeutic doses usually administered. The coefficients of variation between days were in the range 4.5–10.9%. Full article

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20 pages, 3734 KB

Open AccessEditor’s ChoiceArticle

Strengthened Effect of Surface-Active Ionic Liquids on Curcumin Solubility and Extraction Performance of Curcuminoids

by Dan Li, Yuxin Qin, Jingxing Li, Subhan Mahmood, Jianqin Shi, Yu Cao and Shun Yao

Separations 2025, 12(2), 29; https://doi.org/10.3390/separations12020029 - 26 Jan 2025

Viewed by 988

Abstract

As a kind of bioactive component in the rhizome of natural plant Curcuma longa L. (turmeric), curcumin is almost insoluble in water at neutral and acidic pH, which limits its further utilization and development. At the same time, traditional extraction and separation processes [...] Read more.

As a kind of bioactive component in the rhizome of natural plant Curcuma longa L. (turmeric), curcumin is almost insoluble in water at neutral and acidic pH, which limits its further utilization and development. At the same time, traditional extraction and separation processes typically require the use of a large number of organic solvents. Ionic liquids (ILs) are organic molten salts with melting points below 100 °C. When an ionic liquid exists in a liquid state at or near room temperature, it is referred to as a room-temperature ionic liquid (RTIL). They have a temperature range, good physical and chemical stability, and good structural designability. They have a strong solubilization enhancement effect for many organic compounds. This study first explored the molecular forms of curcumin in ionic liquid aqueous solutions and the intermolecular interactions between curcumin and ionic liquids using spectral analysis and computational chemistry methods; furthermore, using an ionic liquid aqueous solution as an extraction agent, curcumin-like substances (curcuminoids) were extracted from turmeric powders under ultrasound assisted conditions, revealing the relationship between the structure of the ionic liquid and the extraction efficiency. After that, a kinetic study was conducted for the extraction of curcuminoids from turmeric powders, using second-order kinetics fitting to obtain the rate constant and initial extraction rate during the extraction process. Finally, the comparison with a ComplexGAPI tool and antioxidant experiment was performed on the extraction by using ionic liquids and traditional solvent. The full results can provide reference for the design of IL extractants and their application for natural products. Full article

(This article belongs to the Special Issue Green Separation and Purification Technology)

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17 pages, 2312 KB

Open AccessEditor’s ChoiceArticle

Green Chemistry Method for Analyzing Bisphenol A in Milk

by Angela M. Encerrado Manriquez and Wen-Yee Lee

Separations 2025, 12(2), 25; https://doi.org/10.3390/separations12020025 - 25 Jan 2025

Viewed by 2231

Abstract

A simple, fast, green, and sensitive method for determining Bisphenol A (BPA) levels in commercial milk was developed using a solventless sample preparation technique known as stir bar sorptive extraction, coupled with thermal desorption–gas chromatography/mass spectrometry. BPA was selected due to its ubiquitous [...] Read more.

A simple, fast, green, and sensitive method for determining Bisphenol A (BPA) levels in commercial milk was developed using a solventless sample preparation technique known as stir bar sorptive extraction, coupled with thermal desorption–gas chromatography/mass spectrometry. BPA was selected due to its ubiquitous presence in the environment and its classification as an endocrine-disrupting chemical of concern (i.e., its ability to mimic hormone functions). Studies have reported that BPA can leach into various food sources, including milk, a dietary staple for infants. It is critical to have an effective and efficient process for monitoring the presence of BPA in milk to protect children’s health. Current detection methods for BPA in milk are lengthy and tedious and tend to require the use of organic solvents for the extraction of BPA. This optimized “green” method provides an effective alternative for BPA detection in a challenging matrix, e.g., milk. Factors such as pH (1.5, 6, and 13), temperature (70–80 °C), and sonication (1 h, 2 h, and 3 h) were studied with a BPA-spiked whole milk sample (final concentration of 8 ppb) to optimize the extraction efficiency without the use of solvents. The developed methodology improves BPA recovery from whole milk by over 50%, with a detection limit in the parts per trillion range (45 ng/L). The sample preparation developed in this report rendered a more sensitive option for analyzing BPA in milk, with a limit of detection in the parts per trillion range (compared to low ppb) even though the recovery performance is not as good as in reported studies (54% vs. >85%); nonetheless, it provides a green alternative for future studies assessing BPA exposure through dairy products. Full article

(This article belongs to the Special Issue Chromatographic Methods for Environment, Biota and Food Contaminants Analysis)

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21 pages, 531 KB

Open AccessEditor’s ChoiceReview

Plant Sample Preparation for Metabolomics, Lipidomics, Ionomics, Fluxomics, and Peptidomics

by Walace Breno da Silva, Gabriel Felipe Hispagnol, Emanuel Victor dos Santos Nunes, Ian Castro-Gamboa and Alan Cesar Pilon

Separations 2025, 12(2), 21; https://doi.org/10.3390/separations12020021 - 24 Jan 2025

Cited by 3 | Viewed by 3471

Abstract

Plant metabolomics, lipidomics, ionomics, fluxomics, and peptidomics are essential approaches for exploring how plants respond to epigenetic, pathological, and environmental stimuli through comprehensive chemical profiling. Over the past decades, significant progress has been made in protocols and methodologies to address the challenges in [...] Read more.

Plant metabolomics, lipidomics, ionomics, fluxomics, and peptidomics are essential approaches for exploring how plants respond to epigenetic, pathological, and environmental stimuli through comprehensive chemical profiling. Over the past decades, significant progress has been made in protocols and methodologies to address the challenges in sample collection and extraction. Despite these advancements, sample preparation remains intricate, with ongoing debates about the most effective strategies. This review emphasizes the importance of clear research questions and well-designed experiments to minimize complexity, save time, and enhance reproducibility. It provides an overview of the key steps in these fields, including harvesting, drying, extraction, and data pre-acquisition for major analytical platforms. By discussing best practices and common challenges, this review aims to streamline methods and promote more consistent and reliable research outcomes. Full article

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14 pages, 1399 KB

Open AccessEditor’s ChoiceArticle

Development of a Validated HPLC-UV Method for the Determination of Panthenol, Hesperidin, Rutin, and Allantoin in Pharmaceutical Gel-Permeability Study

by Sofia Almpani, Pavlina-Ioanna Agiannitou, Paraskevi Kyriaki Monou, Georgios Kamaris and Catherine K. Markopoulou

Separations 2025, 12(2), 19; https://doi.org/10.3390/separations12020019 - 22 Jan 2025

Cited by 2 | Viewed by 2137

Abstract

A pressure ulcer is the necrosis of the skin and tissues due to prolonged pressure. Its prevention and treatment are of great importance not only for the health but also for the patient’s quality of life and are considered the highest priority. In [...] Read more.

A pressure ulcer is the necrosis of the skin and tissues due to prolonged pressure. Its prevention and treatment are of great importance not only for the health but also for the patient’s quality of life and are considered the highest priority. In the present study, a reliable analytical method is developed for the quantitative determination of panthenol, hesperidin, rutin, and allantoin by HPLC and UV detectors. The substances were formulated into a pharmaceutical gel, with healing and regenerative properties recommended for first- and second-degree bedsores. Their separation was achieved with a ZIC-Hilic column (150 × 4.6 mm), 5 μm, and a gradient elution system (Solvent A: CH₃CN-H₂O, 90:10 v/v/v and Solvent B: CH₃CN-H₂O, 10:90 v/v). The method was evaluated based on the required specifications (%RSD < 2, % Recovery > 96.7%) and was applied for the quantitative extraction of the active substances in the gel. The purification of the samples was carried out using experimental design and Cross-D-Optimal methodology (%RSD < 2.2, % Recovery > 96.9%). Subsequently, the gel was studied in terms of the transdermal permeation of the active pharmaceutical ingredients (APIs) through vertical Franz cells and their behavior (P_app values) was compared with a similar aqueous suspension product (reference formulation). The samples were reconstituted by lyophilization and extraction with methanol. According to the results, the drugs exhibit satisfactory penetration, ensuring the healing of problems that may occur in the skin and dermis. Full article

(This article belongs to the Collection State of the Art in Separation Science)

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15 pages, 732 KB

Open AccessEditor’s ChoiceArticle

Assessment of Green Extraction Techniques in the Utilization of Oak Tree (Quercus robur) and Mugwort (Artemisia vulgaris) Biomass for the Production of Bioactive Extracts

by David Villanueva-Bermejo, Diego Martín Hernández, Elvis Judith Hernández, Susana Santoyo and Tiziana Fornari

Separations 2025, 12(1), 17; https://doi.org/10.3390/separations12010017 - 18 Jan 2025

Viewed by 1229

Abstract

The aim of this study was to investigate the suitability of Pressurized Liquid Extraction (PLE) and Supercritical Fluid Extraction (SFE) for Quercus robur bark and Artemisia vulgaris extraction. PLE of Q. robur and A. vulgaris were carried out at different temperatures with water, [...] Read more.

The aim of this study was to investigate the suitability of Pressurized Liquid Extraction (PLE) and Supercritical Fluid Extraction (SFE) for Quercus robur bark and Artemisia vulgaris extraction. PLE of Q. robur and A. vulgaris were carried out at different temperatures with water, ethanol and several hydroalcoholic mixtures. SFE of A. vulgaris was performed at different pressures and ethanol concentrations. The anti-inflammatory activity of Q. robur extracts, the antibacterial activity of A. vulgaris extracts and the antioxidant activity of the extracts from both materials were determined. The highest phenolic compound content and antioxidant activity of Q. robur extracts were achieved with water at 100 °C (487.97 mg GAE/g and 3741 µg trolox/g). The highest values for A. vulgaris extracts were obtained with ethanol at 200 °C (149.16 mg/g and 437.13 µmol/g). The ethanolic extract at 150 °C from A. vulgaris had a noticeable anti-inflammatory activity (inhibition of TNF-α and IL-6 secretion near basal values and inhibition of IL-1β higher than 80% at 20 µg/mL). A. vulgaris extracts obtained by SFE exerted antibacterial activity against E. coli (IC₅₀ of 1388 µg/mL with neat SCCO₂ at 15 MPa) and S. aureus (1406 µg/mL using SCCO₂ with 10% ethanol). Full article

(This article belongs to the Special Issue Research Progress for Isolation of Plant Active Compounds)

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22 pages, 3209 KB

Open AccessEditor’s ChoiceReview

Microextraction-Based Techniques for the Determination of Beta-Blockers in Biological Fluids: A Review

by Styliani Nisyriou and Constantinos K. Zacharis

Separations 2025, 12(1), 14; https://doi.org/10.3390/separations12010014 - 12 Jan 2025

Cited by 4 | Viewed by 1521

Abstract

Sample preparation is a critical step in the analytical process. Apart from the traditional sample cleanup approaches, microextraction-based techniques have attracted much attention in recent years and especially from researchers working in the analysis of beta-blockers. Developing sensitive and selective analytical methods is [...] Read more.

Sample preparation is a critical step in the analytical process. Apart from the traditional sample cleanup approaches, microextraction-based techniques have attracted much attention in recent years and especially from researchers working in the analysis of beta-blockers. Developing sensitive and selective analytical methods is essential for detecting these compounds in complex matrices. The present review aims to provide an overview of microextraction-based analytical techniques for the determination of beta-blockers in biological samples, covering a time frame of the last decade. Detailed information on materials/coatings and instrumental configurations are provided. Full article

(This article belongs to the Section Bioanalysis/Clinical Analysis)

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30 pages, 2179 KB

Open AccessEditor’s ChoiceReview

Advancements in Microextraction by Packed Sorbent: Insights into Sorbent Phases and Automation Strategies

by Rafael Oliveira Martins, João Victor Basolli Borsatto, Camila Will and Fernando Mauro Lanças

Separations 2025, 12(1), 11; https://doi.org/10.3390/separations12010011 - 8 Jan 2025

Cited by 3 | Viewed by 1702

Abstract

Miniaturized solid-based approaches have added an eco-friendly dimension to analytical procedures, establishing themselves as promising strategies for a wide range of applications. Among these, microextraction by packed sorbent (MEPS) stands out due to its ability to facilitate efficient sample interaction with a densely [...] Read more.

Miniaturized solid-based approaches have added an eco-friendly dimension to analytical procedures, establishing themselves as promising strategies for a wide range of applications. Among these, microextraction by packed sorbent (MEPS) stands out due to its ability to facilitate efficient sample interaction with a densely packed sorb ent phase within the microextraction system. MEPS offers several advantages, including preconcentration capabilities and the use of minimal sample and solvent volumes, making it an appealing choice for modern analytical workflows. Since the extraction efficiency is largely dictated by the sorbent phase, recent advancements in sorbent design have garnered considerable attention in the field of sample preparation. Innovations in sorbent phases have not only enhanced the MEPS efficiency but also enabled the development of semi- and fully automated systems, paving the way for high-throughput methodologies. These advancements have elevated MEPS beyond traditional offline miniaturized sample preparation methods, offering new opportunities for streamlined and scalable analyses. Therefore, this study provides a comprehensive overview of novel sorbent phases used in MEPS, with a particular focus on both bio-based and synthetic materials. Furthermore, it explores the semi- and fully automated aspects of MEPS, highlighting current trends, technological advancements, and future directions in this rapidly evolving field. Full article

(This article belongs to the Special Issue Separation Techniques on a Miniaturized Scale)

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