Separations, Volume 9, Issue 4 (April 2022) – 20 articles

The aim of the present study was to develop a rapid, simple and reliable method for the identification and quantification of six mycotoxins in wine using liquid chromatography with electrospray ionization tandem mass spectrometry. The analytical method was fully validated, and calibration curves were made with correlation coefficients >0.9970. A short analysis time and acceptable extraction efficiency were achieved by a direct extraction method of analytes (ochratoxin A, aflatoxin B1, B2, G1, G2 and Zearalenone) with acetonitrile. LOD values were from 0.03 to 0.27 μg kg⁻¹, and LOQ values were from 0.08 to 0.81 μg kg⁻¹, with recoveries at various values from 77 to 108%. The expanded uncertainty was 5–21% expressed at a coverage level of k = 2, at a confidence level of approximately 95%. The performance criteria of the method were fully met according to European legislation (EC) 401/2006. The method was successfully applied to wine samples from Cyprus. The method was simple, low cost, quick, accurate, and sensitive. Full article

The purpose of this study was to evaluate the key quality characteristics of olive oil with a main focus on the biophenolic content, its beneficial effects on health and the contribution of various quality characteristics to its health claims, as well as its influence from various parameters. Samples from different traditional oil-producing regions of Greece were initially examined for the most important quality parameters, such as the percentage of free acidity, the number of peroxides and the spectrophotometric investigation in the ultraviolet. The samples were then tested for their biophenolic content, expressed in milligrams of tyrosol, and its derivatives per 20 g of olive oil using the analytical technique high-performance liquid chromatography (HPLC). Then, the biophenol contents of the analyzed samples were compared based on the presented intensities in terms of the variety and the area of cultivation, the altitude, the type of cultivation, the extraction system in the mill and the time interval from olive harvest to oiling. Finally, according to the results, the content of biophenols in olive oil and its health claims were found to be influenced by the various parameters with which they were compared. Full article

The utilization of phosphoric acid in various sectors, e.g., food industry, is controlled by the authorized concentration limit of impurities. However, industrial phosphoric acid is contaminated with undesirable impurities (such as F, Al, Fe, Mg, etc.). Herein, this study aimed to evaluate the efficiency of the membrane purification process of pretreated industrial phosphoric acid using a premodified nanofiltration membrane. We demonstrated that the prior pretreatment steps for industrial phosphoric acid allowed the elimination of sulfate, fluorine and arsenic. Further purification of the obtained pretreated phosphoric acid using membrane cells reduced the concentrations of Cd, Al, Fe and rare earth elements by 94.81, 99.30, 99.63 and 96.67%, respectively. The membrane is functionalized by a deposit of a high molecular weight polycationic polymer of polyethyleneimines in order to produce a highly charged membrane surface to enhance the separation efficiency, selectivity and stability of the membrane. We found that the purification process relies on electrostatic repulsion between the functionalized membrane and highly charged ions, and the reduction rate of metals is a cation charge-dependent parameter. The laboratory and industrial pilot scale results showed that this process allows the production of food-grade phosphoric acid. Full article

Among all the emerging contaminants, fragrances are gaining more relevance for their proven allergenic and, in some cases, endocrine-disrupting properties. To date, little information exists on their concentration in the air. This study aims to fill this gap by developing a method for the determination of semivolatile fragrances in the indoor gaseous phase with sampling protocols usually adopted for the collection of atmospheric particulate matter (sampling time 24 h, flow rate 10 L min⁻¹) and instrumental analysis by gas chromatography coupled with mass spectrometry. The method was developed on 66 analytes and tested at three concentration levels: 20 compounds showed analytical recoveries ≥72% with percentage standard deviations always better than 20%. For most compounds, negligible sampling breakthroughs were observed. The method was then applied to real samples collected in a coffee bar and in a private house. Considering the fragrances for which the method has shown good effectiveness, the highest concentrations were observed for carvone in the coffee bar (349 ng m⁻³) and camphor in the house (157 ng m⁻³). As concerns certain or suspected endocrine disruptors, lilyal and galaxolide were detected at both sites, α-isomethylionone was the second most concentrated compound in the house (63.2 ng m⁻³), musk xylene and musk ketone were present at lower concentration (≈ 1 or 2 ng m⁻³). Full article

This study aimed to develop a simple, high-throughput method based on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) followed by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) for the rapid determination of multi-class pesticide residues in raw milk. With acidified acetonitrile as the extraction solvent, the raw milk samples were pretreated with the modified QuEChERS method, including extraction, salting-out, freezing, and clean-up processes. The target pesticides were acquired in a positive ion electrospray ionization mode and an All ions MS/MS mode. The developed method was validated, and good performing characteristics were achieved. The screening detection limits (SDL) and limits of quantitation (LOQ) for all the pesticides ranged within 0.1–20 and 0.1–50 μg/kg, respectively. The recoveries of all analytes ranged from 70.0% to 120.0% at three spiked levels (1 × LOQ, 2 × LOQ, and 10 × LOQ), with relative standard deviations less than 20.0%. The coefficient of determination was greater than 0.99 within the calibration linearity range for the detected 195 pesticides. The method proved the simple, rapid, high throughput screening and quantitative analysis of pesticide residues in raw milk. Full article

From the viewpoint of resource and energy-saving, the high extraction rate of alternating liquid–liquid flow (slug flow) is important given that it enables its novel use in extraction. Additionally, a specific extraction rate must be maintained for the practical application of slug flow to chemical extraction. Although slug flow is easily generated, controlling the slug length is difficult. In this study, two diaphragm pumps were interlocked to generate a slug flow. By linking the movement of the diaphragms of the two pumps, we could successfully and efficiently control the slug length, and the interlocking diaphragms could easily control the length of the aqueous and oil phase segments of the slug flow. The lengths of the aqueous and oil phases of the slug flow, which could not be quantitatively controlled, could be expressed in terms of the linear velocity of the liquid, the kinematic viscosity, and the tube diameter using the Reynolds number. This relation aids the extraction equipment design using slug flow. Furthermore, the mass transfer coefficient of extraction obtained using the slug flow generated by the developed device was similar to that obtained by the conventional method of a syringe pump. These results indicate that slug flow can be successfully applied to extraction processes. Full article

Oxy-fuel combustion technology is an effective way to reduce CO₂ emissions. An ionic liquid [emim][Tf₂N] was used to capture the CO₂ in flue gas from oxy-fuel combustion plant. The process of the CO₂ capture was simulated using Aspen Plus. The results show that when the liquid–gas ratio is 1.55, the volume fraction of CO₂ in the exhaust gas is controlled to about 2%. When the desorption pressure is 0.01 MPa, desorption efficiency is 98.2%. Additionally, based on the designability of ionic liquids, a hypothesis on the physical properties of ionic liquids is proposed to evaluate their influence on the absorption process and heat exchanger design. The process evaluation results show that an ionic liquid having a large density, a large thermal conductivity, and a high heat capacity at constant pressure is advantageous. This paper shows that from capture energy consumption and lean circulation, oxy-fuel combustion is a more economical method. Furthermore, it provides a feasible path for the treatment of CO₂ in the waste gas of oxy-fuel combustion. Meanwhile, Aspen simulation helps speed up the application of ionic liquids and oxy-fuel combustion. Process evaluation helps in equipment design and selection. Full article

Curcuma longa (turmeric) has traditionally been used in Ayurvedic, Unani and herbal drugs to cure numerous ailments. Due to the high demand, the quantitative standardization of herbal products is challenging to maintain their quality. We aim to develop a rapid, sensitive and validated high-performance thin-layer chromatography (HPTLC) method for the simultaneous determination and quantification of curcumin I, curcumin II and curcumin III in C. longa and herbal formulation. The three standards were separated using centrifugal preparative thin-layer chromatography (CPTLC) silica gel and identified by different spectroscopic methods. The developed HPTLC method was validated by following ICH guidelines (linearity; limit of detection, LOD; limit of quantitation; accuracy; precision; and robustness). The calibration curves of both the compounds were linear (50–500 ng/spot), with a correlation coefficient (r²) of >999. The developed HPTLC method was effectively applied to the concurrent detection and quantification of curcumins I–III in fresh, dry rhizomes and the herbal formulation of C. longa extracts was obtained by hot and cold extraction methods. Full article

For the first time, the high-performance liquid chromatography–diode array detector (HPLC–DAD) approach was operated for the simultaneous assessment of methyl nicotinate (MN), methyl salicylate (MS), ethyl salicylate (ES) and 2-hydroxyethyl salicylate (HES) in one pharmaceutical formulation. The limits of detection of MN, HES, MS and ES were found to be 0.0144, 0.0455, 0.0087 and 0.0061 μg/mL. The recovery percentages and relative standard deviations ranged from 93.48 to 102.12% and 0.301 to 6.341% for all active ingredients. Accordingly, the previously described data demonstrate the sensitivity, accuracy and precision of the developed method. Therefore, the investigated approach was effectively applied for the simultaneous assessment of MN, HES, MS and ES in DEEP HEAT Spray. Full article

Catalytic membranes, as a combination of heterogeneous advanced oxidation and membrane technology reaction systems, have important application prospects in the treatment of dyes and other organics. In practical applications, it is still challenging to construct catalytic membranes with excellent removal efficiency and fouling mitigation. Herein, molybdenum disulfide-iron oxyhydroxide (MoS₂-FeOOH) was fabricated using iron oxide and MoS₂ nanoflakes, which were synthesized by the hydrothermal method. Furthermore, by changing the concentration of MoS₂-FeOOH, the MoS₂-FeOOH/polyethersulfone (PES) composite ultrafiltration membrane was obtained with improved hydrophilicity, permeability, and antifouling capacity. The pure water flux of the composite membrane reached 385.3 L/(m²·h), which was 1.7 times that of the blank PES membrane. Compared with the blank membrane, with the increase of MoS₂-FeOOH content, the MoS₂-FeOOH/PES composite membranes had better adsorption capacity and catalytic performance, and the membrane with 3.0% MoS₂-FeOOH content (M4) could be achieved at a 60.2% methylene blue (MB) degradation rate. In addition, the membrane flux recovery ratio (FRR) of the composite membrane also increased from 25.6% of blank PES membrane (M0) to more than 70% after two cycles of bovine serum albumin (BSA) filtration and hydraulic cleaning. The membrane with 2.25% MoS₂-FeOOH content (M3) had the best antifouling performance, with the largest FRR and the smallest irreversible ratio (R_ir). Catalytic self-cleaning of the composite membrane M3 recovered 95% of the initial flux with 0.1 mol/L H₂O₂ cleaning. The MoS₂-FeOOH/PES composite membranes with the functions of excellent rejection and antifouling capacity have a good prospect in the treatment of printing and dyeing wastewater composed of soluble dyes. Full article

Cottonseed hull is a livestock feed with large daily consumption. If pesticide residues exceed the standard, it is easy for them to be introduced into the human body through the food chain, with potential harm to consumer health. A method for multi-residue analysis of 237 pesticides and their metabolites in cottonseed hull was developed by gas-chromatography and liquid-chromatography time-of-flight mass spectrometry (GC-QTOF/MS and LC-QTOF/MS). After being hydrated, a sample was extracted with 1% acetic acid in acetonitrile, then purified in a clean-up tube containing 400 mg MgSO₄, 100 mg PSA, and 100 mg C18. The results showed that this method has a significant effect in removing co-extracts from the oily matrix. The screening detection limit (SDL) was in the range of 0.2–20 μg/kg, and the limit of quantification (LOQ) was in the range of 0.2–20 μg/kg. The recovery was verified at the spiked levels of 1-, 2-, and 10-times LOQ (n = 6), and the 237 pesticides were successfully verified. The percentages of pesticides with recovery in the range of 70–120% were 91.6%, 92.8%, and 94.5%, respectively, and the relative standard deviations (RSDs) of all pesticides were less than 20%. This method was successfully applied to the detection of real samples. Finally, this study effectively reduced the matrix effect of cottonseed hull, which provided necessary data support for the analysis of pesticide residues in oil crops. Full article

The chemical profile of the Cannabis sativa L. female inflorescences is rather complex being characterized by a large number of molecules belonging to different chemical classes. Considering the numerous applications in various fields, including the medical and pharmaceutical sectors, that have seen a large use of Cannabis genus in recent years, a precise characterization of the matrices is essential. In this regard, the application of adequate and suitable sampling and analysis techniques becomes important in order to provide an identification of the metabolites characterizing the profile of the sample under examination. The goal of this work is to provide additional information on the chemical composition of the inflorescences of five C. sativa different cultivars grown in Emilia Romagna (Italy) through the application of sophisticated analysis techniques such as Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry and Ultra-Performance Liquid Chromatography-Mass Spectrometry (SPME-GC-MS and UPLC-MS). The obtained data highlighted the presence of a high number of volatile and non-volatile compounds, thus allowing a comparative evaluation of the different samples. Furthermore, an in-depth statistical survey by Principal Components Analysis (PCA) and HeatMap, Hierarchical luster Analysis (HCA) and Partial Least Squares Discriminant Analysis (PLS-DA-VIP), was conducted to consider any correlations between the investigated cultivars. The findings of this study may help to provide more information on the C. sativa inflorescences useful for potential applications of their metabolites in scientific research. Full article

There are probably no biological samples that did more to spur interest in proteomics than serum and plasma. The belief was that comparing the proteomes of these samples obtained from healthy and disease-affected individuals would lead to biomarkers that could be used to diagnose conditions such as cancer. While the continuing development of mass spectrometers with greater sensitivity and resolution has been invaluable, the invention of strategic strategies to separate circulatory proteins has been just as critical. Novel and creative separation techniques were required because serum and plasma probably have the greatest dynamic range of protein concentration of any biological sample. The concentrations of circulating proteins can range over twelve orders of magnitude, making it a challenge to identify low-abundance proteins where the bulk of the useful biomarkers are believed to exist. The major goals of this article are to (i) provide an historical perspective on the rapid development of serum and plasma proteomics; (ii) describe various separation techniques that have made obtaining an in-depth view of the proteome of these biological samples possible; and (iii) describe applications where serum and plasma proteomics have been employed to discover potential biomarkers for pathological conditions. Full article

The double vortex-finder hydrocyclone formed by a coaxial insertion of an internal vortex-finder with a smaller diameter inside the conventional single vortex-finder used to obtain two kinds of products from the internal and external overflows in one classification has attracted wide attention. To further improve the classification performance of the hydrocyclone, the effects of the internal vortex-finder diameter and length on the classification performance were studied by numerical simulation and response surface modeling with the behavior of fluid and particle motion in the double vortex-finder hydrocyclone as the research object. The results showed that the split ratio and pressure drop of internal and external overflow increased with the diameter of the internal vortex-finder. The classification performance was optimal when the diameter ratio of internal and external overflow was 0.88, the yield of −20 μm particles was more than 80.0%, and the highest was 95.0%. Increasing the internal vortex-finder length could reduce the coarse particle content and improve the classification accuracy of the internal overflow product. When the length of the internal vortex-finder is larger than 80 mm, the +30 μm yield was lower than 20.0%, and the maximum k value was 16.3%; the k is the significant factor used to characterize the effectiveness of −20 μm particle collection. The response surface modeling revealed that the internal vortex-finder diameter was the most important factor affecting the distribution rate of internal overflow. This paper is expected to advance the development of the classification industry. Full article

Flavanols are a class of polyphenols that have become the focus of much research because of their medicinal properties. For this paper, a new method to determine polyphenols in nutraceutical samples was developed, based on solid-liquid extraction and further analysis by liquid chromatography. Analytes were recovered by ultrasound-assisted extraction, using a mixture of methanol/water/hydrochloric acid (70:29:1, v:v:v) as the solvent. Reversed-phase high-performance liquid chromatography with ultraviolet/visible (HPLC-UV/Vis) and fluorescence detection (HPLC-FLD) were developed to determine the content of the principal flavanols. The HPLC-FLD method showed better selectivity and sensitivity, so it was selected for further studies. The analytical parameters established with FLD were satisfactory in terms of linearity (R² ≥ 0.993), repeatability (RSD% ≥ 2.2), and limits of detection of 0.1 mg L⁻¹ or below. The nutraceutical samples were analyzed by HPLC-FLD to determine the compositional profiles of flavanols, then they were subsequently treated using chemometric methods, such as principal component analysis (PCA). Results showed that the study of compositional profiles from the selected flavanols was sufficient for description and discrimination purposes. The cranberry samples were the richest in flavanols, procyanidin A2 being the principal flavanol, and artichoke samples the least rich. Full article

Background: Malignant melanoma is the most serious type of skin cancer with the highest mortality rate. Extracellular vesicles (EVs) have potential as new tumor markers that could be used as diagnostic and prognostic markers for early detection of melanoma. Methods: EVs were purified from the blood serum of melanoma patients using two methods—ultracentrifugation and PEG precipitation—and analyzed by mass spectrometry and immunoblot. Results: We identified a total of 585 unique proteins; 334 proteins were detected in PEG-precipitated samples and 515 in UC-purified EVs. EVs purified from patients varied in their size and concentration in different individuals. EVs obtained from stage II and III patients were, on average, smaller and more abundant than others. Detailed analysis of three potential biomarkers—SERPINA3, LGALS3BP, and gelsolin—revealed that the expression of SERPINA3 and LGALS3BP was higher in melanoma patients than healthy controls, while gelsolin exhibited higher expression in healthy controls. Conclusion: We suggest that all three proteins might have potential to be used as biomarkers, but a number of issues, such as purification of EVs, standardization, and validation of methods suitable for everyday clinical settings, still need to be addressed. Full article

With an increasing appreciation for the unique pharmacological properties associated with distinct, individual cannabinoids of Cannabis sativa, there is demand for accurate and reliable quantification for a growing number of them. Although recent methods are based on highly selective chromatography-mass spectrometry technology, most are limited to a few cannabinoids, while relying on unnecessarily sophisticated and expensive ultra-high performance liquid chromatography and tandem mass spectrometry. Here we report an optimised, simple extraction method followed by a reliable and simple high performance liquid chromatography method for separation. The detection is performed using a time-of-flight mass spectrometer that is available in most natural products research laboratories. Due to the simplicity of instrumentation, and the robustness resulting from a high resolution in the chromatography of isobaric cannabinoids, the method is well suited for routine phytocannabinoid analysis for a range of applications. The method was validated in terms of detection and quantification limits, repeatability, and recoveries for a total of 17 cannabinoids: detection limits were in the range 11–520 pg when using a 1 µL sample injection volume, and the recovery percentages ranged from 85% to 108%. The validated method was subsequently applied to determine cannabinoid composition in the inflorescences of several medicinal Cannabis sativa varieties. Full article

Menbutone is often used to stimulate the hepato-digestive activity in case of digestive disorders and hepatic insufficiency in different species (cattle, sheep, goats, pigs, horses, dogs) because it has choleretic and cholagogue effects and increases gastric and pancreatic juices. The objective was to develop and validate an HPLC method to quantify menbutone in sheep plasma using sparfloxacin as internal standard. The HPLC mobile phase consisted of acetonitrile:monopotassium phosphate solution. The method was validated according to EMA guideline (EMEA/CHMP/EWP/192217/2009). Mean retention times of menbutone and sparfloxacin were 4.5 and 2.2 min, respectively. The method met all specifications of the EMA guideline, being selective and linear in the range of 0.2–100 µg/mL (R² ≥ 0.99). The within-run precision range was 0.19–8.21%, with an accuracy of 102.99–119.52% for the lower limit of quantitation (LLOQ). For the other values (LOW, MED, HIGH) the precision range was 0.01–4.77%, with an accuracy of 85.17–109.67%. The LLOQ was 0.2 µg/mL, and no interference from the biological matrix was found. Stability of menbutone in the biological matrix at different storage conditions was also demonstrated. Thus, the method can be used to determine menbutone concentrations in plasma sheep in different types of studies. Full article

The quantitative determination of levamisole (LMS), mebendazole (MBZ), and the two metabolites of MBZ, 5-hydroxymebendazole (HMBZ) and 2-amino-5-benzoylbenzimidazole (AMBZ), in poultry eggs (hen, duck, and goose) was achieved with high-performance liquid chromatography–tandem triple quadrupole mass spectrometry (HPLC–MS/MS). Samples were pretreated by liquid–liquid extraction and solid-phase extraction (LLE–SPE) to extract the target compounds, and an Oasis MCX SPE column was used for purification. Determination was performed on an Xbridge C18 column with 0.1% formic acid aqueous solution and acetonitrile as mobile phases. LMS, MBZ, HMBZ, and AMBZ were detected in a triple-quadrupole mass spectrometer with ESI in positive mode and quantified with an external standard. In blank eggs, the target analyte concentrations were within the limits of quantification (LOQs)—25 μg/kg (LMS) and 150 μg/kg (MBZ, HMBZ, and AMBZ)—and the matrix-matched calibration curves had good linearity (R² ≥ 0.9990). In the same concentration range, the average recoveries of the target analytes were 85.98–97.38% (n = 6); the relative standard deviation (RSD), intraday RSD, and interday RSD ranged from 2.06 to 4.22%, 1.40 to 5.85%, and 2.34 to 6.32%, respectively. The limits of detection (LODs) ranged from 0.03 to 0.33 µg/kg, and the LOQs ranged from 0.08 to 1.00 µg/kg. Experimental verification showed that the HPLC–MS/MS method exhibited high specificity and sensitivity for quantitative analyses of egg samples. This study provides a rapid, efficient, and sensitive method for the simultaneous detection of LMS, MBZ, HMBZ, and AMBZ residues in foods of animal origin. Full article