Search Results (14)

A magnetic deep eutectic solvent-based single-drop microextraction technique coupled with high-performance liquid chromatography (MDES-SDME-HPLC) was established for the determination of five triazine herbicides in environmental water samples. MDES, used as the extraction solvent, was composed of heptanoic acid, methyltrioctylammonium chloride, and iron chloride. This pretreatment method requires only 50 μL of MDES, thereby avoiding the use of large volumes of toxic organic solvents. The MDES containing the target triazine herbicides was rapidly separated from the aqueous matrix by applying an external magnetic force, thus eliminating the need for centrifugation or additional reagents to achieve phase separation. The method demonstrated a linear range of 0.2–20 μg L⁻¹, with a limit of detection of 0.06 μg L⁻¹. Recoveries obtained from different environmental water matrices ranged from 75.5% to 102.4%. The greenness of the method was confirmed using five independent green analytical assessment tools. This approach represents a green and efficient analytical technique for detecting triazine herbicides in environmental water samples. Full article

The extensive use of nitro compounds in agriculture, industry, armaments, and pharmaceuticals, along with their toxic effects on living organisms, necessitates efficient and environmentally sustainable analytical methods. Traditional extraction techniques often involve practices that are not eco-friendly, such as the use of large volumes of solvents, toxic chemicals, and the generation of significant waste; therefore, the single-drop microextraction technique was involved in overcoming these limitations. This study shows an environmentally friendly method for nitro compound analysis focusing on NB (Nitrobenzene), 2-NT (2-Nitrotoluene), 3-NT (3-Nitrotoluene), 4-NT (4-Nitrotoluene), 1,3-DNB (1,3-Dinitrobenzene), 1,2-DNB (1,2-Dinitrobenzene), 2,4-DNT (2,4-Dinitrotoluene), and TNT (Trinitrotoluene). To separate and to detect selected nitro compounds, gas chromatography with an electron capture detector was utilized, which is highly selective for analytes containing nitro groups. To determine optimal experimental conditions, extraction parameters were studied, including the impact of salt addition, temperature, and pH on extraction efficiency. Key performance parameters, such as limit of detection (LOD), limit of quantification (LOQ), repeatability, extraction recoveries, calibration range, and matrix effects, were assessed. The LOD values ranged from 0.01 to 0.09 μg/L in deionized water, 0.01 to 0.06 μg/L in tap water, 0.01 to 0.03 μg/L in seawater, and 0.03 to 0.11 μg/L in model forensic rinse water. The optimized method was successfully applied to the determination of nitro compounds in real environmental water samples and forensic rinse water samples. The environmental sustainability and greenness of the proposed method was evaluated with the AGREE, AGREEprep, and AESA techniques. Full article

Beryllium (Be) is one of the most toxic non-radioactive elements on the periodic table, and its presence or intake can negatively impact both the environment and human health. Classified as a carcinogen, Be is dangerous even at trace concentrations, stressing the necessity of developing reliable methods for quantifying it at very low levels. Spectrometric techniques for quantifying Be vary in sensitivity and applicability, with inductively coupled plasma mass spectrometry (ICP-MS) being the most sensitive for ultra-trace analysis. Flame atomic absorption spectrometry (FAAS) is suitable for higher Be concentrations, but preconcentration techniques can significantly lower detection limits. Electrothermal atomic absorption spectrometry (ETAAS) provides enhanced sensitivity for low-level Be quantification, further optimized using pyrolytically coated graphite tubes and chemical modifiers such as Mg(NO₃)₂ or Pd(NO₃)₂. Effective separation and preconcentration techniques are essential for reliable Be quantification in complex matrices. Liquid-liquid extraction (LLE), including single-drop microextraction (SDME) and dispersive liquid-liquid microextraction (DLLME), have evolved to reduce the use of hazardous solvents. When combined with ETAAS, surfactant-assisted DLLME using agents like cetylpyridinium ammonium bromide (CPAB) and dioctyl sodium sulfosuccinate (AOT) achieves preconcentration factors of approximately 25, reducing LOD to 1 ng/L. Vesicle-mediated DLLME coupled with ETAAS further enhances sensitivity, allowing detection limits as low as 0.01 ng/L in seawater. Cloud-point extraction (CPE), often employing Triton X-114, facilitates Be extraction using complexing agents or nanomaterials like graphene oxide. These advancements are critical for accurately quantifying Be at ultra-trace levels in diverse environmental and biological samples, overcoming challenges posed by low analyte concentrations and matrix interferences. Full article

Essential oils are vital constituents of oil-bearing plants. However, their screening still demands harvesting of the plant for laboratory analysis. We report herein a simple, rapid and robust headspace bubble-in-drop microextraction screening technique (BID-SPME) requiring only small amounts of plant material. The optimised method uses 0.5 g of the crushed plant leaves sample obtained in a 2 mL capped chromatography vial, heated to 55 °C and sampled with 2 µL heptadecane in a Hamilton gastight syringe equilibrated for 15 min exposed to the headspace volume. The method was applied to three plants, Pinus radiata, Tagetes minuta and Artemisia afra, which are known for their essential oil content. The method was able to extract at least 80% of the oil constituents in such abundance that they could be easily annotated using the gas chromatography–mass spectrometry (GC–MS) mass spectral libraries. The major volatile organic compounds (VOCs) detected included tagetone, terpinen-4-ol, ocimenone, caryophyllene, dihydrotagetone, terpinolene and artemisia ketone, just to mention a few, at different concentrations in different plants. Importantly, these annotated VOCs were also reported in other studies in the same and even different plants, extracted using normal steam distillation and importantly those reported in the literature for different extraction techniques. Full article

Liquid phase-based microextraction techniques (LPµETs) have attracted great attention from the scientific community since their invention and implementation mainly due to their high efficiency, low solvent and sample amount, enhanced selectivity and precision, and good reproducibility for a wide range of analytes. This review explores the different possibilities and applications of LPμETs including dispersive liquid–liquid microextraction (DLLME) and single-drop microextraction (SDME), highlighting its two main approaches, direct immersion-SDME and headspace-SDME, hollow-fiber liquid-phase microextraction (HF-LPME) in its two- and three-phase device modes using the donor–acceptor interactions, and electro membrane extraction (EME). Currently, these LPμETs are used in very different areas of interest, from the environment to food and beverages, pharmaceutical, clinical, and forensic analysis. Several important potential applications of each technique will be reported, highlighting its advantages and drawbacks. Moreover, the use of alternative and efficient “green” extraction solvents including nanostructured supramolecular solvents (SUPRASs, deep eutectic solvents (DES), and ionic liquids (ILs)) will be discussed. Full article

Two cheap, simple and reproducible methods for the electrophoretic determination of homocysteine thiolactone (HTL) in human urine have been developed and validated. The first method utilizes off-line single drop microextraction (SDME), whereas the second one uses off-line SDME in combination with field amplified sample injection (FASI). The off-line SDME protocol consists of the following steps: urine dilution with 0.2 mol/L, pH 8.2 phosphate buffer (1:2, v/v), chloroform addition, drop formation and extraction of HTL. The pre-concentration of HTL inside a separation capillary was performed by FASI. For sample separation, the 0.1 mol/L pH 4.75 phosphate buffer served as the background electrolyte, and HTL was detected at 240 nm. A standard fused-silica capillary (effective length 55.5 cm, 75 μm id) and a separation voltage of 21 kV (~99 μA) were used. Electrophoretic separation was completed within 7 min, whereas the LOD and LOQ for HTL were 0.04 and 0.1 μmol/L urine, respectively. The calibration curve in urine was linear in the range of 0.1–0.5 μmol/L, with R² = 0.9991. The relative standard deviation of the points of the calibration curve varied from 2.4% to 14.9%. The intra- and inter-day precision and recovery were 6.4–10.2% (average 6.0% and 6.7%) and 94.9–102.7% (average 99.7% and 99.5%), respectively. The analytical procedure was successfully applied to the analysis of spiked urine samples obtained from apparently healthy volunteers. Full article

In the last decades, a myriad of materials has been synthesized and utilized for the development of sample preparation procedures. The use of their magnetic analogues has gained significant attention and many procedures have been developed using magnetic materials. In this context, the benefits of a new class of magnetic ionic liquids (MILs), as non-conventional solvents, have been reaped in sample preparation procedures. MILs combine the advantageous properties of ionic liquids along with the magnetic properties, creating an unsurpassed combination. Owing to their unique nature and inherent benefits, the number of published reports on sample preparation with MILs is increasing. This fact, along with the many different types of extraction procedures that are developed, suggests that this is a promising field of research. Advances in the field are achieved both by developing new MILs with better properties (showing either stronger response to external magnetic fields or tunable extractive properties) and by developing and/or combining methods, resulting in advanced ones. In this advancing field of research, a good understanding of the existing literature is needed. This review aims to provide a literature update on the current trends of MILs in different modes of sample preparation, along with the current limitations and the prospects of the field. The use of MILs in dispersive liquid–liquid microextraction, single drop microextraction, matrix solid-phase dispersion, etc., is discussed herein among others. Full article

Bile salts are naturally occurring chiral surfactants that are able to solubilize hydrophobic compounds. Because of this ability, bile salts were exploited as chiral selectors added to the background solution (BGS) in the chiral micellar electrokinetic chromatography (MEKC) of various small molecules. In this review, we aimed to examine the developments in research on chiral MEKC using bile salts as chiral selectors over the past 20 years. The review begins with a discussion of the aggregation of bile salts in chiral recognition and separation, followed by the use of single bile salts and bile salts with other chiral selectors (i.e., cyclodextrins, proteins and single-stranded DNA aptamers). Advanced techniques such as partial-filling MEKC, stacking and single-drop microextraction were considered. Potential applications to real samples, including enantiomeric impurity analysis, were also discussed. Full article

In this review, the ever-increasing use of deep eutectic solvents (DES) in microextraction techniques will be discussed, focusing on the reasons needed to replace conventional extraction techniques with greener approaches that follow the principles of green analytical chemistry. The properties of DES will be discussed, pinpointing their exceptional performance and analytical parameters, justifying their current extensive scientific interest. Finally, a variety of applications for commonly used microextraction techniques will be reported. Full article

The fully automated system of single drop microextraction coupled with capillary electrophoresis (SDME-CE) was developed for in-line preconcentration and determination of muscimol (MUS) and psilocin (PSC) from urine samples. Those two analytes are characteristic active metabolites of Amanita and Psilocybe mushrooms, evoking visual and auditory hallucinations. Study analytes were selectively extracted from the donor phase (urine samples, pH 4) into the organic phase (a drop of octanol layer), and re-extracted to the acidic acceptor (background electrolyte, BGE), consisting of 25 mM phosphate buffer (pH 3). The optimized conditions for the extraction procedure of a 200 µL urine sample allowed us to obtain more than a 170-fold enrichment effect. The calibration curves were linear in the range of 0.05–50 mg L⁻¹, with the correlation coefficients from 0.9911 to 0.9992. The limit of detections was determined by spiking blank urine samples with appropriate standards, i.e., 0.004 mg L⁻¹ for PSC and 0.016 mg L⁻¹ for MUS, respectively. The limits of quantification varied from 0.014 mg L⁻¹ for PSC and 0.045 mg L⁻¹ for MUS. The developed method practically eliminated the sample clean-up step, which was limited only to simple dilution (1:1, v/v) and pH adjustment. Full article

The current clinical and forensic toxicological analysis of body fluids requires a modern approach to sample preparation characterized by high selectivity and enrichment capability, suitability for micro-samples, simplicity and speed, and the possibility of automation and miniaturization, as well as the use of small amounts of reagents, especially toxic solvents. Most of the abovementioned features may be realized using so-called microextraction techniques which cover liquid-phase techniques (e.g., single-drop microextraction, SDME; dispersive liquid–liquid microextraction, DLLME; hollow-fiber liquid-phase microextraction, HF-LPME) and solid-phase extraction techniques (solid-phase microextraction, SPME; microextraction in packed syringes, MEPS; disposable pipette tip extraction, DPX; stir bar sorption extraction, SBSE). Some other extraction methodologies like dispersive solid-phase extraction (d-SPE) or magnetic solid-phase extraction (MSPE) can also be easily miniaturized. This review briefly describes and characterizes the abovementioned extraction methods, and then presents their current applications to the preparation of body fluids analyzed for bioactive compounds in combination with appropriate analytical methods, mainly chromatographic and related techniques. The perspectives of the analytical area we are interested in are also indicated. Full article

Single-drop microextraction (SDME) was coupled with surface-enhanced Raman scattering (SERS) to provide sample extraction and pre-concentration for detection of analyte at low concentrations. A gold nanohole array substrate (AuNHAS), fabricated by interference lithography, was used as SERS substrate and para-mercaptobenzoic acid (p-MBA) was tested as a probe molecule, in the concentration range 10⁻⁸–10⁻⁴ mol L⁻¹. With this approach, a limit of 10⁻⁷ mol L⁻¹ was clearly detected. To improve the detection to lower p-MBA concentration, as 10⁻⁸ mol L⁻¹, the SDME technique was applied. The p-MBA Raman signature was detected in two performed extractions and its new concentration was determined to be ~4.6 × 10⁻⁵ mol L⁻¹. This work showed that coupling SDME with SERS allowed a rapid (5 min) and efficient pre-concentration (from 10⁻⁸ mol L⁻¹ to 10⁻⁵ mol L⁻¹), detection, and quantification of the analyte of interest, proving to be an interesting analytical tool for SERS applications. Full article

Green sample preparation is one of the most challenging aspects in green analytical chemistry. In this framework, miniaturized microextraction techniques have been developed and are widely performed due to their numerous positive features such as simplicity, limited need for organic solvents, instrumentation of low cost and short time of extraction. Also, ionic liquids (ILs) have unequivocally a “green” character, which they owe to their unique properties including the re-usage, the high reaction efficiency and selectivity in room temperature, the ability to dissolve both organic and inorganic compounds, and thermal stability. In the present review, the recent advances in the application of ionic liquids in miniaturized liquid and solid phase extraction techniques as extractants, intermediate solvents, mediators and desorption solvents are discussed, quoting the advantages and drawbacks of each individual technique. Some of the most important sample preparation techniques covered include solid-phase microextraction (SPME), dispersive liquid-liquid microextraction (DLLME), single-drop microextraction (SDME), stir bar sorptive extraction (SBSE), and stir cake sorptive extraction (SCSE). Full article

Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several innovative liquid-phase microextraction (LPME) techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME). Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact. Full article