Green Sample Preparation Technique Research Articles

Liquid-phase microextraction approach using supramolecular solvent formed in aqueous systems based on di(2-ethylhexyl)phosphoric acid salt: Spectrophotometric determination of antipyrine in saliva

In this study, di(2-ethylhexyl)phosphoric acid salt was investigated as a double-chain anionic surfactant for supramolecular solvent formation in a liquid-phase microextraction procedure for the first time. Inorganic electrolytes (sodium salts) were shown to be coacervation agents, due to their salting-out property in solution of sodium di(2-ethylhexyl)phosphate, obtained by deprotonation of the acid. The physico-chemical properties of the newly synthesised solvents were studied. Sodium carbonate and sodium phosphate were found to be the most suitable coacervation agents, due to their alkaline nature and low viscosity of the supramolecular solvent phases they produce. The extraction ability of the novel solvent was demonstrated in liquid-phase microextraction of a colored derivative of antipyrine from saliva for further spectrophotometric determination. The extraction recovery was found to be 70 %. The proposed green sample preparation technique enabled the exclusion of traditional toxic solvents and reduction of reagent consumption. The satisfactory analytical performance of the procedure was validated with real sample analysis. The calibration graph was linear over the concentration range of 0.03 to 0.5 mmol/L. The limit of detection (3σ) and limit of quantification (10σ), calculated from blank tests, were 0.01 and 0.03 mmol/L, respectively.

Controlled construction of 2D hierarchical core-shell ZnO/MnO2 nanosheets on Nitinol fiber with enhanced adsorption performance for selective solid-phase microextraction of trace polycyclic aromatic hydrocarbons in water samples

BackgroundPolycyclic aromatic hydrocarbons (PAHs) are an important class of potentially toxic persistent organic pollutants in environmental water. Their concentrations are usually too low to allow for direct determination with analytical instruments, and the preconcentration is required prior to instrumental analysis. Solid phase microextraction (SPME) is considered as a high-performance green sample preparation technique for volatile and non-volatile organic compounds due to its high enrichment factor. In fact, the nature of SPME coatings governs the adsorption performance. Therefore, more efforts have devoted to the controlled construction of novel long-life SPME fibers with enhanced adsorption performance and improved adsorption selectivity. Results2D hierarchical core-shell ZnO/MnO2 nanosheets (NSs) were constructed on a Nitinol (NiTi) fiber substrate by layer-by-layer assembly for enhanced and selective SPME of PAHs. Firstly, hexagonal ZnO NSs were electrodeposited on the NiTi substrate. Subsequently smaller secondary MnO2 NSs were uniformly grown on the surface of ZnO NSs by a facile hydrothermal oxidation process. ZnO NSs were well protected by the chemically stable MnO2 shell, making the coating highly durable and efficient for SPME application. Meanwhile, the ZnO/MnO2 NSs coating demonstrated superior adsorption performance for PAHs. After the optimization of SPME conditions, the proposed SPME-HPLC-UV method exhibited good analytical performance for preconcentrating and determining trace PAHs with wide linear ranges (0.03–200 μg L−1) and low LODs (0.005–0.112 μg L−1) as well as good repeatability (1.4%-6.9%) and fiber-to-fiber reproducibility (5.3%-7.1%). Moreover, the proposed method showed good precision and recovery in the preconcentration and determination of target PAHs in real water samples. SignificanceAs compared with representative commercially available fibers, the NiTi@ZnO/MnO2 NSs fiber showed enhanced adsorption efficiency and improved adsorption selectivity for PAHs. The constructed fiber can be used as an alternative to commercial fibers for the adsorption and preconcentration of target PAHs in the environmental water samples. Moreover, the preparation strategy is expected to provide new insights into the precisely controlled construction of the efficient and stable core-shell bimetallic oxide nanostructures on the superielastic NiTi-based fibers.

Applying novel economic simple green sample preparation procedures on natural and industrial specimens for chromatographic determination of insecticidal residues

Spraying a tertiary blend of the insecticides (hexythiazox, imidacloprid, and thiamethoxam), on tomato fruits, is a routine in agriculture-attentive countries. A simple green sample preparation technique was developed and applied to the field samples. Specific HP-TLC and RP-HPLC methodologies are established to estimate the residual insecticides and applied to the prepared field specimens. In the planner chromatographic methodology, methanol:chloroform:glacial acetic acid:triethyl amine (8.5:1.5:0.2:0.1, v/v) is recommended as a mobile system. The other one is columnar chromatography; acetonitrile: water (20:80, v/v), pH 2.8, is recommended as a mobile system. The validation parameters were examined following the ICH rules. The means percentages and standard deviations of the accuracy of the HP-TLC method for the determined compounds were 99.66 ± 0.974, 99.41 ± 0.950, and 99.89 ± 0.983, correspondingly. The values were 99.24 ± 0.921, 99.69 ± 0.681, and 99.20 ± 0.692, correspondingly, when they were determined by the RP-HPLC method. The relative standard deviation percentages of the methods’ repeatability and intermediate precision ranged from 0.389 to 0.920. Both methods were highly specific having resolution factors of ≥ 1.78 and selectivity factors of ≥ 1.71. They were applied to the field samples perfectly.

Magnet Integrated Fabric Phase Sorptive Extraction for the Extraction of Resin Monomers from Human Urine Prior to HPLC Analysis

In this work, a method for the simultaneous determination of four resin monomers: Bisphenol A, bisphenol A methacrylate glycidate, triethyleneglycol-dimethacrylate, and urethane dimethacrylate, from human urine using magnet integrated fabric phase sorptive extraction (MI-FPSE), followed by high performance liquid chromatography (HPLC) diode array detection (HPLC-DAD), is presented. MI-FPSE is a novel configuration of FPSE that incorporates the stirring and extraction mechanism into one device, resulting in an improved extraction kinetic factor. FPSE is a green sample preparation technique that uses a flexible surface, such as cellulose, coated with a polymeric material using sol–gel technology. Poly(tetrahydrofuran) (PTHF) material was selected, due to its higher efficiency in terms of recovery rate among the studied MI-FPSE membranes. Optimization of the extraction process was performed based on several extraction and elution parameters. The method was validated for its linearity, selectivity, accuracy, precision, and stability of the samples. For the four compounds, the LOD and LOQ were 0.170 ng/μL and 0.050 ng/μL, respectively. The relative standard deviation of the method was less than 9.8% and 11.9%, for the within-day and between-day precision, respectively. The relative recoveries were between 85.6 and 105.2% in all cases, showing a good accuracy. The effectiveness of the proposed method was confirmed through successful application to the bioanalysis of real urine samples.

Metal-Phase Microextraction (MPME) as a Novel Solvent-Free and Green Sample Preparation Technique: Determination of Cadmium in Infant Formula and Real Water Samples

Metal-Phase Microextraction (MPME) as a Novel Solvent-Free and Green Sample Preparation Technique: Determination of Cadmium in Infant Formula and Real Water Samples

Fabric Phase Sorptive Extraction for the Determination of Anthracyclines in Sewage

Anthracyclines are a group of antineoplastic compounds used to treat acute leukemia and other cancers, and they are excreted after consumption by patients. These chemicals are often found in sewage at very low concentration levels. For this reason, the development of sensitive analytical methodologies capable of determining them at low concentrations is of prime importance. A simple, fast and sensitive analytical method using fabric phase sorptive extraction (FPSE) followed by ultra-high performance liquid chromatography with fluorescence detection (UHPLC-FD) has been developed and validated for the extraction of anthracyclines from sewage samples. FPSE is a green, cheap, simple, selective and rapid sample preparation technique. The different parameters that affect the performance of the FPSE process, including extraction time, eluting solvent, elution time and pH, were optimized. The developed method showed satisfactory reproducibility, with intraday and interday RSD values lower than 15% for all the compounds and limits of detection between 0.1–0.15 µg·L−1. The unique combination of sample preparation by this micro-extraction technique with fluorescence detector have resulted in the satisfactory extraction of highly polar anthracyclines, without any noticeable matrix effect, a very common shortcoming of exhaustive sample preparation technique such as solid phase extraction (SPE) and mass spectrometry.

A fabric phase sorptive extraction method for the LC-UV determination of bisphenol A and leaching monomers from dental materials in human saliva

A rapid and simple fabric phase sorptive extraction (FPSE) procedure is developed for the simultaneous extraction of four monomers (Bisphenol A, BPA; Triethylene glycol dimethacrylate, TEGDMA; Urethane dimethacrylate, UDMA; Bisphenol A-glycidyl methacrylate, BisGMA) in human saliva, prior to the determination by high pressure liquid chromatography with an ultraviolet-visible detector. FPSE is a green sample preparation technique, harmonized with the principles of Green Analytical Chemistry (GAC), which utilizes a flexible surface, such as cellulose, chemically coated with a polymeric material using sol-gel technology. FPSE membranes are characterized by superior chemical stability and any solvent or solvent mixture can be used for elution. Among twelve different sol-gel coated membranes, an FPSE membrane coated with sol-gel polytetrahydrofuran (sol-gel PTHF) was found optimum to extract four target compounds from saliva samples, which were first centrifuged. Parameters with most significant impact on the extraction efficiency of FPSE including elution solvent, utilization of magnetic stirring, extraction time have been comprehensively studied and optimized. The studied compounds’ separation was carried out by a Perfect Sil 120 ODS-2 chromatographic column (250 mm × 4.0 mm, 5 μm), using a mobile phase constituting of acetonitrile-water 70:30 % v/v (isocratic elution). The total analysis time was 10 min. Detection was achieved by an ultraviolet-visible detector at 220 nm. The method was validated in terms of sensitivity, linearity, trueness, precision, selectivity and stability of samples. For all four compounds, the limit of detection and the limit of quantification were 0.075 ng/μL and 0.25 ng/μL, respectively. Relative recovery rates were between 90.0 and 106.7%, while RSD values were <8.1 and 12% for interday and intraday repeatability, respectively. Youden & Steiner approach was applied to study method’s ruggedness and reusability of the media was tested, which enhanced the green nature of technique.

Application of a Low Transition Temperature Mixture for the Dispersive Liquid-Liquid Microextraction of Illicit Drugs from Urine Samples.

The use of psychoactive substances is a serious problem in today’s society and reliable methods of analysis are necessary to confirm their occurrence in biological matrices. In this work, a green sample preparation technique prior to HPLC-MS analysis was successfully applied to the extraction of 14 illicit drugs from urine samples. The isolation procedure was a dispersive liquid–liquid microextraction based on the use of a low transition temperature mixture (LTTM), composed of choline chloride and sesamol in a molar ratio 1:3 as the extracting solvent. This mixture was classified as LTTM after a thorough investigation carried out by FTIR and DSC, which recorded a glass transition temperature at −71 °C. The extraction procedure was optimized and validated according to the main Food and Drug Administration (FDA) guidelines for bioanalytical methods, obtaining good figures of merit for all parameters: the estimated lower limit of quantitation (LLOQ) values were between 0.01 µg L−1 (bk-MMBDB) and 0.37 µg L−1 (PMA); recoveries, evaluated at very low spike levels (in the ng-µg L−1 range), spanned from 55% (MBDB) to 100% (bk-MMBDB and MDPV); finally, both within-run and between-run precisions were lower than 20% (LLOQ) and 15% (10xLLOQ).

Flexible and hierarchical metal-organic framework composite as solid-phase media for facile affinity-tip fabrication to selectively enrich glycopeptides and phosphopeptides

Micro-tip-based solid-phase microextraction is considered as one of the green and powerful analytical sample preparation techniques, but its efficiency is severely hampered by some basic issues such as tedious fabrication, instability of sorbent bed, and blocking of the tip, especially for biological samples due to low permeability. These issues are tackled by introducing a flexible and hierarchical substrate in the microtip, having good mechanical strength and specific functionality to capture the desired biomolecules. Considering the well-ordered and flexible structure of melamine foam, it was used as a substrate and for hydrophilic interaction chromatography (HILIC). Metal-organic framework, due to its excellent characteristics, was grafted on its surface anchored by self-assembling polydopamine. The resulting material was characterized and packed in the tip by just pressing the material in the conical structure of the tip. This affinity tip established good and tunable permeability and was used to selectively enrich glycopeptides as well as phosphopeptides. The affinity tip demonstrated excellent performance to enrich glycopeptides and phosphopeptides with a low limit of detection up to 0.5 fmol μL−1 from tryptic digests of horseradish peroxidase and β-Casein, respectively, and was stable up to 5 rounds of enrichment. Moreover, this affinity-tip also exhibited high selectivity up to up to 1:1000 (HRP digest to BSA digest) for glycopeptides and 1:200 (β-Casein digest to BSA digest) for phosphopeptides and demonstrated several other fascinating characteristics such as; excellent size exclusion effect for the omission of large-sized proteins, modest backpressure, reproducibility, reusability, smooth enrichment, and successfully applied to a human saliva sample.

Development of a Microfluidic Platform for Trace Lipid Analysis.

The inherent trace quantity of primary fatty acid amides found in biological systems presents challenges for analytical analysis and quantitation, requiring a highly sensitive detection system. The use of microfluidics provides a green sample preparation and analysis technique through small-volume fluidic flow through micron-sized channels embedded in a polydimethylsiloxane (PDMS) device. Microfluidics provides the potential of having a micro total analysis system where chromatographic separation, fluorescent tagging reactions, and detection are accomplished with no added sample handling. This study describes the development and the optimization of a microfluidic-laser induced fluorescence (LIF) analysis and detection system that can be used for the detection of ultra-trace levels of fluorescently tagged primary fatty acid amines. A PDMS microfluidic device was designed and fabricated to incorporate droplet-based flow. Droplet microfluidics have enabled on-chip fluorescent tagging reactions to be performed quickly and efficiently, with no additional sample handling. An optimized LIF optical detection system provided fluorescently tagged primary fatty acid amine detection at sub-fmol levels (436 amol). The use of this LIF detection provides unparalleled sensitivity, with detection limits several orders of magnitude lower than currently employed LC-MS techniques, and might be easily adapted for use as a complementary quantification platform for parallel MS-based omics studies.

Novel semi-automated graphene nanosheets based pipette-tip assisted micro-solid phase extraction as eco-friendly technique for the rapid detection of emerging environmental pollutant in waters

In this work, a new semi-automated syringe infusion-pump assisted graphene nanosheets (GNSs) based pipette-tip micro-solid phase extraction (PT-μSPE) as a green sample preparation technique was demonstrated for the sensitive analysis of emerging environmental pollutant in environmental waters using HPLC-UV. Microwave-assisted synthesized GNSs powder was packed into a 100 μL pipette-tip (as PT-μSPE cartridge) connected with a commercial plastic syringe (contains water sample). This setup was attached to a programmable auto-syringe infusion pump for the GNSs-PT-μSPE process. Triclosan (TCS) is an emerging environmental pollutant chosen as a target analyte to examine the extraction capacity and feasibility of GNSs as a sorbent material for PT-μSPE. Parameters affecting the extraction capability were systematically evaluated and thoroughly optimized. At optimized experimental parameters, excellent linearity (r2 = 0.9979) was achieved over the concentration range of 2–250 ng mL−1 for TCS, with a detection limit of 0.5 ng mL−1. Applicability of the presented method was examined with real water samples, and extraction recoveries obtained were ranged between 94.6–102.4% with RSD less than 7.8%. The presented protocol is a simple, semi-automated, eco-friendly, low-cost, and efficient sample pretreatment technique for quick analysis of TCS in environmental wastewaters.

Green sample preparation of alternative biosamples in forensic toxicology

Forensic toxicology is the scientific field that is associated with death investigations, matters involving drugs determination, sports doping etc. In forensic toxicology, reliable qualitative and quantitative toxicological analysis of a wide variety of drugs with different chemical properties (e.g., amphetamines, benzodiazepines, cannabis and opiates) is required. Alternative biosamples including hair, nails, saliva, sweat, cerebrospinal fluid and dried blood spots can be efficiently used in forensic toxicology to provide necessary or additional information. These samples exhibit certain benefits towards conventional blood and urine samples, such as ease in collection, stability, and provision of useful information for a long time period. Gas chromatography and liquid chromatography coupled with mass detectors or tandem mass detectors are the most powerful instrumentations for the determination of analytes of interest in forensic toxicology. Sample preparation is required to make the analyte compatible with these instrumentations, to remove matrix interferences and to preconcentrate them. For this purpose, solid-phase extraction (SPE) and liquid-liquid extraction (LLE) have been widely used. However, since the development of green analytical chemistry that emerged from green chemistry, a plethora of microextraction and miniaturized extraction techniques have been developed. In this review article we aim to discuss the green sample preparation techniques of alternative biosamples in forensic toxicology reported during the last 10 years.

Microwave-assisted extraction and matrix solid-phase dispersion as green analytical chemistry sample preparation techniques for the valorisation of mango processing waste

Food supply chain waste is consisted not only by the visible part generated in commercial and consumer steps, but also by the residues generated during harvesting and processing of food-related plants. A great part of these materials is unavoidable, meaning that they cannot be prevented trough waste reduction policies currently being pushed to achieve better food distribution and end hunger across the globe. Valorising this waste stream may help increasing stability in the food sector, having not only a financial gain, but also an environmental and social positive impact. Mango Processing Waste (MPW) is one of the examples of how such residues are poorly explored, as its large volumes contain several valuable substances, such as bioactive compounds, that can be used in the food industry as ingredients and as nutraceuticals, pesticides in agriculture, biocides and other uses. The flavonol hyperoside and the xanthone mangiferin are the main secondary metabolites found in MPW, being reported to have biological activities that range from antioxidant to pesticidal and pharmacological potential uses. In a broader context considering the use of MPW in a biorefinery and circular economy concepts, sustainable processes are required to meet future sustainability parameters. Therefore, Microwave-Assisted Extraction (MAE) and Matrix Solid-Phase Dispersion (MPSD), two sample preparation techniques, were discussed and studied as proposed green and sustainable methodologies for the extraction of mangiferin and hyperoside from MPW. Doehlert and Box-Behnken experimental designs were used to help assessing the influences of the variables of each technique, allowing to employ a Response Surface Methodology (RSM) to visualize the best conditions and calculate optimum parameters. Fast extraction was achieved using MAE, which obtained maximum response of 261.39 mg kg −1 of mangiferin and 244.44 mg kg −1 of hyperoside. Higher yields were obtained using MSPD methodology, with an extraction yield of 352.90 mg kg −1 and 398.52 mg kg −1 of mangiferin and hyperoside, respectively. The conditions that allowed maximum simultaneous extraction concentrations were calculated using the desirability function. MAE and MSPD methodologies were compared, with an overall conclusion that both were adequate for the determination of the two analytes and can be further studied to be used in higher scales.

In-situ kinetic and thermodynamic study of 2,4-dichlorophenoxyacetic acid adsorption on molecularly imprinted polymer based solid-phase microextraction coatings

Solid-phase microextraction (SPME) is attracting increasing interest due to being promising, new and green sample-preparation technique. Despite the vast research on the SPME, little is known about adsorption kinetics and thermodynamics of SPME coating, which plays the key role in the extraction. In this paper, a blade type SPME coating was prepared on glass slide, and 2,4-dichlorophenoxyacetic acid (2,4-D) adsorption on the coating were monitored by in-situ fiber-optic sensing. The effects of contact time, temperature (298-318 K) and initial concentration (20-150 mg/L) of 2,4-D on the adsorption properties of SPME coating were discussed. The results demonstrated that the pseudo-second-order model was most suitable for describing 2,4-D adsorption on the SPME coating. The thermodynamic parameters (ΔH, ΔS, ΔG) indicate that 2,4-D adsorption at low concentration by the SPME coating is exothermic and spontaneous process. Under the same conditions, the molecularly imprinted polymers (MIPs) coating have significantly higher adsorption capacity, and faster adsorption rate than the non-imprinted polymers (NIPs) SPME coating. This approach provides a tool for in-situ monitoring of adsorption kinetics and thermodynamics of SPME coating which requires fast measurement and small volume.

Development of Alternative Green Sample Preparation Techniques

Although chemistry disciplines are often regarded by the public as polluting sciences, in the last three decades, the concept of “Green Chemistry” has fueled the development of more sustainable and environmentally friendly chemical processes that are mainly aimed at minimizing the production of toxic laboratory waste, to maximize pollution prevention [...]

Polymeric ionic liquid sorbent coatings in headspace solid-phase microextraction: A green sample preparation technique for the determination of pesticides in soil

In this work, a green approach utilizing novel polymeric ionic liquid (PIL) coatings for headspace solid-phase microextraction (HS-SPME) of four current-use pesticides from soil samples was studied for the first time. Epoxiconazole, fluroxypyr, metribuzin, and oxyfluorfen were the target pesticides. Three PIL coatings containing 1-vinylbenzyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide (PIL1 and PIL2) and 1-vinyl-3-(10-hydroxydecyl)imidazolium bis[(trifluoromethyl)sulfonyl]imide (PIL3) monomers, and 1,12-di(3-vinylbenzylimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide (PIL1) and 1,12-di(3-vinylbenzimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide (PIL2 and PIL3) crosslinkers were employed in this study. The performance of these PIL coatings was evaluated and compared with commercial SPME coatings based on polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polydimethylsiloxane (PDMS) at the different extraction temperatures (50–90 °C) and sampling times (15–60 min). HS-SPME at 90 °C for 60 min provided the highest sensitivity and adequate reproducibility for the majority of analytes. Despite having a lower thickness, PIL2 and PIL3 coatings provided similar extraction effectiveness of analytes, and 24–247% higher coating volume-normalized responses compared to the commercial PDMS/DVB coating. The use of the PIL1 sorbent coating resulted in excellent linearity (R2 = 0.995–0.999) and lower detection limits (0.06–0.4 ng g−1) for all analytes. The optimized method provides acceptable recoveries of spiked concentrations with better performance (84–112%) achieved with the PIL1 coating. Compared to other known methods for target pesticides in soil, the proposed method provides the highest compliance with the principles of green analytical chemistry evaluated using Analytical Eco-Scale and Green Analytical Procedure Index tools.

Capillary electrophoresis with field-amplified sample stacking for simultaneous determination of indacaterol and glycopyrronium in inhaler capsules: Application to human plasma and urine

A sensitive, simple and rapid capillary electrophoresis method for the simultaneous determination of indacaterol and glycopyrronium was developed and validated. The separation was achieved within 5 min using 65 mM phosphate buffer at pH 5.5 under an applied voltage of 18 kV and UV detection at 195 nm. To enhance the sensitivity, field-amplified sample stacking was adopted. The main parameters that affected separation and stacking efficiency were investigated. The method showed good linearity in the ranges 20-800 ng/mL for both analytes with LODs of 3.63 and 2.84 ng/mL for indacaterol and glycopyrronium, respectively. The method was successfully applied in analysis of indacaterol and glycopyrronium both individually and in a combined dosage inhaler capsules. In addition, ultrasound extraction as a green sample preparation technique for their determination in spiked human plasma and urine with good recovery was evaluated.

Evaluation of Green Sample Preparation Techniques for Organic Compounds

Nowadays, Green Analytical Chemistry (GAC) idea is of high importance, with impact on the rapid growth in the sample preparation area with special emphasis on sample preparation simplification, miniaturization and automation. Due to the fact that GAC is of high importance today, this study is focused on the evaluation of green sample preparation techniques for organic compounds. It is well known that sample preparation is considered a crucial part of analytical procedures, particularly in samples characterized by complex matrices composition. The parameter of “greenness” is as important as selectivity in order to avoid using harmful organic solvents in sustainable extraction techniques. These solvents can generate hazardous, toxic waste while consuming large resources volume, thus, developing new, eco-friendly and benign solvents which would meet technological and economic demands is perhaps the most popular aspects of Green Chemistry. Some examples of these “green” solvents are given in this work. In addition, several new miniaturized extraction techniques are described. Here you can highlight solid phase microextraction (SPME) and liquid phase microextraction (LPME). However, the best option would be to use direct methods of analysis, where sample preparation is not required. The given study also shows the possibilities and limitations of using Eco-Scale and GAPI tools for the assessment of the green character of selected analytical procedures. Both tools were applied to assess 9 different analytical procedures and both showed similar results presented in a different manner.

Recent applications of on-line supercritical fluid extraction coupled to advanced analytical techniques for compounds extraction and identification.

In a previous review (Sánchez-Camargo etal., J. Sep. Sci. 40 (2017) 213-227), we discussed the application of on-line supercritical fluid extraction coupled to chromatographic techniques. This review includes an update of the most recent publications (from January 2016 till June 2018) on this topic, which employs advanced analytical techniques for extracting and identifying valuable analytes. Supercritical fluid extraction has been widely recognized as a green sample preparation technique, because it is efficient, environmentally friendly, powerful, and faster, offering the possibility of direct coupling to analytical instrumental techniques. Among those techniques, supercritical fluid chromatography has experienced an innovative progression in the last 10 years, and the most recent applications of supercritical fluid extraction are coupled to this advanced analytical tool. The general principles, both methodological and instrumental of on-line supercritical fluid extraction coupled to supercritical fluid chromatography are described here. Besides, applications of the mentioned coupling for analysing biological fluids, food, soil, and botanical samples are also presented and discussed. Finally, a brief description about the very recent on-line coupling of supercritical fluid extraction to ion mobility spectrometry is presented, as well as concluding remarks about the importance of using these coupled techniques in the near future.

Fabric Phase Sorptive Extraction: Current State of the Art and Future Perspectives

Fabric phase sorptive extraction (FPSE) is a novel and green sample preparation technique introduced in 2014. FPSE utilizes a natural or synthetic permeable and flexible fabric substrate chemically coated with a sol-gel organic-inorganic hybrid sorbent in the form of ultra-thin coating, which leads to a fast and sensitive micro-extraction device. The flexible FPSE requires no modification of samples and allows direct extraction of analytes. Sol-gel sorbent-coated FPSE media possesses high chemical, solvent, and thermal stability due to the strong covalent bonding between the substrate and the sol-gel sorbent. Therefore, any elution solvent can be used in a small volume, which achieves a high pre-concentration factor without requiring any solvent evaporation and sample reconstitution step. Taking into consideration the complexity of the samples and the need of further minimization and automation, some new, alternative modes of the FPSE have also been developed. Therefore, FPSE has attracted the interest of the scientific community that deals with sample pre-treatment and has been successfully applied for the extraction and determination of many analytes in environmental samples as well as in food and biological samples. The objective of the current review is to present and classify the applications of FPSE according to different sample categories and to briefly show the progress, advantages, and the main principles of the proposed technique.