Deep eutectic solvent magnetic bucky gels in developing dispersive solid phase extraction: Application for ultra trace analysis of organochlorine pesticides by GC-micro ECD using a large-volume injection technique

Simultaneous effervescence-assisted microextraction and magnetic adsorbent generation for rapid and cost-effective organochlorine pesticides analysis

This study introduced an innovative magnetic effervescence-assisted microextraction method, streamlining the preparation of effervescent tablets through a one-pot method that blends a CO2 donor (Na2CO3) and an H+ donor (NaH2PO4) with bare magnetic particles (Fe3O4) and an adsorbent (hydroxylated multi-walled carbon nanotubes), followed by pressing. During the extraction process, the bare magnetic particles and adsorbent undergo in-situ self-assembly to create a magnetic adsorbent. The effervescence generates bubbles that enhance effective extraction and magnetism facilitates the easy separation of the magnetic adsorbent from the sample solution, completing the process within 4 min. Applied to organochlorine pesticide analysis in fruit juices and herbal extracts, the method exhibits excellent linearity (R2 > 0.993), sensitivity (detection limits: 0.010-0.125 ng/mL), accuracy (recoveries: 85.8-99.9%), and precision (RSDs < 9.7%) with GC-ECD. Overall, this approach stands out for its simplicity, cost-effectiveness, and suitability for on-site analysis, owing to its operational ease and independence from specialized equipment.

A sensitive determination of Brilliant Blue FCF in some food samples using hydrophillic deep eutectic solvent-assisted magnetic nano gel-based dispersive solid phase microextraction prior to spectrophotometric analysis

A new magnetic nano gel (MNG) was prepared from choline chloride/phenol deep eutectic solvent and magnetic amberlite XAD-7 nanocomposite. The dispersive solid phase micro extraction (dSPME) method was developed for seperation and preconcentration of Brilliant Blue FCF (BB) by the prepared MNG. In this study, firstly, the optimum DES type and mole ratio of DES were investigated before response surface methodology optimization. Then, the effect of the MNG-dSPME experimental parameters were optimized by response surface methodology using central composite design. Under the optimum microextraction conditions, limit of detection (LOD), limit of quantification (LOQ), preconcentration factor (PF), enhencament factor (EF) were found to be 1.15 μg L-1,3.80 µg L-1, 70, and 88, respectively. It was seen that the recovery of real samples were obtained from 95.5 to 103.6%. The pesent method was succesfully for extraction of BB in some food, personal care samples, to the best of our knowledge, this is the first study that is presented method on determination of BB by preconcentration with magnetic nano gel. The obtained results showed that the present procedure is effective, sensitive, and has high accuracy for the quantitative detection of BB.

Deep eutectic solvents with solid supports used in microextraction processes applied for endocrine-disrupting chemicals

The determination of endocrine-disrupting chemicals (EDCs) has become one of the biggest challenges in Analytical Chemistry. Due to the low concentration of these compounds in different kinds of samples, it becomes necessary to employ efficient sample preparation methods and sensitive measurement techniques to achieve low limits of detection. This issue becomes even more struggling when the principles of the Green Analytical Chemistry are added to the equation, since finding an efficient sample preparation method with low damaging properties for health and environment may become laborious. Recently, deep eutectic solvents (DESs) have been proposed as the most promising green kind of solvents, but also with excellent analytical properties due to the possibility of custom preparation with different components to modify their polarity, viscosity or aromaticity among others. However, conventional extraction techniques using DESs as extraction solvents may not be enough to overcome challenges in analysing trace levels of EDCs. In this sense, combination of DESs with solid supports could be seen as a potential solution to this issue allowing, in different ways, to determine lower concentrations of EDCs. In that aim, the main purpose of this review is the study of the different strategies with solid supports used along with DESs to perform the determination of EDCs, comparing their advantages and drawbacks against conventional DES-based extraction methods.

Applications of deep eutectic solvents in microextraction and chromatographic separation techniques: Latest developments, challenges, and prospects

Deep eutectic solvents (DESs) have recently sparked considerable attention in a variety of scientific and technological fields. The unique properties of DESs include biodegradability, easy preparation, low cost, and tuneability, rendering them a new and prospective alternative to hazardous solvents. Analytical chemistry is one of the most appealing fields where DESs proved to be applicable in either sample preparation or chromatographic separation. This review summarizes the new horizons dedicated to the application of DESs in microextraction and chromatographic separation. The utilization of DESs in microextraction, in chromatography as mobile phase additives, and in chromatographic material preparation processes is outlined. The enhancements in chromatographic performance achieved using DESs and any potential explanations deduced from the experimental findings were primarily discussed. An additional brief discussion on DESs preparation, characterization, and properties is addressed in this work. Finally, current challenges and future trends are also presented, supplying evidence for distinct possibilities regarding new research approaches involving DESs. This review can represent a guide and stimulate further research in this field.

An efficient deep eutectic magnetic nano gel for rapid ultrasound-assisted dispersive µ-solid phase extraction of residue of tetracyclines in food samples

In the present study, a magnetic nano gel as the sorbent which is the combination of octatonic acid: cumarin as eutectic solvent and Fe3O4@SiO2 was introduced as the sorbent in ultrasound-assisted dispersive µ-solid phase extraction process coupled with high performance liquid chromatography with photo diode array detector for simultaneous separation and determination of tetracyclines residues in food samples. FT-IR, SEM, VSM were used for the characterization of the synthetized magnetic nano gel. Under obtained optimum conditions, the obtained linear ranges were 1.5-500 (µg L-1), 2.5-750 (µg L-1), 2-750 (µg L-1), and 2.5-500 (µg L-1) for tetracycline, oxytetracycline, chlortetracycline, and doxycycline, respectively. Moreover, the below level of quantification (BLQ) (based on S/N = 3) of 0.47 µg L-1, 0.11 µg L-1, 0.85 µg L-1, 0.66 µg L-1, 0.81 µg L-1 and the limit of quantification (based on S/N = 10) of 1.61, 2.74, 2.23 (µg L-1), and 2.66 were achieved for tetracycline, oxytetracycline, chlortetracycline, and doxycycline, respectively. The intra-day and inter-day precision (%) of the procedure were less than 3.2 and 3.8, respectively. The recoveries over 95% confirmed high sufficiency of the proposed method for application in complex matrices such as honey, milk, and egg.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05798-w.

Deep eutectic solvent coated paper: Sustainable sorptive phase for sample preparation

Paper-based sorptive phases have gained attention recently due to the low-cost and sustainable character of the cellulosic substrate. However, the sustainability of the resulting phase can be limited by type of coating used for analytes isolation. In this article, this limitation is overcome by using deep eutectic solvents (DES) as coating. To this aim, a Thymol-Vanillin DES is synthesized and deposited on pre-cut cellulose paper strips. The paper-supported DES is employed as sorptive phase for the isolation of selected triazine herbicides for environmental waters analysis. The isolated analytes are finally determined by gas chromatography-mass spectrometry using selected ion monitoring. The method is optimized according to the critical variables that potentially affect its analytical performance such as sample volume, extractant amount, extraction time and sample ionic strength. The method was characterized in terms of sensitivity, accuracy and precision and its applicability was evaluated for the analysis of real environmental water samples. Good linearity values (R²>0.995) were obtained for all the analytes. Limits of detection (LODs) ranged from 0.4 to 0.6 µg L^-1 and the precision, expressed as relative standard deviation (RSD) was better than 14.7%. The relative recoveries, calculated in spiked well and river samples, were in the range 90-106%.

Comparison of the extractability of organophosphorus flame retardants in landfill media using organic and green solvents

Organic solvents are mainly used in the extraction of organophosphorus flame retardants (OPFRs) because of their availability and having been tested as good extracting solvents for most environmental pollutants. However, organic solvents are toxic, flammable, and costly. Hence, there is an ongoing quest for less hazardous chemicals such as green deep eutectic solvents (DES) that are cheap, recyclable, non-toxic and degradable in the environment, which can be used to extract organic pollutants such as OPFRs in environmental samples. This study assessed the extractability of OPFRs in municipal landfill leachate and sediment, using organic solvents and DES. Of the fourteen targeted OPFRs, 11 (80%) and 7 (50%) were detected in the leachate and sediment samples, using hexane; whereas 14 (100%) and 13 (90%) OPFRs were detected in the same order of samples using DES. The concentrations of OPFRs obtained for the leachate using optimum organic and DES ranged from below the limit of quantification (< LOQ)—516 ± 8.10 ng/L and < LOQ—453 ± 8.10 ng/L respectively. Correspondingly, the concentrations of OPFRs in sediment samples ranged from < LOQ—135 ± 2.89 ng/g dw and < LOQ—395 ± 2.24 ng/g dw, respectively. The results from this study, therefore, highlight the potential of DES to extract more OPFR from complex matrices such as landfill leachate and sediment. This finding infers that green hydrophilic DES can serve as good replacement for organic solvents such as hexane in liquid–liquid extraction (LLE) and solid–liquid extraction (SLE) techniques for landfill leachate and sediment.

Analysis of anticancer compound, indole-3-carbinol, in broccoli using a new ultrasound-assisted dispersive-filter extraction method based on poly(deep eutectic solvent)-graphene oxide nanocomposite

Indole-3-carbinol (I3C), an important anticancer compound found in broccoli, has attracted considerable attention. The rapid extraction and accurate analysis of I3C in the pharmaceutical industry in broccoli is challenging as I3C is unstable at low pH and high temperature. In this study, a rapid, accurate, and low-cost ultrasound-assisted dispersive-filter extraction (UADFE) technique based on poly(deep eutectic solvent)-graphene oxide (PDES-GO) adsorbent was developed for the isolation and analysis of I3C in broccoli for the first time. PDES-GO with multiple adsorption interactions and a fast mass transfer rate was synthesized to accelerate adsorption and desorption. UADFE was developed by combining dispersive solid-phase extraction (DSPE) and filter solid-phase extraction (FSPE) to realize rapid extraction and separation. Based on the above two strategies, the proposed PDES-GO-UADFE method coupled with high-performance liquid chromatography (HPLC) allowed the rapid (15-16 min), accurate (84.3%-96.4%), and low-cost (adsorbent: 3.00 mg) analysis of I3C in broccoli and was superior to solid-phase extraction, DSPE, and FSPE methods. The proposed method showed remarkable linearity (r=0.9998; range: 0.0840-48.0 μg/g), low limit of quantification (0.0840 μg/g), and high precision (relative standard deviation ≤5.6%). Therefore, the PDES-GO-UADFE-HPLC method shows significant potential in the field of pharmaceutical analysis for the separation and analysis of anti-cancer compounds in complex plant samples.

New and efficient magnetic nanocomposite extraction using multifunctional deep eutectic solvent based on ferrofluid and vortex assisted-liquid-liquid microextraction: Determining primary aromatic amines (PAAs) in tetra-packed fruit juices

In this work, a novel magnetic nanocomposite solvent (MNCS) based on ferrofluid and multifunctional deep eutectic solvent (MDES) was synthesized and applied in vortex assisted-liquid-liquid microextraction (VA-LLME). The ferrofluid has been composed from zirconium phosphate (modified magnetic graphene oxide) and tetrabutylammonium bromide-octanoic acid deep eutectic solvent (MGO/α-ZrP@TBAB-OA). This efficient method was employed to determine primary aromatic amines including aniline, 4-methoxyanniline, 4,4'-diaminodiphenylmethane, orthotoluidine, 2,6-dimethylaniline, 2-naphtylamine in tetra-packed juice samples. The proposed method showed the excellent extraction efficiency of PAAs according to strong interactions of new extraction solvent including electrostatic, π-π, and hydrogen bonding attractions. The found levels of PAAs are lower than the limit of quantifications (2.0 µg L^-1). Therefore, the migration of PAAs from packaging to the juice samples is lower than permitted level (<10 µg kg^-1). The results indicated high potential use of the offered method to analyze aromatic amine compounds in foodstuff and biologic samples in the future.

Exploring a novel deep eutectic solvents combined with vortex assisted dispersive liquid-liquid microextraction and its toxicity for organophosphorus pesticides analysis from honey and fruit samples

A novel deep eutectic solvents (DES) was successfully applied as an emulsifier in vortex assisted liquid-liquid microextraction (VALLME) coupled with gas chromatography-mass spectrometry for the determination of organophosphorus pesticides in honey and fruit samples. Based on the result of toxicity study, DES provides new opportunities for the safe delivery and application. The predominant parameters affecting extraction efficiency were thoroughly optimized and studied in detail. Under optimum parameters, the calibration curve was determined in the concentration range of 0.1 to 200 µgL^-1 with excellent determination coefficients values of 0.9989 to 0.9999. Limit of detection and limit of quantification were found to be 0.01 - 0.09 µgL^-1 and 0.03 - 0.2 µgL^-1, respectively. Application of the developed method to honey and fruit samples gave acceptable recovery values 83 - 109% with relative standard deviation below than 9.5%. The suggested approach has also proven to be simple, cost-effective, rapid, and non-toxic in nature.

Establishment of Deep-Eutectic-Solvent-Assisted Matrix Solid-Phase Dispersion Extraction for the Determination of Four Flavonoids in Scutellariae Radix Based on the Concept of Quality by Design

BACKGROUND

Sample preparation is the most crucial step in analytical schemes. Micro-matrix solid-phase dispersion, as a method for microextraction of analytes, has prevailed recently for its low sample and extraction solvent consumption. However, small amounts of adsorbent or sample, or a short extraction time, always bring uncertainty to the result when using this method.

OBJECTIVE

The aim was to develop a simple and reliable method of deep-eutectic-solvent-assisted ultrasonic-synchronized matrix solid-phase dispersion microextraction for the analysis of four flavonoids in Scutellariae Radix based on the concept of quality by design.

METHOD

The ZSM-5 molecular sieve was used as a new adsorbent in the micro-matrix solid-phase dispersion process. Single-factor and Box-Behnken designs were used to construct the design space.

RESULTS

Verification of the experiment demonstrated that the design space is robust. Under optimal conditions, all analytes showed good linearity (R2 > 0.999), high reproducibility (RSD < 2.24%) and stability (RSD < 2.87%), and satisfactory recoveries (95.90-102.31%), which indicated that the established method is reliable and reproducible. Moreover, it has been successfully applied to determine the flavonoids in nine batches of Scutellariae Radix.

CONCLUSIONS

The results indicate a great potential for analyzing complicated samples especially with small amount and helping to promote the quality control of the sample preparation process for traditional Chinese medicines.

HIGHLIGHTS

A systematic approach using a facile deep-eutectic-solvent-assisted ultrasonic-synchronized matrix solid-phase dispersion extraction coupled with HPLC for the analysis of flavonoids in Scutellariae Radix has been developed based on the concept of quality by design.

Deep eutectic solvent-modified mixed iron hydroxide-silica: Application in magnetic solid-phase extraction for enrichment of organochlorine pesticides prior to GC-MS analysis

A new type of magnetic material based on silica-coated mixed iron hydroxides functionalized with deep eutectic solvent was utilized for the magnetic solid-phase extraction of organochlorine pesticides prior to gas chromatography-mass spectrometry analysis. Choline chloride and phenol were selected as the hydrogen bond acceptor and donor, respectively, for preparing the deep eutectic solvent-modified magnetic surface. The modified surface possessed superior enrichment capability for organochlorine pesticides. Under optimal extraction conditions, viz., 10 mg sorbent, 5 mL sample solution, and 200 μL acetone (desorption solvent), linearity was obtained in the range 0.005-200 μg/L, with coefficients of determination greater than 0.997. The limits of detection and quantification were as low as 0.6-10 and 5-60 ng/L, respectively, whereas the enrichment factors were in the range of 31-100. The precisions evaluated in terms of the relative standard deviations of the intra- and inter-day experiments were <4.9 and 7.6%, respectively. The developed method was successfully applied for determining the organochlorine residues in agricultural products. Satisfactory recoveries in the range of 71.2-110.3% were obtained, with a relative standard deviation of <8.0%. The proposed material is a promising sorbent for the preconcentration of organochlorine residues.

Recent Applications of Deep Eutectic Solvents in Environmental Analysis

The incessant generation of toxic waste and the growing concern over the environment have led the scientific community to delve into the search for more sustainable systems. In this regard, the application of deep eutectic solvents (DESs) has become one of the main strategies in green chemistry. These solvents have emerged as a promising alternative to conventional toxic solvents and even to the well-known ionic liquids. Their unique properties, components availability, and easy preparation, among others, have led to a new trend within the scientific community and industry, based on the use of these up-and-coming solvents not only in science but also in quotidian life. Among the areas that have benefited from the advantages of DESs is analytical chemistry, in which they have been largely used for sample preparation, including the extraction and determination of organic and inorganic compounds from environmental samples. The considerable number of applications developed in the last year in this field and the increasing generation of new data necessitate the continuous updating of the literature. This review pretends to compile the most relevant applications of DESs in environmental analysis and critically discuss them to provide a global vision about the advantages and drawbacks/limitations of these neoteric solvents in the area of environmental analysis.

Solid-phase microextraction of eleven organochlorine pesticides from fruit and vegetable samples by a coated fiber with boron nitride modified multiwalled carbon nanotubes

A boron nitride modified multiwalled carbon nanotube material (BN@MWCNTs) was synthesized, and the synthesis conditions were optimized. The BN@MWCNTs was then used as the SPME fiber coating adsorbent for the extraction of eleven organochlorine pesticides (OCPs) from fruit and vegetable samples. Under the optimal conditions, the SPME coupled with the detection by GC-ECD had a linear response for the determination of the target analytes in the range of 0.03 to 200 ng g^-1 with the coefficients of determination (r²) ≥ 0.9977. Based on the signal-to-noise ratios of 3 and 10, the limits of detection and the limits of quantification were measured to be 0.01-0.20 ng g^-1 and 0.03-0.67 ng g^-1, respectively. The relative recoveries of the analytes for spiked samples under three concentration levels (1.0, 10.0 and 100 ng g^-1) were between 83.7% and 124% with the relative standard deviations ≤ 10.9%. The established method was successfully applied to the determination of OCPs in real fruit and vegetable samples.

Deep eutectic solvent-based emulsification liquid-liquid microextraction for the analysis of phenoxy acid herbicides in paddy field water samples

An emulsification liquid-liquid microextraction (ELLME) method was successfully developed using phenolic-based deep eutectic solvent (DES) as an extraction solvent for the determination of phenoxy acid herbicides, 3,6-dichloro-2-methoxybenzoic acid (dicamba) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in environmental water samples. Five different phenolics-based DESs were successfully synthesized by using phenol (DES 1), 2-chlorophenol (DES 2), 3-chlorophenol (DES 3), 4-chlorophenol (DES 4) and 3,4-dichlorophenol (DES 6) as the hydrogen-bond donor (HBD) and choline chloride as the hydrogen-bond acceptor (HBA). The DESs were mixed at 1 : 2 ratio. A homogeneous solution (clear solution) was observed upon the completion of successful synthesis. The synthesized DESs were characterized by using Fourier transform infrared and nuclear magnetic resonance (NMR). Under optimum ELLME conditions (50 µl of DES 2 as extraction solvent; 100 µl of THF as emulsifier solvent; pH 2; extraction time 5 min), enrichment factor obtained for dicamba and MCPA were 43.1 and 59.7, respectively. The limit of detection and limit of quantification obtained for dicamba were 1.66 and 5.03 µg l-1, respectively, meanwhile for MCPA were 1.69 and 5.12 µg l-1, respectively. The developed ELLME-DES method was applied on paddy field water samples, with extraction recoveries in the range of 79-91% for dicamba and 82-96% for MCPA.

Exploring the use of cork pellets in bar adsorptive microextraction for the determination of organochloride pesticides in water samples with gas chromatography/electron capture detection quantification

In this study, a biosorbent material with characteristics for the adsorption of organic compounds was used for a cork pellet-based bar adsorptive microextraction technique, as a new greener alternative for the determination of organochlorine compounds. Aldrin, chlordane, dieldrin, endrin, lindane, 4,4-DDD, 4,4-DDE, 4,4-DDT, α-endosulfan and β-endosulfan were analyzed in water samples (drinking water, stream water and river water) with separation/detection by gas chromatography and electron capture detection (GC/ECD). The parameters that can affect the sample preparation efficiency such as desorption solvent and time as well as extraction time and ionic strength were evaluated by multivariate and univariate designs. Cork pellets (10  ×  Ø 3 mm) were used for the extraction of 15 mL of sample in the optimal conditions: 60 min of agitation with no salt added to the sample, followed by desorption of the cork pellet with 120 µL of ethyl acetate for 30 min. The bar-to-bar RSD out with five different bars showed good results with RSD ≤ 15.6%, allowing the use of simultaneous extractions. LOD and LOQ values ranged from 3 to 15 ng L^-1 and 10 to 50 ng L^-1 respectively, and the determination coefficients were greater than 0.9869. The target analytes were not detected in the three analyzed samples. Therefore, the recovery study was performed fortifying the water samples. Analyte recovery ranged from 48.7 - 138.2% for drinking water, 40.2 - 128.2% for stream water and 67.5 - 128.7% for river water.

Advanced Functional Nanostructures based on Magnetic Iron Oxide Nanomaterials for Water Remediation: A Review

The fast growth of industrialization combined with the increasing population has led to an unparalleled demand for providing water in a safe, reliable, and cost-effective way, which has become one of the biggest challenges of the twenty-first century faced by global society. The application of nanotechnology in water treatment and pollution cleanup is a promising alternative in order to overcome the current limitations. In particular, the application of magnetic iron oxide nanoparticles (MIONs) for environmental remediation has currently received remarkable attention due to its unique combination of physicochemical and magnetic properties. Given the broadening use of these functional engineered nanomaterials, there is a growing concern about the adverse effects upon exposure of products and by-products to the environment. This makes vitally relevant the development of green chemistry in the synthesis processes combined with a trustworthy risk assessment of the nanotoxicity of MIONs as the scientific knowledge of the potential hazard of nanomaterials remains limited. This work provides comprehensive coverage of the recent progress on designing and developing iron oxide-based nanomaterials through a green synthesis strategy, including the use of benign solvents and ligands. Despite the limitations of nanotoxicity and environmental risks of iron oxide-based nanoparticles for the ecosystem, this critical review presents a contribution to the emerging knowledge concerning the theoretical and experimental studies on the toxicity of MIONs. Potential improvement of applications of advanced iron oxide-based hybrid nanostructures in water treatment and pollution control is also addressed in this review.

Nanoparticles Based Extraction Strategies for Accurate and Sensitive Determination of Different Pesticides

Sample preparation methods have become indispensable steps in analytical measurements not only to lower the detection limit but also to eliminate the matrix effect although more sophisticated instruments are being commonly used in routine analyses. Solid phase extraction (SPE) is one of the main extraction/preconcentration methods used to extract and purify target analytes along with simple and rapid procedures but some limitations have led to seek for an easy, sensitive and fast extraction methods with analyte-selective sorbents. Nanoparticles with different modifications have been used as spotlight to enhance extraction efficiency of target pesticides from complicated matrices. Carbon-based, metal and metal oxides, silica and polymer-based nanoparticles have been explored as promising sorbents for pesticide extraction. In this review, different types of nanoparticles used in the preconcentration of pesticides in various samples are outlined and examined. Latest studies in the literature are discussed in terms of their instrumental detection, sample matrix and limit of detection values. Novel strategies and future directions of nanoparticles used in the extraction and preconcentration of pesticides are also discussed.

Are deep eutectic solvents useful in chromatography? A short review

A literature update has been done concerning Deep Eutectic Solvents (DES) use in chromatography applications. The literature survey was based on the period from 2010 till 2020 and manuscripts reported in the data bases Web of Science and Scopus. The use of DES as mobile phase and mobile phase additives, stationary phases and solid phase modifiers and the use of DES as reaction solvents for chromatography use, were evaluated. Emphasis was placed on the differentiation of DES and Ionic Liquids (ILs) and the advanced green characteristics of the new solvents as compared with traditional organic solvents and ILs with a look into the drawbacks and future perspectives in the field of separation methods.

Development of magnetic dispersive micro-solid phase extraction based on magnetic agarose nanoparticles and deep eutectic solvents for the isolation and pre-concentration of three flavonoids in edible natural samples

In the present study, an environmentally friendly magnetic dispersive micro-solid phase extraction was developed based on magnetic agarose nanoparticles and deep eutectic solvents for the isolation and pre-concentration of three flavonoids (morin, quercetin, and kaempferol) from dark tea, chocolate, vegetable, and fruit juice samples. In this method, deep eutectic solvents were synthesized from less toxic and low-cost substances under feasible conditions and used as eluents in the desorption process. These solvents can be considered as a green alternative to traditional organic reagents to increase the adsorption capacity and reduce the matrix interferences, dangerous waste generation and environmental pollution. A Plackett-Burman design was employed for screening the experimental variables. The effective variables were then optimized by Box-Behnken design (BBD). Under the optimial conditions, the presented method demonstrated wide linear ranges of 1-500 μg. L^-1 for morin and quercetin, and 5-500 μg. L^-1 for kaempferol with satisfactory recoveries above 91%. Limit of detections (LODs) and quantifications (LOQs) of flavonoids varied in 0.2-1.1 μg. L^-1 and 0.66-3.63 μg. L^-1, respectively. The precision of the proposed method was the range of 2.6-5.7%.

Magnetic Polydopamine Modified with Choline-Based Deep Eutectic Solvent for the Magnetic Solid-Phase Extraction of Sulfonylurea Herbicides in Water Samples

A novel magnetic solid-phase extraction technique coupled to ultraperformance liquid chromatography has been developed for separation and preconcentration of four sulfonylurea herbicides (sulfosulfuron, bensulfuron-methyl, pyrazosulfuron-ethyl and halosulfuro-methyl) in aqueous samples. The key point of this method was the application of a novel magnetic nanomaterial that composed of a low eutectic solvent as a shell coated on the magnetic core modified by polydopamine. The extensive active sites outside the low eutectic solvent can effectively adsorb the target herbicide in the extraction process. The obtained magnetic adsorbent was characterized with fourier transform infrared spectrometry, scanning electron microscopy and vibrating sample magnetometer. The influence parameters relevant to this method were optimized. Under the optimum conditions, good linearities could be obtained within the range of 1.0-200 μg L-1 for all analytes, with correlation coefficients ≥0.9908. The limit of detections of the method was between 0.0074 and 0.0100 μg L-1 and the relative standard deviations were 1.1-3.6%. The enrichment factor is 66.6. In the final experiment, the proposed method was successfully applied to the analysis of sulfonylurea herbicides residue in environment and drinking-water samples, and the obtained recoveries were between 70.6% and 109.4%.

Microextraction Techniques with Deep Eutectic Solvents

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.

Recent Materials Developed for Dispersive Solid Phase Extraction

Solid phase extraction (SPE) is an analytical procedure developed with the purpose of separating a target analyte from a complex sample matrix prior to quantitative or qualitative determination. The purpose of such treatment is twofold: elimination of matrix constituents that could interfere with the detection process or even damage analytical equipment as well as enriching the analyte in the sample so that it is readily available for detection. Dispersive solid phase extraction (dSPE) is a recent development of the standard SPE technique that is attracting growing attention due to its remarkable simplicity, short extraction time and low requirement for solvent expenditure, accompanied by high effectiveness and wide applicability. This review aims to thoroughly survey recently conducted analytical studies focusing on methods utilizing novel, interesting nanomaterials as dSPE sorbents, as well as known materials that have been only recently successfully applied in dSPE techniques, and evaluate their performance and suitability based on comparison with previously reported analytical procedures.

Poly (deep eutectic solvents) as a new class of sustainable sorbents for solid phase extraction: application for preconcentration of Pb (II) from food and water samples

A new class of polymeric sorbents based on deep eutectic solvents (DESs) is introduced. These materials are obtained from simple and inexpensive precursors via an energy-efficient process. The primary benefit of these sorbents is that they possess the unique characteristics of DESs and porous materials simultaneously. Moreover, the possibility of tailoring deep eutectic solvents allows designing a specific polymer for a desired analyte, based on its physical and chemical properties. In this work, the deep eutectic solvent of tetrabutylammonium bromide and acrylic acid (1:2 molar ratio) was prepared and then polymerized under solventless condition. The synthesized polymer was characterized by FT-IR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), and Brunauer, Emmett and Teller analysis (BET) to evaluate the properties of the sorbent. The poly (TBAB-2AA DES) was applied as a selective sorbent for preconcentration of lead from food and water samples prior to its quantification by flame atomic absorption spectroscopy (FAAS). Variable factors affecting the extraction were optimized, and under the optimum conditions, the calibration plot was linear in the range 5.0-250.0 μg L^-1. The relative standard deviation was (for n = 5) (RSD) < 3%. The limit of detection (LOD) and the enhancement factor were found to be 2.0 μg L^-1 and 50, respectively. Finally, the accuracy of the method was assessed by comparison of the results with those obtained by direct determination of lead using inductively coupled plasma mass spectrometry (ICP-MS) and spiked real samples. The obtained recoveries were between 92 and 106%. Graphical abstract.

Applications of deep eutectic solvents to quantitative analyses of pharmaceuticals and pesticides in various matrices: a brief review

Pharmaceuticals and pesticides are important analytes of interest in clinical, environmental, and food analyses for ensuring public health. Sample pretreatment steps are often prerequisites for the quantitative analysis of these compounds, which are generally present in low concentrations in samples with complex matrices. In compliance with the current trend towards green analytical chemistry, the replacement of conventional toxic organic solvents with ecofriendly and safe solvents has been pursued in developing sample pretreatment methods. Subsequent to several reports in 2017, deep eutectic solvents (DESs) have been increasingly applied as desirable alternative solvents in numerous types of sample pretreatment methods for the analysis of pharmaceuticals and pesticides. The present review summarizes analytical methods involving DESs as extraction solvents and as the reaction media or functional materials for preparing adsorbents to quantify pharmaceuticals and pesticides in various matrices.

Deep eutectic solvent-based magnetic colloidal gel assisted magnetic solid-phase extraction: A simple and rapid method for the determination of sex hormones in cosmetic skin care toners

A simple rapid and efficient deep eutectic solvent-based magnetic colloidal gel (DES-MCG) assisted magnetic solid-phase extraction (MSPE) method followed by high performance liquid chromatography with a diode array detector (HPLC-DAD) was established for determination of four sex hormones (including ethinylestradiol, norgestrel, megestrol acetate and medroxyprogesterone acetate) in cosmetic skin care toners. The DES-MCG with the desirable advantages of high adsorbing ability was prepared by combining choline chloride/urea deep eutectic solvent and magnetic multiwalled carbon nanotubes (MMWCNTs). The synthesized DES-MCG was characterized using fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The cosmetic skin care toners were concentrated by a rotary evaporator and the obtained solutions were further purified by DES-MCG assisted magnetic solid-phase extraction. Response surface methodology (RSM) was applied for efficient optimization of the main variables in the extraction procedure. Under the optimized conditions, method detection limits and method quantitation limits were in the range of 1.2-6.6 ng mL^-1 and 4.4-26.6 ng mL^-1, respectively. The recoveries of the four sex hormones in different cosmetic skin care toners ranged from 80.1% to 118.8% and the precisions were no more than 0.35%. The developed method was successfully applied for the determination of sex hormones in cosmetic skin care toners.

Deep eutectic solvent-based dispersive liquid-liquid micro-extraction of pesticides in food samples

Deep eutectic solvents are versatile, green and new generation solvents that can be used during dispersive liquid-liquid micro-extraction techniques for pesticides. They have tunable physico-chemical properties that can be easily changed by varying the ratios of hydrogen bond donors and hydrogen bond acceptors in their structures. Deep eutectic solvents are non-flammable, chemically and thermally stable solvents with low vapour pressure. Thus, they have characteristics that are similar to those of ionic liquids. However, they have simpler synthetic procedures, less expensive and are more biodegradable than ionic liquids. One of the limitations of deep eutectic solvents is their toxicity to the environment but they are less toxic than ionic liquids. This paper gives a focused and comprehensive recent review on the applications of deep eutectic solvents during dispersive liquid-liquid micro-extraction of pesticides in food samples for the period starting from 2016 to 2020. Emphasis was placed on the modifications done to the deep eutectic solvent-based dispersive liquid-liquid micro-extraction techniques in order to enhance their greenness during pesticide pre-concentration in food samples. In addition, hyphenated dispersive liquid-liquid micro-extraction techniques were also reviewed and lastly, the paper outlined the challenges associated with the use of DESs during the DLLME techniques.

Efficient extraction and determination of prenylflavonol glycosides in Epimedium pubescens Maxim. using deep eutectic solvents

INTRODUCTION

The Epimedium herb, Yinyanghuo in Chinese, is a famous Chinese herbal medicine. In this study, an efficient extraction method was developed for the extraction of major bioactive constituent epimedin A, epimedin B, epimedin C and icariin from E. pubescens Maxim. using deep eutectic solvents (DESs).

METHODOLOGY

A series of choline chloride-based DESs were synthesised for the extraction of four target compounds. DES composed of lactic acid and choline chloride with the ratio of 2:1 was selected as the most promising. Three vital factors affecting the extraction yields including water content, volume of DES aqueous solution and extraction time were optimised systematically by Box-Behnken experimental design in combination with response surface methodology. A high-performance liquid chromatography ultraviolet (HPLC-UV) method was developed for the sensitive and accurate quantification.

RESULTS

The optimal extraction conditions were obtained as follows: water content of 17.5% (v/v), volume of DES aqueous solution 3.14 ml, and extraction time of 21 min. Under the optimal extraction conditions, the developed DES method could supply almost the same extraction yield as 50% ethanol, which were 98%, 99%, 97%, 96% for epimedin A, epimedin B, epimedin C and icariin, respectively.

CONCLUSION

The present study exhibited high efficiency in extraction of prenylflavonol glycosides in E. pubescens Maxim. Thus, DESs could be used as an alternative for efficient extraction and quantification of biologically active components from natural medical plants.