Air assisted emulsification liquid-liquid microextraction based on deep eutectic solvent for preconcentration of methadone in water and biological samples

Deep Eutectic Solvents for Extraction and Preconcentration of Organic and Inorganic Species in Water and Food Samples: A Review

Deep eutectic solvents (DESs) have been developed as green solvents and these are capable as alternatives to conventional solvents used for the extraction of organic and inorganic species from food and water samples. The continuous generation of contaminated waste and increasing concern for the human health and environment have compelled the scientific community to investigate more ecological schemes. In this concern, the use of DESs have developed in one of the chief approach in the field of chemistry. These solvents have appeared as a capable substitute to conventional hazardous solvents and ionic liquids. The DESs has distinctive properties, easy preparation and components availability. It is not only used in scienctific fields but also used in quotidian life. There are many advantages of DESs in analytical chemistry, they are largely used for extraction and determination of inorganic and organic compounds from different samples. In previous a few years, several advanced researches have been focused on the separation and preconcentration of low level of pollutants using DESs as the extractants. This review summarizes the use of DESs in the separation and preconcentration of organic and inorganic species from water and food samples using various microextraction processes.

Deep Eutectic Solvents-Based Ultrasonic-Assisted Dispersive Liquid-Liquid Microextraction for the Determination of Organophosphorus Pesticides in Honeysuckle Dew Samples

A deep eutectic solvent (DES) with the ability to change from hydrophilic to hydrophobic was designed and synthesized and applied to the determination of organophosphorus (OPP) pesticides in honeysuckle dew samples. Choline chloride, phenol, and tetrahydrofuran (THF) were used as the hydrogen bond acceptor, hydrogen bond donor, and demulsifier, respectively. Eight OPP pesticides were extracted by DES coupled with ultrasonic-assisted extraction (UA) and then chromatographed by GC-MS. DES used as an extract solvent has the advantages of high extraction efficiency, low cost, and environmental protection. Furthermore, DES is compatible with GC-MS. The single factor experiment design and Box-Behnken design (BBD) were applied to the optimization of experimental factors, including the type and composition of extraction solvent, type of demulsifier solvent, the volume of DES and THF, pH of sample solution, and ultrasonic time. Under the optimum experimental conditions, the high degree of linearity from 0.1 to 20.0 ng mL-1 (R2 ≥ 0.9989), the limits of detection from 0.014 to 0.051 ng mL-1 (S/N = 3), and the recoveries of analytes from 81.4 to 104.4% with relative standard deviation below 8.6%. In addition, the adsorption mechanism of OPPs on DES was explored by adsorption kinetic studies. These results have demonstrated that the present method has offered an effective, accurate, and sensitive methodology for OPP pesticides in honeysuckle dew samples, and this method provides a reference for the detection of pesticide residues in traditional Chinese medicine.

High-throughput semi-automated emulsive liquid-liquid microextraction for detecting SDHI fungicides in water, juice, and alcoholic beverage samples via UHPLC-MS/MS

Herein, a High-Throughput Semi-automated Emulsive Liquid-Liquid Microextraction (HTSA-ELLME) method was developed to detect Succinate Dehydrogenase Inhibitor (SDHI) fungicides in food samples via UHPLC-MS/MS. The Oil-in-Water (O/W) emulsion comprising a hydrophobic extractant and water was dilutable with the aqueous sample solution. Upon injecting the primary emulsion into the sample solution, a secondary O/W emulsion was formed, allowing SDHI fungicides to be extracted. Subsequently, a NaCl-saturated solution was injected in the secondary O/W emulsion as a demulsifier to rapidly separate the extractant, eliminating the need for centrifugation. A 12-channel electronic micropipette was used to achieve a high-throughput semi-automation of the novel sample pretreatment. The linear range was 0.003-0.3 μg L-1 with R2 > 0.998. The limit of detection was 0.001 μg L-1. The HTSA-ELLME method successfully detected SDHI fungicides in water, juice, and alcoholic beverage samples, with recoveries and relative standard deviations of 82.6-106.9% and 0.8-5.8%, respectively. Unlike previously reported liquid-liquid microextraction approaches, the HTSA-ELLME method is the first to be both high-throughput and semi-automated and may aid in designing pesticide pretreatment processes in food samples.

Deep eutectic solvents for the extraction of polyphenols from food plants

Deep Eutectic Solvents (DESs) offer a promising, sustainable alternative for extracting polyphenols from food plants, known for their health benefits. Traditional extraction methods are often costly and involve toxic solvents. This review discusses the basic concepts, preparation techniques, and factors influencing the effective and safe use of DESs in polyphenol extraction. DESs' adaptability allows integration with other green extraction technologies, such as microwave- and ultrasound-assisted extractions, enhancing their efficiency. This adaptability demonstrates the potential of DESs in the sustainable extraction of bioactive compounds. Current research indicates that DESs could play a significant role in the sustainable procurement of these compounds, marking an important advancement in food science research and development. The review underscores DESs as a realistic, eco-friendly alternative in the realm of natural extraction technologies, offering a significant contribution to sustainable practices in food science.

Eco-Friendly and Efficient Extraction of Polysaccharides from Acanthopanax senticosus by Ultrasound-Assisted Deep Eutectic Solvent

A green extraction method was developed using deep eutectic solvent extraction for the polysaccharide from Acanthopanax senticosus (A. senticosus). Among the eight types of DES prepared, the DES with a ratio of 1:4 L-malic acid to L-proline was found to be a suitable extraction solvent based on the extraction efficiency. The extraction parameters were optimized by Plackett-Burman and response surface methodology (RSM). The best extraction conditions were found for L-malic acid. Under the conditions of an L-malic acid/L-proline ratio of 1:4, ultrasonic power of 240 W, material-liquid ratio of 31.068 g/mL, water content of 32.364%, extraction time of 129.119 min, and extraction temperature of 60 °C, the extraction rate of A. senticosus polysaccharides was 35.452 ± 0.388 mg-g-1. This rate was higher than that of polysaccharides obtained by hot water extraction (13.652 ± 0.09 mg-g-1). The experimental results were best fitted by the quasi-secondary kinetic model when compared to two other kinetic models. Electron microscopic observations showed that DESs were more destructive to plant cells. The polysaccharide extracted from DESs had more monosaccharide components, a lower molecular weight, a higher antioxidant capacity, and superior anti-glycation activity compared to polysaccharides extracted from water (ASPS-PW). This study demonstrates the effectiveness of DESs in obtaining polysaccharides from A. senticosus.

Highly efficient determination of metal ion in cosmetic samples by reversed-phase liquid-liquid microextraction based on green hydrophobic deep eutectic solvent

In this paper, a green hydrophobic deep eutectic solvent (HDES) composed of menthol and hexanoic acid was employed to dissolve cosmetics containing Cd2+ and Cd2+ was extracted using an EDTA-2Na saturated solution, analyzed by FAAS. The study found that HDES-1 can be recycled and reused well; the stability constants of Cd2+ EDTA chelates play an important role in the extracting process; the optimum conditions were: the solubility of HDES-1 was 20 mL/g for cosmetic sample at an indoor temperature of around 10 °C; the dissolver-extractant ratio was 2:1; the LOD was 0.037 mg/kg; the RSD was 3.5%; and the recovery was 85.5-118.3%. The developed method was successfully applied to actual cosmetic samples with satisfactory results, and it was also applied for the determination of Mg2+, Mn2+, and Cu2+ in cosmetic samples.

Development of magnetic dispersive micro-solid phase extraction of four phenolic compounds from food samples based on magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent

A magnetic dispersive micro-solid phase extraction technique (CS@Fe₃O₄-MD-μSPE-DESP) based on magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent was developed and applied to determinations of four phenolic compounds in food samples. To prevent environmental pollution and the introduction of toxic substances, deep eutectic supramolecular solvents (DESPs), which exhibited greater desorption capacities than conventional organic solvents and deep eutectic solvents, were used as novel green eluents for the first time. Some important parameters were screened by the Plackett-Burman method and then further optimized with response surface methodology (RSM). Under the optimal conditions, the proposed method showed excellent methodological indices with linearity over the range 0.1-200.0 µg·mL^-1, R² > 0.9988, extraction recoveries above 94.8 %, and precision (RSD%) below 2.9 %. The established method finishes the process of adsorption and desorption in approximately 3 min and enhances the efficiency for determination of phenolic compounds.

Application of Recently used Green Solvents in Sample Preparation Techniques: A Comprehensive Review of Existing Trends, Challenges, and Future Opportunities

Green solvents (GSs) has gained significant attention in recent years due to their potential as safer and more sustainable alternatives to traditional organic solvents. Solvents are used in a wide range of applications, from industrial processes to everyday products. Solvent emissions and losses can have a significant impact on the environment and human health, which is why many initiatives are being undertaken to get rid of or switch to eco-friendly alternatives. A key area of green chemistry that led to the concept of "green" solvents is the development of alternative solvents that are less toxic and more environmentally friendly than traditional organic solvents. The advantages of using green solvents over conventional ones are their environmental friendliness, biocompatibility, biodegradability, and simplicity of preparation. Different sample preparation techniques have successfully utilized green solvents to offer a sustainable separation media for the extraction of a variety of inorganic and organic compounds which are crucial for research in environmental samples. Recent developments in green analytical chemistry (GAC) have focused on how to prepare and use samples using environmentally sustainable solvents. The current study covers the advance and currently used green solvents with an emphasis on environmentally friendly sample preparation methods. This review aims to briefly summarize the current state of knowledge about the use of green solvents particularly ionic liquids, deep eutectic solvents and switchable solvents (SSs) with the perspective of GAC in sample preparation methods.

Natural Deep Eutectic Solvent-Based Dispersive Liquid-Liquid Microextraction Coupled with Direct Analysis in Real Time Mass Spectrometry: A Green Temperature-Mediated Analytical Strategy

Green analytical chemistry (GAC) represents a rapidly growing research field that aims at developing novel analytical approaches with minimal consumption of hazardous reagents and solvents. The current study reports on a GAC methodology exploiting the unique physicochemical properties of natural deep eutectic solvents (NADESs), a supposedly environmentally friendly class of solvents. Based on a temperature-mediated strategy, the NADESs were manipulated to undergo multiple phase transitions for favorable functionality and performance. As proof-of-concept demonstrations, both hydrophobic and hydrophilic NADESs were prepared for the extraction and analysis of eight phthalate esters in aqueous samples (food simulants) and three aflatoxins in oily samples (edible oils), respectively. NADES-based dispersive liquid-liquid microextraction (DLLME) was employed to achieve high-efficiency sample pretreatment. Afterward, the NADESs were transformed from liquids into solids by tuning the peripheral temperature for a convenient phase separation from the sample matrices. The solidified NADES extracts were melted and vaporized at elevated temperatures by transmission-mode direct analysis in real time (DART) for further quadrupole-Orbitrap high-resolution mass spectrometry (Q-Orbitrap HRMS) analysis. The developed protocol was validated, achieving good repeatability with relative standard deviations (RSDs) of less than 9% and satisfactory sensitivity with limits of detection (LODs) and quantitation (LOQs) ranging from 0.1 to 0.8 and 0.2 to 2.0 μg/kg, respectively. The greenness of the analytical methodology was assessed with the calculated scores of 0.66 and 0.57 for the hydrophobic and hydrophilic NADES-based protocols, respectively. The method was applied to marketed samples, highlighting the great potential for green chemical analysis.

Recent modified air-assisted liquid–liquid microextraction applications for medicines and organic compounds in various samples: A review

Air-assisted liquid–liquid microextraction (AALLME) is a procedure for sample preparation that has high recoveries and high preconcentration factors while using a small amount of extractants. This procedure has gained widespread acceptance among scientists due to a variety of advantages, including its easiness, being cheap, green, and available in most laboratories. The current review has focused on the analysis of medicines and organic compounds using various modes of AALLME. The use of various extractants and support factors were developed in many modes of AALLME. A review of literature revealed that the procedure is used as a powerful and efficient approach for extracting medicals and organic compounds. This review explained 12 different types of AALLME methods. The findings on the modifications of AALLME modes that have been published are summarized. Future directions are also being discussed.

Deep eutectic solvents as switchable solvents for highly efficient liquid-liquid microextraction of phenolic antioxidant: Easily tracking the original TBHQ in edible oils

Synthetic antioxidant tert-butylhydroquinone (TBHQ) is easily oxidized to tert-butylquinone (TQ) during the storage of edible oils, resulting in an obvious decrease in the content of TBHQ in edible oils. Therefore, it is quite desirable to develop a simple analytical method for accurately tracking the original content of TBHQ in edible oils. In this work, deep eutectic solvents (DESs) have been successfully used in room temperature vortex-assisted liquid-liquid microextraction (VALLME) of TBHQ from edible oils. The DES composed of ethylene glycol and choline chloride (ChCl) could selectively extract TBHQ from edible oils containing both TBHQ and TQ. The DES composed of sesamol and ChCl (molar ratio of 3:1) could efficiently reduce TQ to TBHQ and extract TBHQ from edible oils. The whole VALLME process only required 5 min at room temperature. This switchable DESs-based VALLME with common RP-HPLC analysis showed high efficiency and good performance with linearity (R² = 0.9999) in 5-500 mg/kg range, detection limit of 0.02 mg/kg, recoveries of 96.1-106.0% and intra-/inter-day precision below 2.0%. This analytical method is suitable for detecting the current content of TBHQ and tracking the original content of TBHQ during the storage of edible oils at room temperature, respectively.

Enhancing the electrochemical sensitivity of hydroquinone using a hydrophobic deep eutectic solvent-based carbon paste electrode

The present study reports the synthesis and characterization of hydrophobic deep eutectic solvents (HDES) based on fatty acids and tetrabutylammonium bromide (TBAB) or 1-octanol using Fourier transform infrared spectroscopy, and the analysis of the physicochemical properties (viscosity, density, electrical conductivity, and water content) of these solvents. A carbon paste electrode modified with 6.0% (m/m) decanoic acid and TBAB-based HDES was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. The oxidation peak currents of the proposed electrode were enhanced by its high electrochemical activity, fast electron transfer rate, and high surface area, while a remarkable decrease was observed in the peak potential separation. The electrochemical determination of hydroquinone (H₂Q) was carried out using square-wave adsorptive anodic stripping voltammetry (SWAdASV). The electrode response was found to be linear in the H₂Q concentration range of 2.5 × 10^-6-3.0 × 10^-3 mol L^-1, with the limit of detection (LOD) of 7.7 × 10^-7 mol L^-1. The method was successfully applied for H₂Q determination in dermatological creams.

Progress in pretreatment of methadone: an update since 2015

Methadone, a µ-opioid receptor agonist, is widely used in pain-relieving and treating opioid dependence. If not strictly controlled, as an opioid substitute, it can lead to abuse and cause more severe withdrawal responses than heroin. Also, overdose or abuse of this drug in clinical use may provide severe side effects such as apnea, circulatory collapse, cardiac arrest, and even death. For these reasons, simple, rapid, and efficient methods have been developed for the pretreatment of methadone. This review presents a comprehensive conclusion of the pretreatment methods used for methadone in various sample matrices, focusing on the developments since 2015. Traditionally used pretreatment methods like solid-phase extraction and liquid-liquid extraction are discussed and newly developed methods like solid-phase microextraction and liquid-liquid microextraction along with new materials applied are focused.

A Green Method of Extracting and Recovering Flavonoids from Acanthopanax senticosus Using Deep Eutectic Solvents

In recent years, green extraction of bioactive compounds from herbal medicines has generated widespread interest. Deep eutectic solvents (DES) have widely replaced traditional organic solvents in the extraction process. In this study, the efficiencies of eight DESs in extracting flavonoids from Acanthopanax senticosus (AS) were compared. Response surface methodology (RSM) was employed to optimize the independent variable including ultrasonic power, water content, solid-liquid ratio, extraction temperature, and extraction time. DES composed of glycerol and levulinic acid (1:1) was chosen as the most suitable extraction medium. Optimal conditions were ultrasonic power of 500 W, water content of 28%, solid-liquid ratio of 1:18 g·mL⁻¹, extraction temperature of 55 °C, and extraction time of 73 min. The extraction yield of total flavonoids reached 23.928 ± 0.071 mg·g⁻¹, which was 40.7% higher compared with ultrasonic-assisted ethanol extraction. Macroporous resin (D-101, HPD-600, S-8 and AB-8) was used to recover flavonoids from extracts. The AB-8 resin showed higher adsorption/desorption performance, with a recovery rate of total flavonoids of up to 71.56 ± 0.256%. In addition, DES solvent could efficiently be reused twice. In summary, ultrasonic-assisted DES combined with the macroporous resin enrichment method is exceptionally effective in recovering flavonoids from AS, and provides a promising environmentally friendly and recyclable strategy for flavonoid extraction from natural plant sources.

Development of effervescence-assisted switchable-polarity solvent homogeneous liquid-phase microextraction for the determination of permethrin and deltamethrin in water samples prior to GC-FID

An effervescent tablet-assisted switchable polarity solvent-based homogeneous liquid-phase microextraction (ETA-SPS-HLPME) combined with gas chromatography with flame ionization detection has been conducted for the separation, preconcentration, and detection of permethrin and deltamethrin in the river water specimens. The triethylamine (TEA) was utilized as a switchable polarity solvent in this method. The switching process was carried out by the dissolution of an effervescent tablet including an effervescency agent (sodium carbonate) and a proton donor agent (citric acid). Changing the pH of the specimen solution enhanced the conversion of TEA into protonated triethylamine carbonate (P-TEA-C) through the tablet that generated carbon dioxide (CO₂ ) bubbles in situ. Finally, the addition of sodium hydroxide changed the ionization state of TEA and separated two phases. Influential factors in extraction were investigated. According to optimal situations, the limits of detection (LOD) and the limits of quantification (LOQ) were obtained 0.16 and 0.5 μgL^-1 for permethrin and 0.03 and 0.1 μgL^-1 for deltamethrin respectively. The preconcentration factor (PF) was achieved 194 in river water samples and interday and intraday precision (RSD % n = 5) was <5%. The extraction recovery was obtained in the range of 93.0-97% for permethrin and deltamethrin in water samples.

Application of Extraction and Determination Based on Deep Eutectic Solvents in Different Types of Environmental Samples

Water sources are an indispensable resource for human survival. Monitoring the pollution status of the surrounding environment is necessary to protect water sources. Research on the environmental matrix of deep eutectic solvents (DESs) has expanded rapidly because of their high extraction efficiency for various target analytes, controllable synthesis, and versatile structure. Following the synthesis of hydrophobic deep eutectic solvents (HDESs), their application in aqueous matrices broadened greatly. The present review conducted a survey on the pollutant extraction methods based DESs in environmental matrices from two aspects, application methods and matrix types; discussed the potential risk of DESs to the environment and future development trends; and provided some references for researchers to choose DES-based extraction methods for environmental research.

Fabrication and characterization of magnetic molecularly imprinted polymer based on deep eutectic solvent for specific recognition and quantification of vanillin in infant complementary food

A magnetic molecularly imprinted polymer based on deep eutectic solvent was synthesized for specific identification and quantification of vanillin. Fe₃O₄@SiO₂-CC and deep eutectic solvent were applied as the carrier of magnetic material and functional monomer, respectively. According to composition and morphology characterizations and adsorption kinetics, the imprinted polymer had excellent advantages on adsorption capacity and identification specificity for vanillin compared with non-imprinted polymer, while its reusability still remained stable. According to the high-performance liquid chromatography, the detection method based on imprinted polymer produced satisfactory analytical results. The limit of quantification was 0.2 μg·mL^-1. The mean spiked recoveries for vanillin ranged from 91.2% to 100.2% with intra- and inter-day precision were both less than 7.2%. Compared to traditional extraction methods, this method presented best adsorption and extraction performances. In summary, the method could be further applied to the specific separation and quantification of vanillin in infant complementary food.

Vortex-assisted dispersive liquid-phase microextraction for the analysis of main active compounds from Zi-Cao-Cheng-Qi decoction based on a hydrophobic deep eutectic solvent

In this study, a vortex-assisted hydrophobic deep eutectic solvent dispersive liquid-phase microextraction was developed and used for the extraction and preconcentration of six main active compounds in Zi-Cao-Cheng-Qi decoction. The deep eutectic solvent, prepared by mixing tetrabutylammonium chloride and hexanoic acid at a molar ratio of 1:1, was added to the sample solution containing the analytes. In the absence of disperser, the extractant was rapidly dispersed into fine droplets by the aid of vortex and adequately contacted with the analytes. Some key parameters affecting the approach including extraction solvent type and volume, sample phase pH, extraction time, centrifugation time, and salt concentration were investigated and optimized. Under the optimum conditions, enrichment factors of the target analytes were in the range of 3-330. The calibration graphs were linear with a correlation coefficient (r) ≥ 0.9929. The detection limits were 0.3-0.9 ng/mL, and the satisfactory precisions (relative standard deviations, 0.5-8.9%) and accuracies (relative recoveries, 91.1-102.2%) were also obtained. The developed method was rapid (only 2 min), eco-friendly, effective, and easy to operate. And it has been successfully applied to simultaneous extraction, enrichment, and determination of the main active compounds in a traditional Chinese medicinal formula coupled with high-performance liquid chromatography.

Review of LC techniques for determination of methadone and its metabolite in the biological samples

Methadone (MTD) is a synthetic analgesic drug used for treating opioid dependence and effectively used clinically for patients with severe pain. The abuse of MTD may lead to poisoning, disorder in the central nervous system and even death. The regular monitoring of MTD in biological matrices including serum, plasma and urine samples is an effective way to control abuse of MTD. In this manner, the selection of analytical monitoring of MTD in biological matrices is of paramount importance. This study was conducted to review high-performance liquid chromatography (HPLC) techniques carried out on MTD and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in the biological samples during 2015-June 2021.

Application of Microextraction-Based Techniques for Screening-Controlled Drugs in Forensic Context-A Review

The analysis of controlled drugs in forensic matrices, i.e., urine, blood, plasma, saliva, and hair, is one of the current hot topics in the clinical and toxicological context. The use of microextraction-based approaches has gained considerable notoriety, mainly due to the great simplicity, cost-benefit, and environmental sustainability. For this reason, the application of these innovative techniques has become more relevant than ever in programs for monitoring priority substances such as the main illicit drugs, e.g., opioids, stimulants, cannabinoids, hallucinogens, dissociative drugs, and related compounds. The present contribution aims to make a comprehensive review on the state-of-the art advantages and future trends on the application of microextraction-based techniques for screening-controlled drugs in the forensic context.

Sustainable green solvents for microextraction techniques: Recent developments and applications

The development and application of alternative green solvents in analytical techniques consist of trends in sample preparation, since this subject represents an important step toward sustainability in experimental procedures. This review is focused on the main theoretical aspects related to deep eutectic solvents (DES), switchable hydrophilicity solvents (SHS) and supramolecular solvents (SUPRAS). Recent applications are highlighted, particularly for the extraction of different analytes from environmental, biological and food matrices. Moreover, novel configurations are emphasized, aiming for efficient, automated and high-throughput procedures. This review also provides some critical points regarding the use of these solvents and their green aspects.

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%.

A miniaturized spray-assisted fine-droplet-formation-based liquid-phase microextraction method for the simultaneous determination of fenpiclonil, nitrofen and fenoxaprop-ethyl as pesticides in soil samples

RATIONALE

Pesticides are a group of micropollutants that persist for a long time in the environment and pose threats to life. Much effort has been devoted to developing pre-concentration methods capable of producing samples suitable for the detection of pesticides. However, better methods are still required to detect these compounds when they are present in trace concentrations in soils.

METHOD

Spray-assisted fine-droplet-formation-based liquid-phase microextraction was used to prepare soil samples containing three different pesticides, fenpiclonil, nitrofen and fenoxaprop-ethyl, for subsequent analysis by gas chromatography/mass spectrometry (GC/MS). A spraying apparatus was used for the dispersion of the extraction solvent into the sample/standard solution to improve the extraction efficiency. Optimization studies were performed to lower the detection limits of these analytes and the results obtained by the application of the newly developed system were compared with those obtained using the conventional GC/MS method.

RESULTS

A calibration curve over the range 5.0-100 μg L^-1 was obtained under the optimal conditions. The limits of detection and quantification were 1.56-1.80 μg L^-1 and 5.21-5.98 μg L^-1 , respectively. The enhancements in detection ability over the conventional method for the three tested pesticides were 188.01, 176.96 and 517.14 for fenpiclonil, nitrofen and fenoxaprop-ethyl, respectively Recovery studies performed in soil samples were satisfactory reflecting accurate applicability of the developed method.

CONCLUSIONS

The developed microextraction method is a time-saving and simple version of the traditional dispersive liquid-liquid microextraction method that also reduces the use of dispersive solvents.

Deep eutectic solvent-based ultrasound-assisted emulsification microextraction for the rapid determination of benzotriazole and benzothiazole derivatives in surface water samples

This work describes a simple and environmental-friendly method for the simultaneous determination of five benzotriazole derivatives (BTRs) and four benzothiazole derivatives (BTs) that are frequently found in surface water. The target analytes were efficiently extracted from water samples using a "green" deep eutectic solvent (DES) as the extraction solvent based- ultrasound-assisted emulsification microextraction (DES-USAEME), and their determination were performed by ultrahigh-performance liquid chromatography and electrospray ionization (+)-quadrupole time-of-flight mass spectrometry (UHPLC-ESI(+)-QToF-MS). The DES was composed of a mixture of choline chloride and phenol (molar ratio 1:2). The DES-USAEME factors were optimized by a Box-Behnken Design coupled response surface methodology. The developed method was validated, providing limits of quantitation (LOQs; 02 μg L^-1), high precisions (1-8%), and satisfactory mean spiked recoveries (72-104 %). Relatively high total concentrations of the target analytes were found in samples collected from a reservoir (47.2-101.3 μg L^-1), which may have been released from tire-wear particles and scrap tires from buses and old tires that were strung alongside the shuttle boats to prevent the boats from coming into contact with each other or from impacting against the dock during docking. This is the first study on the occurrence of BTRs and BTs in reservoir samples.

A Review of the Use of Eutectic Solvents, Terpenes and Terpenoids in Liquid–liquid Extraction Processes

Diverse and abundant applications of the eutectic solvents have appeared in the last years. Their promising tunable properties, eco-friendly character and the possibility of being prepared from numerous compounds have led to the publication of numerous papers addressing their use in different areas. Terpenes and terpenoids have been employed in the formulation of eutectic solvents, though they also have been applied as solvents in extraction processes. For their hydrophobic nature, renewable character, low environmental impact, cost and being non-hazardous, they have also been proposed as possible substitutes of conventional solvents in the separation of organic compounds from aqueous streams, similarly to hydrophobic eutectic solvents. The present work reviews the application of eutectic solvents in liquid–liquid extraction and terpenes and terpenoids in extraction processes. It has been made a research in the current state-of-the-art in these fields, describing the proposed applications of the solvents. It has been highlighted the scale-up feasibility, solvent regeneration and reuse procedures and the comparison of the performance of eutectic solvents, terpenes and terpenoids in extraction with conventional organic solvents or ionic liquids. Ultimately, it has been also discussed the employ of predictive methods in extraction, the reliability of thermodynamic models in correlation of liquid–liquid equilibria and simulation of liquid–liquid extraction processes.

Extraction of Flavonoids from Scutellariae Radix using Ultrasound-Assisted Deep Eutectic Solvents and Evaluation of Their Anti-Inflammatory Activities

Deep eutectic solvents (DESs) play important roles in the extraction of active constituents in traditional Chinese medicine. Ultrasound-assisted DES has been used to extract flavonoids from Scutellaria baicalensis. Using the contents of scutellarin, baicalin, baicalein, wogonoside, wogonin, and oroxylin A as quantitative indices, different kinds of DESs have been optimized for extraction and betaine/acetic acid has shown the highest yield. The Box-Behnken response surface method (RSM) was utilized to select the extraction conditions with the highest yields. The optimal extraction conditions were as follows: the molar ratio of betaine/acetic acid was 1:4, the water content was 40%, the solid/liquid ratio was 1:100 g/mL, the extraction temperature was 52 °C, and the extraction time was 23 min. Compared with traditional reflux extraction using 70% ethanol as the solvent, ultrasound-assisted DES has a shorter extraction time and higher yields. Furthermore, anti-inflammatory activities of the two extracts by ultrasound-assisted DES and reflux were compared using RAW264.7 cells and the methyl thiazolyl tetrazolium (MTT) method, and they showed equal anti-inflammatory activities. The results demonstrated that the ultrasound-assisted DES method for extraction of flavonoids from scutellariae radix is simple, green, efficient, and reproducible. This research provides good method guides for the rapid and efficient extraction of flavonoids from natural sources.

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.