Ultrasound-assisted dispersive liquid-phase microextraction by solidifying L-menthol-decanoic acid hydrophobic deep eutectic solvents for detection of five fungicides in fruit juices and tea drinks

Investigating a new approach for magnetic ionic liquids: Dispersive liquid-liquid microextraction coupled to pyrolysis gas-chromatography-mass spectrometry to determine flame retardants in sewage sludge samples

This study addresses the analysis of emerging contaminants, often using chromatographic techniques coupled to mass spectrometry. However, sample preparation is often required prior to instrumental analysis, and dispersive liquid-liquid microextraction (DLLME) is a viable strategy in this context. DLLME stands out for its ability to reduce sample and solvent volumes. Notably, dispersive liquid-liquid microextraction using magnetic ionic liquids (MILs) has gained relevance due to the incorporation of paramagnetic components in the chemical structure, thereby eliminating the centrifugation step. A pyrolizer was selected in this work to introduce sample onto the GC column, since the MIL is extremely viscous and incompatible with direct introduction through an autosampler. This study is the first to report the use of a DLLME/MIL technique for sample introduction through a pyrolizer in gas chromatography coupled to mass spectrometry (GC-MS). This approach enables the MIL to be compatible with gas chromatography systems, resulting in optimized analytical and instrument performance. The analysis of polybrominated diphenyl ether flame retardants (PBDEs) was focused on the PBDE congeners 28, 47, 99, 100, and 153 in sewage sludge samples. The [P6,6,6,14+]2[MnCl42-] MIL was thoroughly characterized using UV-Vis, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy, as well as thermal analysis. In the chromatographic method, a pyrolyzer was used in the sample introduction step (Py-GC-MS), and critical injection settings were optimized using multivariate approaches. Optimized conditions were achieved with a temperature of 220 °C, a pyrolysis time of 0.60 min, and an injection volume of 9.00 μL. DLLME optimization was performed through central compound planning (CCD), and optimized training conditions were achieved with 10.0 mg of MIL, 3.00 μL of acetonitrile (ACN) as dispersive solvent, extraction time of 60 s, and volume of a sample of 8.50 mL. Precision was observed to range from 0.11 % to 12.5 %, with limits of detection (LOD) of 44.4 μg L-1 for PBDE 28, 16.9 μg L-1 for PBDE 47 and PBDE 99, 33.0 μg L-1 for PBDE 100 and 375 μg L-1 for PBDE 153. PBDE 28 was identified and analyzed in the sludge sample at a concentration of 800 μg L-1. The use of MIL in dispersive liquid-liquid microextraction combined with pyrolysis gas chromatography-mass spectrometry enables identification and quantification of PBDEs in sewage sludge samples at concentrations down to the µg L-1 level.

A Novel DLLME Method Involving a Solidifying Hydrophobic Deep Eutectic Solvent Using Hydrophilic Deep Eutectic Solvent as the Dispersant for the Determination of Polychlorinated Biphenyls in Water Samples

This paper presents a novel dispersive liquid-liquid microextraction (DLLME) method that employs solidified hydrophobic deep eutectic solvent (DES) with hydrophilic DES acting as the dispersant. The aim is to enrich polychlorinated biphenyls (PCBs) from water samples for subsequent determination by gas chromatography-mass spectrometry. The effects of both the hydrophobic DES as the extractant and the hydrophilic DES as the dispersant were thoroughly investigated. Optimization of the key factors influencing extraction efficiency was performed, and the method was subsequently validated. Specifically, a hydrophobic DES called DES2, prepared by combining thymol and decanoic acid in a molar ratio of 3:2, was selected as the extraction solvent. Meanwhile, a hydrophilic DES named DES6, prepared from choline chloride and acetic acid in a molar ratio of 1:2, was chosen as a dispersant. Under the optimal extraction conditions, the developed method exhibited excellent linearity over the concentration range of 0.01-5.0 µg/L, low limits of detection ranging from 3.0 to 5.1 ng/L, relative standard deviations less than 4.1%, and enrichment factors between 182 and 204 for PCBs. Finally, the effectiveness of the developed method was successfully demonstrated through residue determination of PCBs in water samples.

Menthol-Based (Deep) Eutectic Solvents: A Review on Properties and Application in Extraction

In the last 10 years the interest in deep eutectic solvents (DESs) as a new class of green solvents has considerably increased. The emergence of numerous of hydrophobic DESs has stimulated intensive research into their application in extraction technologies, including sample preparation. As the properties of such systems are highly dependent on the properties of their components (hydrogen bond donors and acceptors) and can be finely tuned, DESs can be successfully used for the extraction of both metal ions and organic substances, including biomolecules. Despite the rapidly increasing number of publications on the use of DESs as an extraction medium, including review articles, information on the extraction properties of DESs in terms of their chemical composition has not yet been summarized. This review covers available literature data on the physicochemical properties of menthol-based eutectic solvents and the results of their practical application as an extraction medium. Also, the appropriateness of using the term "DES" for all mixtures with melting points lower than the melting points of their components is discussed.

Deep eutectic solvents in sample preparation and determination methods of pesticides: Recent advances and future prospects

This review summarizes recent advances of deep eutectic solvents (DESs) in sample preparation and determination methods of pesticides in food, environmental, and biological matrices since 2019. Emphasis is placed on new DES categories and emerging microextraction techniques. The former incorporate hydrophobic deep eutectic solvents, magnetic deep eutectic solvents, and responsive switchable deep eutectic solvents, while the latter mainly include dispersive liquid-liquid microextraction, liquid-liquid microextraction based on in-situ formation/decomposition of DESs, single drop microextraction, hollow fiber-liquid phase microextraction, and solid-phase microextraction. The principles, applications, advantages, and limitations of these microextraction techniques are presented. Besides, the use of DESs in chromatographic separation, electrochemical biosensors, fluorescent sensors, and surface-enhanced Raman spectroscopy are discussed. This review is expected to provide a valuable reference for extracting and detecting pesticides or other hazardous contaminants in the future.

Analytical studies on some pesticides with antifungal effects: Simultaneous determination by HPLC, investigation of interactions with DNA and DNA damages

A simple, and fast method was developed for the simultaneous determination of five fungicides, namely thiram (THR), epoxiconazole (EPO), hexaconazole (HEX), tebuconazole (TEB), and diethofencarb (DIE), in different matrices by HPLC-UV. Parameters influencing the peak shape and resolution, such as the composition of mobile phase, pH and concentration of buffer solution, and column temperature, were examined and optimized. The proposed method was validated in terms of linearity, sensitivity, precision, and accuracy. Forced degradation studies were carried out for all analytes to demonstrate the specificity of the method and to evaluate the stability of analytes under different conditions. DNA interaction and DNA damage studies were conducted by HPLC and comet assay, respectively. All fungicides were found to bind DNA, except for DIE. While the binding coefficients for EPO, HEX, and TEB were of the order of 104, THR was found to interact more strongly with DNA with a binding coefficient of higher than 106. DIE did not induce DNA damage at any concentration tested. On the other hand, TEB, HEX, and EPO induced DNA damage up to 30 µg/mL. THR showed cytotoxic effects at 20 and 30 µg/mL and caused significant DNA damage at lower concentrations.

Applications of Deep Eutectic Solvents in Sample Preparation and Extraction of Organic Molecules

The use of deep eutectic solvents (DES) is on the rise worldwide because of the astounding properties they offer, such as simplicity of synthesis and utilization, low-cost, and environmental friendliness, which can, without a doubt, replace conventional solvents used in heaps. In this review, the focus will be on the usage of DES in extracting a substantial variety of organic compounds from different sample matrices, which not only exhibit great results but surpass the analytical performance of conventional solvents. Moreover, the properties of the most commonly used DES will be summarized.

Ultrasound-assisted switchable hydrophilic solvent-based homogeneous liquid-liquid microextraction for the determination of triazole fungicides in environmental water by GC-MS

A new method was developed for the determination of three triazole fungicides in environmental water samples by gas chromatography-mass spectrometry (GC-MS) based on ultrasonic assisted switchable hydrophilic solvent homogeneous liquid-liquid microextraction. As a switchable hydrophilic solvent, N,N-dimethylcyclohexylamine (DMCHA) does not require a dispersant or centrifugation. Ultrasound assistance is helpful to speed up the extraction of target compounds and can reduce the pretreatment time. The entire pretreatment process of this method only takes 5 minutes. Using the Box-Behnken design as the means of optimization, optimal extraction conditions were obtained through a mathematical model. Good linearity was obtained in the range of 5-500 μg L^-1, and the correlation coefficient of target compounds was greater than 0.999. The matrix spiked recoveries were between 81.3% and 111.1% and the detection limit was between 0.46 and 0.99 μg L^-1. Intraday relative standard deviation (n = 3) was 13.0-13.9% at 100 μg L^-1. Finally, it was concluded that the method is a rapid, efficient and simple method for the analysis of triazole fungicides in water.

Deep Eutectic Solvents as Promising Green Solvents in Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet: Recent Applications, Challenges and Future Perspectives

Deep eutectic solvents (DESs) have recently attracted attention as a promising green alternative to conventional hazardous solvents by virtue of their simple preparation, low cost, and biodegradability. Even though the application of DESs in analytical chemistry is still in its early stages, the number of publications on this topic is growing. Analytical procedures applying dispersive liquid-liquid microextraction based on the solidification of floating organic droplets (DLLME-SFOD) are among the more appealing approaches where DESs have been found to be applicable. Herein, we provide a summary of the articles that are concerned with the application of DESs in the DLLME-SFOD of target analytes from diverse samples to provide up-to-date knowledge in this area. In addition, the major variables influencing enrichment efficiency and the microextraction mechanism are fully investigated and explained. Finally, the challenges and future perspectives of applying DESs in DLLME-SFOD are thoroughly discussed and are critically analyzed.

Deep Eutectic Solvents: Are They Safe?

Deep eutectic solvents (DESs) are a relatively new type of solvent that have attracted the attention of the scientific community due to their environmentally friendly properties and their versatility in many applications. Many possible DESs have been described and, thus, it is not easy to unequivocally characterize and generalize their properties. This is especially important in the case of the (eco)toxicity information that can be found for these mixtures. In this review, we collect data on the human and environmental toxicity of DESs, with the aim of gathering and exploring the behavioral patterns of DESs. The toxicity data found were analyzed attending to different factors: hydrogen bond donors or acceptors that form part of the eutectic mixture, pH, and the presence of organic acids in the DES molar ratio of the components, or interactions with natural compounds. In the case of ecotoxicity, results generally depend on the biomodel studied, along with other factors that have been also revised. Finally, we also carried out a revision of the biodegradation of DESs.