Solidification of a Switchable Solvent-Based QuEChERS Method for Detection of 16 Pesticides in Some Fruits and Vegetables

Optimizing Analysis Methods: Rapid and Accurate Determination of Cuaminosulfate Residues with LC-MS/MS Based on Box-Behnken Design Study

In view of the defects in the previous detection of cuaminosulfate, which only focused on the analysis of copper ions, there is currently no analysis method available to determine the actual state of cuaminosulfate as chelated or bound. In order to investigate the dissipation and terminal residues in soil and watermelon of cuaminosulfate for food safety and environmental risk, a highly effective technique was developed to detect cuaminosulfate residues in watermelon and soil, and field experiments were conducted in China. After single-factor experiments, residual cuaminosulfate in samples was extracted by pure water, purified using a liquid-liquid approach combined with a dispersive solid-phase extraction, and detected by liquid chromatography tandem mass spectrometry (LC-MS/MS). The Box-Behnken design (BBD) study was used to find the optimal solutions for the time of liquid-liquid purification, the amount of extraction solvent, and the amounts of cleanup sorbents for the analytical method. The average recovery of the method was in the range of 80.0% to 101.1%, the average relative standard deviation (RSD) was 5.3-9.9%, and the detection limit was lower than 0.05 mg/kg. The BBD study not only improved the extraction rate of the method, but also saved time and was operated easily. The final residues of cuaminosulfate in watermelon at different sampling intervals were all lower than 0.05 mg/kg under field conditions. The cuaminosulfate in soils dissipated following exponential kinetics, with half-life values in the range of 9.39 to 12.58 days, which varied by different locations. Based on the validated method, food safety residues and soil residues can be determined rapidly and accurately.

Switchable solvent-based micro-extraction of pesticides in food and environmental samples

Switchable solvents are new generation solvents that are environmentally friendly and can be used for the effective pre-concentration of pesticide residues in food and environmental matrices. They have physico-chemical properties that can be switched abruptly and reversibly between two opposite forms. The common switchable solvents used commonly during pesticide pre-concentration involve polarity switch. Such solvent switch between hydrophobic and hydrophilic forms during pesticide pre-concentration. Secondary and tertiary amines are typical switchable hydrophilicity solvents. The amines are hydrophobic but they abruptly and reversibly switch to their hydrophilic forms on addition of CO₂ to them. The application of amine-based switchable solvents during pre-concentration of pesticide residue in food and environmental samples are discussed in this paper. Medium-chain fatty acids can also be used as switchable solvents. Their switch between hydrophobic and hydrophilic forms is usually triggered by pH changes. Applications of fatty acid-based switchable solvents during pre-concentration of pesticide residues are reviewed in this paper. Switchable solvent-based micro-extraction can be combined with other pre-concentration techniques to enhance selectivity resulting in clean chromatograms. This paper has a section dedicated to the application of hyphenated switchable solvent-based micro-extraction techniques during pre-concentration of pesticides in food and environmental samples. In addition, the challenges associated with the use of switchable solvents during micro-extraction of pesticide residues are also discussed.

New Trend in the Extraction of Pesticides from the Environmental and Food Samples Applying Microextraction Based Green Chemistry Scenario: A Review

This review focused on the green microextraction methods used for the extraction of pesticides from the environmental and food samples. Microextraction techniques have been explored and applied in various fields of analytical chemistry since its beginning, as evinced by the numerous reviews published. The success of any technique in science and technology is measured by the simplicity, environmentally friendly, and its applications; and the microextraction technique is highly successive. Deliberations were attentive to studies where efforts have been made to validate the methods through the inter-laboratory comparison study to assess the analytical performance of microextraction techniques against conventional methods. Succinctly, developed microextraction methods are shown to impart significant benefits over conventional techniques. Provided that the analytical community continues to put forward attention and resources into the growth and validation of the microextraction technique, a promising future for microextraction is forecasted.

Supramolecular solvent-based micro-extraction of pesticides in food and environmental samples

Supramolecular solvent-based micro-extraction is a very important green technique for the isolation and pre-concentration of pesticide residues in food and environmental samples prior to their chromatographic analysis. The attractive features of supramolecular solvent-based micro-extraction include its simplicity, high pre-concentration factor, fastness, accuracy, low cost, less consumption of chemical reagents and environmental friendliness. The supramolecular solvent is generated from a ternary mixture of amphiphiles, water and a water miscible dispersion and coacervating solvent. Tehydrofuran is one of the solvents commonly used as both a dispersion solvent and a coacervating agent. This paper gives a recent comprehensive review on the application of alkanols as amphiphiles during supramolecular solvent-based micro-extraction of pesticide residues in food and environmental samples. Other researchers used long chain fatty acids as amphiphiles during pesticide analysis in food and environmental samples using supramolecular solvent-based micro-extraction, and this is discussed in this paper. The incorporation of ferrofluids in supramolecular solvents enables phase separation using a magnet instead of the time-consuming centrifugation technique. This paper also gives a detailed review of the application of ferrofluid-based supramolecular solvent micro-extraction of pesticide residues in food and environmental samples.

Deep eutectic solvent dependent carbon dioxide switching as a homogeneous extracting solvent in liquid-liquid microextraction

A miscible-immiscible deep eutectic solvent (DES) containing monoethanolamine/4-methoxyphenol was used as an extraction solvent in a homogeneous liquid-liquid microextraction (HLLME). The method was used to preconcentrate chlorobenzenes in water samples followed by separating and analyzing them by gas chromatography-mass spectroscopy (GC-MS). A special feature of the new extraction method is that a green miscible solvent was used as an extractant in the HLLME method. The developed extraction technique provided enrichment factors in the range of 13.1-42.1 for extraction from only 1.0 mL of the aqueous sample solution. The effects of various experimental parameters were investigated and optimized. The optimal conditions were as follows: vortex time: 30.0 s, bubbling CO₂ gas: 1.0 min, salt concentration: 5.0% w/v, rate and time of centrifuge: 4000.0 rpm and 3.0 min, respectively, and DES volume: 30.0 µL. The limit of detections and the limit of quantifications for the four targeted analytes varied from 0.01-0.15 and 0.025-0.5 µg L^-1, respectively. The precision and long-term precision tests for the developed method were found to be less than 11.0%. Two real samples, including toilet air freshener and car perfume, were analyzed. The applied DES in the HLLME method provides a fast means of sample preparation for environmental aqueous sample solutions.

Application of Hydrophobic Magnetic Nanoparticles as Cleanup Adsorbents for Pesticide Residue Analysis in Fruit, Vegetable, and Various Soil Samples

A cleanup procedure based on hydrophobic magnetic nanoparticles for QuEChERS extraction followed by GC-MS method for the simultaneous determination of 16 organochlorine pesticides was developed. The type and amount of cleanup adsorbents (C18/GCB/Fe₃O₄/Fe₃O₄@Triton), the volume and polarity of the extraction solvent were optimized. The method was validated according to SANTE/11813/2017 and ICH/2005/Q2/R1 guidelines. Spiked-sample recoveries of 84-108% with RSD below 8% were obtained for all the tested pesticides in strawberry. Quantification was carried out using matrix-matched calibration plots, which displayed good linearity (R² > 0.99), the limits of quantification being less than the maximum residue limits (MRL) for food. The elaborated procedure with satisfactory results was applied in to determine the pesticides in fruit, vegetable (strawberries, avocadoes, watermelons, radishes, and flesh kiwis) and soil (agricultural, urban and lab-made) samples. The most frequently founded pesticide residues were 4,4'-DDE, 4,4'-DDD, lindane, and 4,4'-DDT, which in all cases were found to be below MRL. The highest concentration of 4,4'-DDT was founded in agricultural and lab-made soils.

A functionalized carbon nanotube nanohybrids-based QuEChERS method for detection of pesticide residues in vegetables and fruits

A self-separating, analyte-compatible, and efficient clean-up method for QuEChERS extracts was designed and developed based on dispersive solid-phase extraction using a branched polyethylenimine and nanoscale CaSO₄ functionalized carboxylated multi-walled carbon nanotubes (MWCNTs) nanohybrids as sorbent. The feasibility of using a self-separating strategy based on the functionalization of sorbent in a purification procedure was analyzed for the first time in this study. Compared to the traditional QuEChERS method, the proposed method is rapid and convenient without centrifugation of numerous samples in the clean-up process. The use of nanohybrids overcame the issue of low recoveries for planar pesticides, which are easily adsorbed using MWCNTs. A better clean-up capability of the nanohybrids to remove matrix interferences and reduce matrix effect was demonstrated compared with that of traditional clean-up sorbent primary secondary amine. The method was validated by determining twenty-eight pesticides in cucumber, cabbage, apple, and orange. Limits of detections were in the range of 0.0001-0.0026 mg/kg. Spike recoveries of pesticides were within 75.3 - 113.6%, with relative standard deviations less than 14.3% at levels 0.01 mg/kg and 0.1 mg/kg. The developed method was successfully applied to monitor the multi-residues.

Self-Assembled Three-Dimensional Microporous rGO/PNT/Fe3O4 Hydrogel Sorbent for Magnetic Preconcentration of Multi-Residue Insecticides

The purpose of this work was to develop a highly selective, sensitive, and reliable method for multi-residual analysis. A three-dimensional microporous reduced graphene oxide/polypyrrole nanotube/magnetite hydrogel (3D-rGOPFH) composite was synthesized and utilized as a magnetic solid-phase extraction (MSPE) sorbent to preconcentrate thirteen insecticides, including five organophosphorus (isocarbophos, quinalphos, phorate, chlorpyrifos, and phosalone), two carbamates (pirimor and carbaryl), two triazoles (myclobutanil and diniconazole), two pyrethroids (lambda-cyhalothrin and bifenthrin), and two organochlorines (2, 4′-DDT and mirex), from vegetables, followed by gas chromatography-tandem mass spectrometry. This method exhibited several major advantages, including simultaneous enrichment of different types of insecticides, no matrix effect, high sensitivity, and ease of operation. This is ascribed to the beneficial effects of 3D-rGOPFH, including the large specific surface (237 m2 g−1), multiple adsorption interactions (hydrogen bonding, electrostatic, π–π stacking and hydrophobic interaction force), appropriate pore size distribution (1–10 nm), and the good paramagnetic property. Under the optimal conditions, the analytical figures of merit were obtained as: linear dynamic range of 0.1–100 ng g−1 with determination coefficients of 0.9975–0.9998; limit of detections of 0.006–0.03 ng g−1; and the intra-day and inter-day relative standard deviations were 2.8–7.1% and 3.5–8.8%, respectively. Recoveries were within the range of 79.2 to 109.4% for tomato, cucumber, and pakchoi samples at the fortification levels of 5, 25, and 50 ng g−1. This effective and robust method can be applied for determining multi-classes of insecticide residues in vegetables.