A new environment-friendly supramolecular solvent-based liquid phase microextraction coupled to high performance liquid chromatography for simultaneous determination of six phenoxy acid herbicides in water and rice samples

Switchable deep eutectic solvent as green and efficient media for liquid-phase microextraction of phenoxyacetic acid herbicides in water and food matrices

In this work, a switchable deep eutectic solvent (SDES) based on fatty acid and polyetheramine ion pair was prepared for liquid-phase microextraction (LPME) of phenoxyacetic acid herbicides in drinking water, beverage and honey matrices. The as-synthesized SDES equipped with an interesting characteristic of fast and reversible polarity switching, achieving homogeneous extraction and rapid bi-phase separation simultaneously. Several key parameters affecting the extraction performance were investigated comprehensively by Box-Behnken design. Under the optimal conditions, the method exhibited excellent linearity (15-4000 μg L-1), low detection limits (3-5 μg L-1), desirable precision (RSD < 8.1 %), and satisfactory recovery (72.6-98.7 %). More importantly, the introduction of SDES can simplify the pre-treatment procedure, shorten extraction time (4 min), and avoid the usage of traditional organic solvent during the whole extraction process. In addition, the switching mechanism of SDES was characterized by FT-IR and 1H NMR, and the forming mechanism of SDES was investigated using density-functional theory. The green of the method was estimated using the analytical ecological scale, the analytical green calculator, and the green analytical procedure index. The cytotoxicity of SDES was investigated and the result displayed that toxicity of the SDES was very low with the EC50 > 500 mg/L. Therefore, the proposed method was green and efficient and revealed considerable application prospects for the extraction of trace analytes from complex materials.

Investigation of the removal of diclofop methyl herbicide by peroxy electrocoagulation process and kinetic and cost analysis

Pesticides containing chlorine, which are released during agricultural activities, are chemical substances that mix with surface and underground waters and have toxic, carcinogenic, and mutagenic effects on the entire living ecosystem. Due to their chemically stable structure, conventional water and wastewater treatment techniques such as coagulation, flocculation, and biological oxidation do not entirely remove these chemical substances. Therefore, before releasing them into the environmental receptor, these chemical substances must be transformed into harmless products or mineralized through advanced oxidation processes. When we look at the literature, there are not many studies on methods of removing diclofop methyl from aquatic media. Our study on the removal of diclofop methyl herbicide from aquatic media using the peroxy electrocoagulation method will provide the first information on this subject in the literature. In addition, this treatment method will contribute significantly to filling an important gap in the literature as an innovative approach for diclofop methyl removal. Moreover, peroxy electrocoagulation, which produces less sludge, provides treatment in a short time, and is economical, has been determined to be an advantageous process. The effects of conductivity, pH, H2O2 concentration, current, and time parameters on the removal of diclofop methyl were investigated using a GC-MS instrument. Kinetics, energy consumption, and cost calculations were also made. Under the optimum conditions determined (pH = 5, H2O2 = 500 mg/L, NaCl = 0.75 g/L, current density = 2.66 mA/cm2), the peroxydic electrocoagulation process resulted in a diclofop methyl removal efficiency of 79.2% after a 25-min reaction. When the experimental results were analyzed, it was found that the results fitted the pseudo-second-order kinetic model.

Primary amine citrate-based supramolecular designer solvent: Preconcentration of ochratoxin A for determination in foods by liquid chromatography

BACKGROUND

Supramolecular solvents are nanostructured liquids that are separated from colloidal solutions of amphiphilic compounds as a result of self-assembly of amphiphiles and coacervation under changing conditions. They are considered to be designer solvents as their properties can be tailored to a specific analytical task by controlling the conditions of their formation (amphiphile, coacervation inducer, medium, concentration of components). The discovery of new extraction systems based on supramolecular solvents and their application to relevant analytical tasks are of great importance for the advancement of environmentally-friendly sample preparation.

RESULTS

A novel green liquid-phase microextraction approach involving in situ formation of 1-octylamine citrate followed by preconcentration of ochratoxin A from aqueous extract of food sample in supramolecular solvent droplets was developed. The extraction system was carefully characterized. The density of the solvent allowed it to be to retrieved from the extraction system by its solidification. The alkaline nature of the obtained extract allowed the use of acetic acid for its dissolution instead of more toxic organic solvents followed by high-performance liquid chromatography with fluorometric detection. An excellent extraction recovery of 99 % and a satisfactory enrichment factor of 8.3 were achieved. The limit of detection was 0.5 μg kg-1, while the calibration plot was linear over the range of 1.5-50 μg kg-1. Cereal and roasted coffee bean samples were successfully analyzed with a relative bias less than 20 %.

SIGNIFICANCE

In the present work, a phenomenon of supramolecular solvent formation based on primary amine citrate was presented for the first time. Tetrabutylammonium bromide was investigated as a coacervation agent in an extraction system, and possible interactions responsible for its ability to induce phase separation in a micellar solution of primary amine citrate were described. The critical micelle concentration of 1-octylamine citrate in aqueous solution of tetrabutylammonium bromide was firstly determined.

Ultrasound and surfactant-assisted dispersive liquid-liquid microextraction prior to poly(ethylene oxide)-mediated stacking in CE for highly sensitive determination of barbiturates in human fluids

This study developed a facile, highly sensitive technique for extracting and quantifying barbiturates in serum samples. This method combined ultrasound and surfactant-assisted dispersive liquid-liquid microextraction with poly(ethylene oxide)-mediated stacking in capillary electrophoresis. Factors influencing the extraction and stacking performance, such as the type and volume of extraction solvents, the type and concentration of surfactant, extraction time, salt additives, sample matrix, solution pH, and composition of the background electrolyte, were carefully studied and optimized to achieve the optimal detection sensitivity. Under the optimized extraction (injecting 140 μL C2 H4 Cl2 into 1 mL of sample with pH 4 (5 mM sodium phosphate containing 0.05 mM Tween 20 and sonication for 1 min) and separation conditions (150 mM tris(hydroxymethyl)aminomethane-borate with pH 8.5 containing 0.5% (m/v) poly(ethylene oxide)), the limits of detection (signal-to-noise ratio = 3) of five barbiturates ranged from 0.20 to 0.33 ng/mL, and the calculated sensitivity improvement ranged from 868- to 1700-fold. The experimental results revealed excellent linearity (R2  > 0.99), with relative standard deviations of 2.1%-3.4% for the migration time and 4.3%-5.7% for the peak area. The recoveries of the spiked serum samples were 97.1% -110.3%. Our proposed approach offers a rapid and practical method for quantifying barbiturates in biological fluids.

ZIF-67-modified magnetic nanoparticles for extraction of phenoxy carboxylic acid herbicides

Phenoxy carboxylic acid (PCA) herbicides are commonly used herbicides that can easily accumulate in soil, groundwater, crops, and vegetable surfaces. Thus, they pose a serious risk to human health. Accurate detection of trace amounts of PCAs in various matrixes is crucial. Herein, ZIF-67-modified magnetic nanoparticles (MNPs, ZIF-67@Fe3O4) were prepared by growing ZIF-67 on the surface of Fe3O4 MNPs. The introduction of ZIF-67 improved the dispersion of Fe3O4 nanoparticles in water and enhanced their extraction performance for PCAs. When an eluent consisting of ammonia water and acetonitrile (5% : 95%; v/v) was employed, 10 mg of ZIF-67@Fe3O4 displayed optimal extraction performance for PCAs in a 20 mL sample solution at a pH of 3. We achieved a limit of detection ranging from 0.014 μg L-1 to 0.056 μg L-1 for four types of PCA herbicides by using the newly developed method. Notably, the values were considerably lower than the maximum concentration levels of PCAs in drinking water set by the Environmental Protection Agency. The relative recovery rate of PCAs using ZIF-67@Fe3O4 ranged from 83.75% to 117.07% when applied to river water and apple samples. These results demonstrate the great potential of ZIF-67@Fe3O4 in determining the residues of organic pesticides in real samples.

Application of phosphonium deep eutectic solvents as extractants in ultrasound-assisted dispersive liquid-liquid microextraction for preconcentration of trace amounts of herbicides in drainage ditches waters

In this study, an efficient preconcentration method was presented that is based on dispersive liquid-liquid microextraction taking the advantage of newly synthesized phosphonium deep eutectic solvents used as extractants and ultrasound probe as a dispersing agent. The extracts obtained were analyzed by high-performance liquid chromatography. To optimize the five most important factors for the microextraction procedure a central composite design plan was used. Under optimal conditions (140 μl of extractant, 60 mg of NaCl, pH = 2.0, 120 s of extraction time with ultrasound probe as the dispersing agent, 16 min of centrifugation for phase separation), the proposed method allowed to achieve good precision with RSD between 3.2% and 9.7% at 1.0, 5.0 and 40.0 ng ml levels. The preconcentration factors were equal to 42, 39, and 41, and the limits of detection 0.128, 0.103, and 0.135 ng/ml for dicamba, 2-methyl-4-chlorophenoxyacetic acid, and 2-methyl-4-chlorophenoxypropionic acid, respectively. The proposed method was successfully applied for the determination of chlorophenoxy acid herbicides in water samples from drainage ditches with a good recovery in the range of 70%-93%.

Potentiometric MIP-Modified Screen-Printed Cell for Phenoxy Herbicides Detection

In this study, a molecularly imprinted polymer (MIP)-based screen-printed cell is developed for detecting phenoxy herbicides using 2-methyl-4-chlorophenoxyacetic acid (MCPA) as the template. MCPA is a phenoxy herbicide widely used since 1945 to control broadleaf weeds via growth regulation, primarily in pasture and cereal crops. The potentiometric cell consists of a silver/silver chloride pseudo-reference electrode and a graphite working electrode coated with a MIP film. The polymeric layer is thermally formed after drop-coating of a pre-polymeric mixture composed of the reagents at the following molar ratio: 1 MCPA: 15 MAA (methacrylic acid): 7 EGDMA (ethylene glycol dimethacrylate). After template removal, the recognition cavities function as the ionophore of a classical ion selective electrode (ISE) membrane. The detected ion is the deprotonated MCPA specie, negatively charged, so the measurements were performed in phosphate buffer at pH 5.5. A linear decrease of the potential with MCPA concentration, ranging from 4 × 10^-8 to 1 × 10^-6 mol L^-1, was obtained. The detection limit and the limit of quantification were, respectively, 10 nmol L^-1 and 40 nmol L^-1. A Nernstian slope of about -59 mV/dec was achieved. The method has precision and LOD required for MCPA determination in contaminated environmental samples.

Simultaneous Preconcentration of Triazole Fungicide Residues Using In-Situ Coacervative Extraction Based on a Double-Solvent Supramolecular System Prior to High Performance Liquid Chromatographic Analysis

An in situ coacervative extraction (IS-CAE) based on a double-solvent supramolecular system coupled to liquid–liquid microextraction is investigated for extraction and enrichment of triazole fungicides. The formation of a double-solvent supramolecular system was generated by in situ formation and used as an extraction solvent for the coacervative extraction method. No disperser solvent was required. This new double-solvent supramolecular system has a higher extraction ability than any of its components alone. The different factors that could affect the extraction capability were studied and optimized, including the type of double extractant and its volume, salt addition, vortex time, and centrifugation time. Under optimum extraction conditions, this method provides high enrichment factors (EFs) of 73–318 with low limits of detection (LODs) of 0.3–1 μg L⁻¹ and limits of quantitation (LOQs) of 1–3 μg L⁻¹. In addition, the proposed method was prosperously applied for the determination of triazole fungicides in water, fruit juice, and soy milk samples.

Hexagonal boron nitride nanosheets based magnetic solid phase extraction for the extraction of phenoxy carboxylic acid herbicides from water samples followed by high-performance liquid chromatography-tandem mass spectrometry

High-efficiency caption of pesticide residue is of vital significance for environmental safety monitoring. Herein, a hexagonal boron nitride nanosheets-based magnetic composite (Fe₃O₄@h-BNNSs) was synthesized and applied for the magnetic solid phase extraction (MSPE) of five phenoxy carboxylic acid (PCA) herbicides from water samples. Based on the π-π interaction, hydrogen bond and halogen bond, the Fe₃O₄@h-BNNSs composite showed excellent adsorption ability towards PCA herbicides. Several main variables that influenced the extraction efficiencies of PCA herbicides were investigated and optimized via single-factor experiment. Combining this Fe₃O₄@h-BNNSs composite-based MSPE with high-performance liquid chromatography-tandem mass spectrometry, a novel sensitive method for the analysis of PCA herbicides was developed. Under the most favorable conditions, the proposed method displayed good linear ranges (20.0-10000.0 ng L^-1), low limits of detection (5.6-10.3 ng L^-1), satisfactory precisions (1.1-6.8%) and recoveries (76.6-107.2%). Overall, the present work can be a versatile and worthy utility for the determination of PCA herbicides from different water samples.

Automation in quantifying phenoxy herbicides and bentazon in surface water and groundwater using novel solid phase extraction and liquid chromatography tandem mass spectrometry

The occurrence of phenoxy herbicides is a financial and regulatory concern for drinking water treatment plants. This paper presents a new method of quantification for nine phenoxy-acids and bentazon in different water samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). The method is based on an automated solid phase extraction (SPE) process that applied hydrophilic modified polystyrene and divinylbenzene cartridges at low pH (<2.0). Main advantages of the presented method include the reduced consumption of organic solvent in extraction and the fully automated sample pre-concentration. The method is thus more environmentally-friendly. In the quantification step, five stable isotopically labelled analogues were used as internal standards to account for the losses during sample preparation and to calibrate the ion source response under the mass spectrometric detection. The method was optimized in terms of sample preparation and subsequent LC-MS/MS separation to obtain reliable measurement of the analyte concentration during real sample analysis. The method quantification limit was between 1.5 and 10.0 ng/L for target compounds in surface water and groundwater samples. The method was validated at three fortification levels between 10.0 and 1000 ng/L, and the results showed fit-for-purpose recovery with appropriate precision at low concentration levels. The method was also utilized to analyse thirty-two actual water samples from different sources. Forty percent of the analysed samples contained detectable level of herbicides, ranging from 1.91 to 40.5 ng/L. The concentrations of targeted herbicides in our study were comparable to those found in water samples in other regions of world.

Development of poly(vinyl alcohol)/chitosan/aloe vera gel electrospun composite nanofibers as a novel sorbent for thin-film micro-extraction of pesticides in water and food samples followed by HPLC-UV analysis

Schematic presentation of applying PVA/CA/CS/AV composite nanofibers as the extraction phase in thin-film micro-extraction (TFME) of six pesticide compounds prior to HPLC-UV analysis.

Magnetic molecularly imprinted polymer for the simultaneous selective extraction of phenoxy acid herbicides from environmental water samples

A selective magnetic molecularly imprinted polymer (MMIP) was synthetized with 4-chloro-2-methylphenoxyacetic acid as template and 4-vinylpiridine as monomer in presence of vinylized magnetite nanoparticles. Scanning electron microscopy, nitrogen adsorption-desorption isotherms, Fourier transform infrared spectrometry and vibrating sample magnetometry were applied to characterize the resulting material. The synthesized MMIP was applied as sorbent in magnetic molecularly imprinted solid-phase extraction (MMISPE) for selective extraction of a mixture of the five herbicides 4-chloro-2-methylphenoxyacetic acid (MCPA), 4-(4-chloro-2-methylphenoxy)butyric acid (MCPB), mecoprop (MCPP), fenoxaprop (FEN) and haloxyfop (HAL). Several parameters affecting the extraction conditions were optimized to achieve the best extraction performance. The best MMISPE combined with HPLC-DAD gave detection and quantification limits between 0.33 and 0.71 μg L^-1 and 1.1-2.4 μg L^-1, respectively, were obtained. The precision of the whole method provided RSD values below 7.3%, and the accuracy was demonstrated by the analysis of several water samples of different origins, with recoveries ranged from 77 to 98%. Moreover, a remarkable re-usability of the MMIP sorbent, more than 65 uses without losses in extraction capacity, was obtained.

Development of monolith/aminated carbon nanotubes composite-based solid-phase microextraction of phenoxycarboxylic acids herbicides in water and soil samples

In this study, a new adsorbent based on monolith/aminated carbon nanotubes composite was facilely prepared and employed as the extraction phase of multiple monolithic fibers solid-phase microextraction for the capture of phenoxycarboxylic acids herbicides. The adsorbent was fabricated by mingling aminated carbon nanotubes in the poly (allylthiourea-co-ethylene glycol dimethacrylate) monolith. Various techniques were employed to characterize the morphology, structure, and pore size of the prepared adsorbent. The proposed microextraction method displayed satisfactory capture performance towards studied analytes through multi-interactions such as hydrogen-bonding, hydrophobic and π-π interactions. Under the optimized conditions, a sensitive and reliable method to quantify trace analytes in water and soil samples was developed. The limits of detection were in the ranges of 0.13-0.25 μg/L and 0.20-0.61 μg/kg for water and soil samples, respectively. The practicality of the introduced method was demonstrated by applying it to monitor the contents of studied analytes in environmental water and soil samples. Satisfactory fortified recoveries (76.4-119%) and reproducibility were obtained. The achieved results well demonstrated that the suggested microextraction technique can efficiently extract phenoxycarboxylic acids and the developed method exhibits a promising potential for reliable and sensitive quantification of trace analytes in complex samples.

Analytical Extraction Methods and Sorbents' Development for Simultaneous Determination of Organophosphorus Pesticides' Residues in Food and Water Samples: A Review

Extensive use of organophosphorus pesticides in agriculture leads to adverse effects to the environment and human health. Sample preparation is compulsory to enrich target analytes prior to detection as they often exist at trace levels and this step is critical as it determines the concentration of pollutants present in samples. The selection of a suitable extraction method is of great importance. The analytical performance of the extraction methods is influenced by the selection of sorbents as sorbents play a vital role in the sensitivity and selectivity of an analytical method. To date, numerous sorbent materials have been developed to cater to the needs of selective and sensitive pesticides' detection. Comprehensive details pertaining to extraction methods, developed sorbents, and analytical performance are provided. This review intended to provide a general overview on different extraction techniques and sorbents that have been developed in the last 10 years for organophosphorus pesticides' determinations in food and water samples.

An ionic covalent organic framework for rapid extraction of polar organic acids from environmental waters

An ionic covalent organic framework (Fe₃O₄@EB-TFB-iCOF) as a polar adsorbent was synthesized and characterized. It was applied in the magnetic solid phase extraction (MSPE) of four polar organic acids, namely, 2-(2,4,5-trichlorophenoxy)propionic acid, 2-methyl-4-chlorophenoxy acetic acid, naphthyloxyacetic acid, and naphthylacetic acid. The organic acids were detected by high performance liquid chromatography-ultraviolet analysis (HPLC-UV). A method for the determination of organic acids based on MSPE-HPLC-UV was established. The method shows good linear regression (R²≥ 0.9950), high precision (1.53-3.80%, n = 6), and low detection limit (0.10-0.49 ng mL^-1). The recovery rate of environmental water samples ranges from 73.3% to 101.0%. This method provides a possibility for high sensitivity analysis of polar organic acids.

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.

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.

Highly specific nanobody against herbicide 2,4-dichlorophenoxyacetic acid for monitoring of its contamination in environmental water

2,4-dichlorophenoxyacetic acid (2,4-D), a widely used herbicide, is a small organic chemical pollutant in the environment. To develop a nanobody-based immunoassay for monitoring trace levels of 2,4-D, a step-wise strategy for the generation of nanobodies highly specific against this small chemical was employed. Firstly, we synthesized three novel haptens mimicking 2,4-D and assessed their influence on the sensitivity and specificity of the existing antibody-based assay. Polyclonal antibodies (pAb) from rabbits showed good sensitivity and moderate specificity for 2,4-D, pAb from llama based on selected haptens showed similar performance when compared to those from rabbits. Secondly, nanobodies derived from llama were generated for 2,4-D by an effective procedure, including serum monitoring and one-step library construction. One nanobody, NB3-9, exhibited good sensitivity against 2,4-D (IC₅₀ = 29.2 ng/mL) had better specificity than the rabbit pAb#1518, with no cross-reactivities against the 2,4-D analogs tested. Thirdly, one-step fluorescent enzyme immunoassay (FLEIA) for 2,4-D based on a nanobody-alkaline phosphatase (AP) fusion was developed with IC₅₀ of 1.9 ng/mL and a linear range of 0.4-8.6 ng/mL. Environmental water samples were analyzed by FLEIA and LC-MS/MS for comparison, and the results were consistent between both methods. Therefore, the proposed step-wise strategy from hapten design to nanobody-AP fusion production was successfully conducted, and the resulting nanobody based FLEIA was demonstrated as a convenient tool to monitor 2,4-D residuals in the environment.

A rapid and simple method for the removal of dyes and organophosphorus pesticides from water and soil samples using deep eutectic solvent embedded sponge

A new treatment method using a deep eutectic solvent embedded melamine sponge (DES-MS) was studied for the removal of organic pollutants from water and soil samples. Five organophosphorus pesticides (OPPs) consisting of azinphos-methyl (AZP), parathion-methyl (PRT), fenitrothion (FNT), diazinon (DIZ) and chlorpyrifos (CPF), and two dyes including acid blue 29 (AB29) and malachite green (MG) were used as the model pollutants. DESs were easily prepared from tetrabutylammonium bromide (TBABr) and various fatty acids. The synthesised DESs were loaded into the sponge before being utilized for the removal of the studied pollutants. After the removal, the residual OPPs or dyes in the supernatant was quantified by high performance liquid chromatography or derivative spectrophotometry, respectively. The proposed method was simple, rapid, environmentally friendly and effective with the removal efficiency higher than 70% for various samples. Moreover, the removal of various dyes was successfully achieved with the efficiency greater than 65% under the optimum condition.

Modified QuEChERS extraction method followed by simultaneous quantitation of nine multi-class pesticides in human blood and urine by using GC-MS

Organophosphate, carbamate and pyrethroid pesticides are the most common insecticides used worldwide. They may cause chronic poisoning in farmers and acute poisoning in homicidal or suicidal cases. The determination of trace levels of these pesticides in human blood and urine is very challenging. This study focuses on a simultaneous quantitation method that was developed and validated for multi-class nine pesticides belonging to organophosphate, carbamate and pyrethroid classes in human blood and urine. Target pesticides were extracted from blood and urine using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction method. Capillary column DB-35 ms (15 m × 0.25 mm, 0.25 µm) was used for chromatography with a 0.079 ml/min flow rate of carrier gas at constant pressure mode. Quantitation of sulfotep, phorate, carbofuran, chlorpyriphos, profenophos, triazophos, pyriproxyfen, lambda-cyhalothrin and permethrin was performed by mass spectrometer equipped with electron impact ionization source using selected ion monitoring (SIM) mode. The lower and upper limits of quantitation for all nine pesticides were 0.01 mg/L and 2.0 mg/dL respectively. The proposed method was proved to be simple, fast, sensitive, and robust. It has been applied to the analysis of 9 pesticides samples.