Trace analysis of some organophosphorus pesticides in rice samples using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography

Deep eutectic solvent-based pressurized liquid extraction combined with dispersive liquid-liquid microextraction of organophosphorus pesticide residues in egg powder prior to high-performance liquid chromatography analysis

Herein, a deep eutectic solvent (DES)-based miniaturized pressurized liquid extraction in combination with DES-based dispersive liquid-liquid microextraction (DLLME) was developed for the extraction of organophosphorus pesticides (parathion-methyl, triazophos, parathion, diazinon, and phoxim) from egg powder samples prior to their analysis by a high-performance liquid chromatography-diode array detector. In this work, first, the analytes' extraction was done by a pressurized liquid phase extraction for effective extraction of the analytes from the solid matrix, and then they were concentrated on a DLLME for more concentration of the analytes to reach low limits of detections. The use of DESs was done in both steps to omit the use of toxic organic solvents. Satisfactory results including high extraction recoveries (74-90%), great repeatability (relative standard deviations equal or less than 4.3% and 5.3% for intra- and inter-day precisions), and low limits of detection (0.11-0.29 ng/g) and quantification (0.38-0.98 ng/g) were attained under the optimum conditions. Lastly, the suggested approach was utilized for the determination of the studied pesticides in various egg powder samples marketed in Tabriz, Iran.

Keggin-type polyoxometalate embedded polyvinylidene fluoride for thin film microextraction of organophosphorus pesticides

The present research is the first report on the application of Keggin-type phosphotungstic acid/polyvinylidene fluoride membrane. This compound as a simple, cost-effective and novel sorbent was used for the extraction and pre-concentration of two organophosphorus pesticides in real samples in the thin film solid-phase microextraction (TFME) method. TFME as one of the sub-branches of solid phase microextraction resolves the problems of SPME methods, including their limited absorption capacity. These extraction methods have a high surface-to-volume ratio, which improves their sensitivity compared to other geometries. Under optimal conditions, the limit of detections (LODs), the limit of quantifications (LOQs), and relative standard deviation (RSD) of this method varied in the ranges of 0.29-0.31 μg L-1, 0.96-1.0 μg L-1, and 3.9%-6.2%, respectively. This method showed a linear dynamic range (LDR) of 1.0-500 μg L-1 with a coefficient of determination (r2) above 0.9978. This promising method was used to analyze malathion and diazinon.

Determination of chlorantraniliprole 18.5% SC in the paddy ecosystem and its risk assessment

Chlorantraniliprole belongsto theanthranilic diamide group is widely used against broad range of lepidopteron pests in a variety of vegetable and rice pests includingyellow rice stem borer and leaf folder. Supervised field trials were conducted duringRabi (2018-2019) and Kharif (2019) to evaluate the dissipation pattern and risk assessment of chlorantraniliprole 18.5% SC in paddy ecosystem following foliar application at 30 and 60 g a.i. ha^-1 in two different cropping seasons.Modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) technique was used for the extraction of CAP residues with acetonitrile and determined by LC-MS/MS (ESI +).The limit of quantification (LOQ) was 0.01 µg g^-1 for paddy leaf, straw, husk, and brown rice, respectively and 0.005 µg g^-1 for soil. The average recoveries obtained were 84.30-88.92% from paddy leaf, 94.25-97.81% from straw, 90.21-93.38% from husk, 93.57-96.40% from brown rice and 89.93-91.14% from soil. The residues in paddy leaf dissipated within 35-40 days with a half-life of 4.33-5.07 days in Rabi and 3.92-4.86 days in Kharif at 30 and 60 g a.i. ha^-1, respectively. The residues in soil dissipated within 15-21 days with a half-life of 14.44-15.75 days in Rabi and 13.33-14.44 days in Kharif at respective doses. At harvest chlorantraniliprole residues were not detected in straw, husk, and brown rice. The dietary risk of paddy leaf (green fodder) for cattle was found safe for consumption as the hazard index is less than one. Soil ecological risk assessment was found to be less than one (RQ < 0.1) for earthworms (Eisenia foetida) and arthropods (Aphidiusrhopalosiphi). The presentmethod could be useful inthe analysis ofchlorantraniliproleresidues in different cereals and vegetable crop ecosystems and application at recommended dose is safe for the final produce at harvest.

Rapid and reliable detection and quantification of organophosphorus pesticides using SERS combined with dispersive liquid-liquid microextraction

Rapid and reliable detection and quantification of pesticide residues in complex matrices by surface enhanced Raman spectroscopy (SERS) remain challenging due to the low level of target molecules and the interference of nontarget components. In this study, SERS was combined with dispersive liquid-liquid microextraction (DLLME) to develop a rapid and reliable method for the detection of organophosphorus pesticides (OPPs). In this method, DLLME was used to extract and enrich two representative OPPs (triazophos and parathion-methyl) from a liquid sample, and a portable Raman spectrometer was used to analyze the separated sediment using homemade gold nanoparticles colloids as enhancing substrates. The results showed that the developed method displayed good sensitivity and stability for the detection and quantification of triazophos and parathion-methyl with R² ≥ 0.98. The calculated limits of detection (LODs) in the simultaneous detection of triazophos and parathion-methyl were 2.17 × 10^-9 M (0.679 ppb) and 2.28 × 10^-8 M (5.998 ppb), and the calculated limits of quantification (LOQs) were 7.23 × 10^-9 M (2.26 ppb) and 7.62 × 10^-8 M (19.098 ppb), respectively. Furthermore, the developed SERS method was successfully applied to the detection of triazophos and parathion-methyl in apple juice with recoveries between 78.07% and 110.87% and relative standard deviations (RSDs) ≤ 2.06%. Therefore, the developed DLLME facilitated liquid SERS method exhibited good sensitivity and stability for the rapid detection and quantification of OPPs and had the potential to be applied to the rapid detection of OPPs in complex matrices.

Rapid analysis of triazine herbicides in fruit juices using evaporation-assisted dispersive liquid-liquid microextraction with solidification of floating organic droplets and HPLC-DAD

A rapid and convenient analytical procedure (evaporation-assisted dispersive liquid-liquid microextraction with solidification of floating organic droplets) is advanced for determining the concentrations of triazine herbicide residues (e.g. simazine and atrazine) in fruit juices via HPLC-DAD. The technique involves adding 1-dodecanol (low density) and dichloromethane (high density) to the test solution to act as the extraction and volatile solvents, respectively. Calcium oxide is added to generate heat to accelerate the evaporation of dichloromethane, whereupon the 1-dodecanol quickly disperses into small droplets to complete the microextraction process. Thus, there is no need to use a dispersive solvent and heating equipment is also not required. The floating 1-dodecanol is subsequently frozen using an ice bath to facilitate its separation from the sample. Under optimal conditions (250 μL of 1-dodecanol (extraction solvent), 150 μL of CH₂Cl₂ (volatile solvent), 1250 mg of CaO, and an extraction time of 60 s) the detection procedure is linear over the range 0.05-5 μg mL^-1 (with R > 0.99). The limits of detection (LOD) and quantification (LOQ) were determined to be 0.0022-0.0034 μg mL^-1 and 0.0073-0.0113 μg mL^-1, respectively. The recovery of simazine and atrazine in three fruit juices ranged between 78.5% and 96.4% with a relative standard deviation <8.2%. Therefore, the proposed approach can be effectively adopted to analyze the triazine herbicide content in fruit juices. The method has been proved to be simple, reliable, and remarkably efficient.

Novel deep eutectic solvent-based liquid phase microextraction for the extraction of estrogenic compounds from environmental samples

Steroid hormones, such as estrone (E1), 17β-estradiol (E2), 17β-ethinylestradiol (EE2) and estriol (E3) are a group of lipophilic active substances, synthesized biologically from cholesterol or chemically. A pH-switchable hydrophobic deep eutectic solvent-based liquid phase microextraction (DES-LPME) technique was established and combined with gas chromatography-mass spectroscopy for the determination of estrogenic compounds in environmental water and wastewater samples. A DES was synthesized using l-menthol as HBA and (1S)-(+)-camphor-10-sulfonic acid (CSA) as HBD, and used as a green extraction solvent. By adjusting the pH of the solution, the unique behavior of the DES in the phase transition and extraction of the desired analytes was investigated. The homogenization process of the mixture is done only by manual shaking in less than 30 seconds and the phase separation is done only by changing the pH and without centrifugation. Some effective parameters on the extraction and derivatization, such as molar ratio of DES components, DES volume, KOH concentration, HCl volume, salt addition, extraction and derivatization time and derivatization prior or after extraction were studied and optimized. Under the optimum conditions, relative standard deviation (RSD) values for intra-day and inter-day of the method based on 7 replicate measurements of 20 ng L⁻¹ of estrogenic compounds and 10 ng L⁻¹ for internal standard in different samples were in the range of 2.2–4.6% and 3.9–5.7%, respectively. The calibration graphs were linear in the range of 0.5–100 ng L⁻¹ and the limits of detection (LODs) were in the range of 0.2–1.0 ng L⁻¹. The relative recoveries of environmental water and wastewater samples which have been spiked with different levels of target compounds were 91.0–108.8%.

A pH-switchable hydrophobic deep eutectic solvent-based liquid phase microextraction (DES-LPME) technique was established and combined with gas chromatography–mass spectroscopy for the determination of estrogenic compounds in environmental samples.

Trace analysis of organophosphorus pesticide residues in fruit juices and vegetables by an electrochemically fabricated solid-phase microextraction fiber coated with a layer-by-layer graphenized graphite/graphene oxide/polyaniline nanocomposite

Herein, a solid-phase microextraction pencil lead fiber coated with a layer-by-layer graphenized graphite/graphene oxide/polyaniline nanocomposite (GG/GO/PANI) was fabricated by an in situ electrochemical technique for the trace analysis of organophosphorus pesticide residues in packed grape and apple juice and also fresh tomato samples. The effects of various parameters, including the type of desorption solvent, adsorption time, desorption time, pH, salt addition, and stirring rate, on the extraction efficiency of the studied pesticides were investigated and accordingly, these parameters were optimized. The proposed fiber demonstrated desirable linear ranges (0.01-300 μg L-1) with good correlation coefficients (R2 ≥ 0.996) as well as low limits of detection (0.003-0.03 μg L-1) for the studied pesticides. The relative standard deviations (n = 5) for the extraction of 50 μg L-1 of each analyte were less than 7 and 11.5% for inter and intra-day precisions, respectively. This fast, facile, and repeatable electrochemical fabrication method produced a porous and homogeneous coating. The proposed fiber demonstrated good extraction efficiency, high stability, and long life-time despite being low cost. The successful application of the proposed fiber for the trace determination of pesticides in complex food matrices was proven by the satisfactory relative recoveries of 80.7-116.5%.

Control of Organophosphorus Pesticides Residues in Honey Samples Using a Miniaturized Tandem Preconcentration Technique Coupled with High Performance Liquid Chromatography

Background : In the present work, a miniaturized sample preparation method based on combination of dispersive solid phase extraction and temperature–induced homogenous liquid–liquid microextraction has been proposed for the extraction and preconcentration of some organophosphorus pesticides (parathion–methyl, triazophos, parathion, diazinon, and phoxim) from honey samples prior to their analysis by high performance liquid chromatography–ultraviolet detection. Methods: In this method, initially the analytes were adsorbed onto a sorbent (C18) and then desorbed by the use of cyclohexyl amine as an eluent. In the next step, the eluent was mixed with water thermostated at 0 °C to obtain a homogenous solution. By increasing the temperature, the solubility of cyclohexyl amine in water was decreased and led to formation of dispersed fine droplets in the whole of solution. These droplets go up through the solution and collected on top of the solution. Finally, an aliquot of the organic phase was sucked in a microsyringe and injected into the separation system for analysis. Results: Under the optimum experimental conditions, limits of detection and quantification were calculated to be in the ranges of 0.90–1.75 and 3.0–5.8 ng g–1 in honey samples, respectively. Enrichment factors and extraction recoveries were in the ranges of 148–183 and 59–73%, respectively. The relative standard deviations varied from 2–4% and 4–5% for intra– (n = 6) and inter–day (n = 4) precisions, respectively. Conclusion: The suggested approach was satisfactorily utilized to the analysis of 21 honey samples. The proposed miniaturized tandem sample pretreatment method enhanced the sensitivity of the instrumental analysis.

Organochlorine pesticides contamination in agricultural soils of southern Iran

There is limited information about pesticide contamination in Iran's agricultural land, particularly in plains producing exportable fruits. The aim of this investigation was to evaluate the concentration of organochlorine pesticides (OCPs) including hexachlorocyclohexane (HCH), heptachlor, dichloro-diphenyl-trichloroethane (DDT), chlordane (CHL), and their isomers compounds in agricultural soils of southern Iran. A total of 28 topsoil samples were collected from agricultural lands of Dalaki and Shabankare areas, Bushehr, Iran. In Dalaki area, the mean value of ΣHCH (α, β, γ, δ), ΣDDT (o,p-DDE, o,p-DDD, o,p-DDT, p,p-DDE, p,p-DDD, p,p-DDT, and DDT), and ΣCHL (Trans-chlordane, Cis-chlordane, Heptachlor-exo-epoxide, and Heptachlor) was found to be 0.411 ng/g (dry weight, dw), 4.37 ng/g dw, and 2.04 ng/g dw, respectively. In Shabankare area the mean value of ΣHCH, ΣDDT, and ΣCHL was measured to be 1.38 ng/g dw, 11.99 ng/g dw, and 1.62 ng/g dw, respectively. The concentration trend of pesticides in both areas was as follows: DDT > CHL > HCH. Source identification indicated recent usage of HCH and DDT in the studied areas. Obtaining a cis-chlordane/trans-chlordane ratio greater than one in Shabankare farmlands showed that chlordane was not used recently. The health risk assessment showed that children and adults groups in both areas are exposed to negligible cancer risk. More serious attempts are necessary to reduce usage of OCPs during the agricultural process and the protection of soil and human health in the studied areas.

Knowledge, attitude and practices of farmers about pesticide use, risks, and wastes; a cross-sectional study (Kermanshah, Iran)

This study was aimed to investigate the knowledge, attitude, and behavior of farmers about the pesticide use and wastes, and to determine the factors affecting the use of pesticides and their health effects, in agricultural lands located in Kermanshah province, western Iran. Three hundred eleven (311) farmers were included in this study, and filled a structured questionnaire containing questions about their basic information, their knowledge and attitude regarding pesticides, and their practices for pesticide disposal. In addition, the type and amount of pesticide consumption, and the health symptoms during the last year were recorded. Prevalence ratios and linear regression were used to evaluate the association between the different factors, and health symptoms and the amount of pesticide use, respectively. The majority of respondents had not been trained formally for the use of pesticides before. Approximately 10%, 45%, and 17% of pesticides contained highly hazardous, moderately hazardous, and slightly hazardous compounds, respectively. The farmers mainly had incorrect knowledge about pesticides and their risks, and used incorrect and high-risk methods for handling and application of pesticides and relevant wastes. Health symptoms were more associated with age ≥ 65, having no education, having income < 482 USD, not trained for pesticide use, and applying highly hazardous pesticides. In addition, the factors contributing to the amount of pesticide use included age, education level, and pesticide training. In order to reduce the amount of pesticide released to the environment, comprehensive training programs and implementing a waste management system could be effective.

Determination of β-Agonist Residues in Animal-Derived Food by a Liquid Chromatography-Tandem Mass Spectrometric Method Combined with Molecularly Imprinted Stir Bar Sorptive Extraction

A novel clenbuterol molecularly imprinted polymer (MIP)-coated stir bar was prepared and applied to the determination of six β-agonists in animal-derived food. Characterization and various parameters affecting adsorption and desorption behaviours were investigated. The extraction capacities of clenbuterol, salbutamol, ractopamine, mabuterol, brombuterol, and terbutaline for MIP coating were 3.8, 2.9, 3.1, 3.5, 3.2, and 3.3 times higher, respectively, than those of the NIP coating, respectively. The method of MIP-coated SBSE coupled with HPLC-MS/MS was developed. The recoveries in pork and liver samples were 75.8-97.9% with RSD from 2.6 to 5.3%. Limits of detection (LODs) and limits of quantification (LOQs) were 0.05-0.15 μg/kg and 0.10-0.30 μg/kg, respectively. Good linearities were obtained for six β-agonists with correlation coefficients (R²) higher than 0.994. These results indicated the superiority of the proposed method in the analysis of β-agonists in a complex matrix.

Simultaneous determination of three organophosphorus pesticides in different food commodities by gas chromatography with mass spectrometry

A sensitive and selective gas chromatography with mass spectrometry method was developed for the simultaneous determination of three organophosphorus pesticides, namely, chlorpyrifos, malathion, and diazinon in three different food commodities (milk, apples, and drinking water) employing solid-phase extraction for sample pretreatment. Pesticide extraction from different sample matrices was carried out on Chromabond C18 cartridges using 3.0 mL of methanol and 3.0 mL of a mixture of dichloromethane/acetonitrile (1:1 v/v) as the eluting solvent. Analysis was carried out by gas chromatography coupled with mass spectrometry using selected-ion monitoring mode. Good linear relationships were obtained in the range of 0.1-50 μg/L for chlorpyrifos, and 0.05-50 μg/L for both malathion and diazinon pesticides. Good repeatability and recoveries were obtained in the range of 78.54-86.73% for three pesticides under the optimized experimental conditions. The limit of detection ranged from 0.02 to 0.03 μg/L, and the limit of quantification ranged from 0.05 to 0.1 μg/L for all three pesticides. Finally, the developed method was successfully applied for the determination of three targeted pesticides in milk, apples, and drinking water samples each in triplicate. No pesticide was found in apple and milk samples, but chlorpyrifos was found in one drinking water sample below the quantification level.

Evaluation of alternative sorbents for dispersive solid-phase extraction clean-up in the QuEChERS method for the determination of pesticide residues in rice by liquid chromatography with tandem mass spectrometry

Many compounds are used for pest control during the production and storage of rice, making it necessary to employ multiclass methods for pesticide residues determination. For this purpose, QuEChERS-based methods are very efficient, fast and accurate, and improvements in the clean-up step are important, especially for complex matrices, like cereals. In this work, different sorbents such as chitosan, florisil(®) , alumina, diatomaceous earth, graphitized carbon black, besides the commonly used primary secondary amine and octadecylsilane, were evaluated for dispersive solid-phase extraction clean-up in acetate-buffered QuEChERS method for the determination of residues of 20 representative pesticides and one metabolite in rice by liquid chromatography coupled to tandem mass spectrometry. The sorbent C18 presented the best results, however, chitosan showed similar results, and the best performance among the unconventional sorbents evaluated. The method limit of quantification, attending accuracy (70-120% recovery) and precision (RSD ≤20%) criteria, ranged from 5 to 20 μg/kg. Results showed that chitosan is an effective alternative to reduce analysis costs, maintaining the method reliability and accuracy.