Multiclass Pesticides Research Articles

Multiclass Pesticide Residue Analysis in Fruit and Vegetable Samples by Combining Acetone-Based Salting-Out Assisted Extraction with Dispersive Liquid-Liquid Microextraction

Isolation and enrichment of multiclass pesticides’ residue, namely, fungicides (benalaxyl), herbicides (atrazine), carbamate insecticides (carbofuran), organophosphate insecticides (chlorpyrifos), organochlorine insecticides (4,4′-DDT), and pyrethroid insecticides (bifenthrin), were made by combining acetone-based salting-out assisted extraction with the dispersive liquid-liquid microextraction (SADLLME) method, followed by high-performance liquid chromatography-diode array detection (HPLC-DAD). The effect of the type and volume of the extraction solvent in the pretreatment step, the volume of the disperser solvent (acetone extract), the type and volume of the extraction solvent, pH, and salt addition in the DLLME procedure was studied. Good coefficient of determination (R2 ≥ 0.9964) was obtained for all the target analytes. The limits of detection and quantification limits were between 2.1 and 4.5 and 5.7 and 12.9 µg/kg, respectively, with adequate enrichment factors ranging from 37.6 to 191. The recoveries of spiked blank tomato ranged from 86.8 to 109.5%. The limit of quantification of the proposed method was lower than the maximum residue limits set by the European Union. The repeatability and reproducibility of precisions ranged between 2.9 and 8.0 and 4.9 and 9.5%, respectively. The optimized and validated method was applied to quantify pesticides in tomato, pear, apple, and melon obtained from different markets. However, all target compounds studied in this work were not detected in any real samples applied. Overall, the work results revealed that the proposed method is useful for the sample extraction and preconcentration of the target analytes from fruits and vegetables.

SALLE combined with LD-DLLME for pesticides analysis in sugar and soil samples

In this study, a modified salting-out-assisted liquid-liquid extraction (SALLE) combined with low density dispersive liquid-liquid microextraction (LD-DLLME) has been developed for quantitative determination of multiclass pesticide residues (atrazine, diazinon, ametryn, terbutryn, chlorpyrifos, dimethametryn, 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE), 4,4'-dichlorodiphenyldichloroethane (4,4'-DDD) and 4,4'-dichloro- diphenyltrichloroethane (4,4'-DDT)) levels in sugar and soil samples coupled with gas chromatography–mass spectrometry (GC-MS) detection. The extract was enriched after combining SALLE to LD-DLLME and enrichment factor obtained ranged 30-121. Under the optimum conditions, the linearity of the method was in the range of 6.25–100 ng g-1 for atrazine, ametryn, terbutryn, dimethametryn and 4,4'-DDT, and in the range of 2.5–100 ng g-1 for diazinon, chlorpyrifos and 4,4'-DDD, and in the range of 1–100 for 4,4'-DDE with correlation coefficient of 0.992 or better. The limits of detection (LODs) ranged from 0.01–0.25 ng g-1. The precisions as %RSD, were below 10% for both matrices. The recoveries obtained from spiked sugar and soil samples at 5 and 50 ng g-1 ranged from 79 to 111%. The method was subsequently applied to real sugar and soil samples. All the pesticides investigated were not detected in the sugar sample. The soil sample was contaminated by atrazine and ametryn at concentration level of 0.3 and 0.2 ng g-1, respectively.
 
 KEY WORDS: SALLE, LD-DLLME, Extraction, Pesticide residues, Sugar, Soil
 
 Bull. Chem. Soc. Ethiop. 2021, 35(1), 1-16.
 DOI: https://dx.doi.org/10.4314/bcse.v35i1.1

Accurate mass screening of pesticide residues in wine by modified QuEChERS and LC-hybrid LTQ/Orbitrap-MS

In this research, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction procedure and Ultra-High Performance Liquid Chromatography-Orbitrap-Mass Spectrometry (UHPLC-Orbitrap-MS), were combined to obtain a sensitive and rapid method for the determination of multiclass pesticides in white and red wines. The optimization strategy involved the selection of buffering conditions, by applying different QuEChERS procedures and sorbents for the cleanup step in order to achieve acceptably high recoveries and low co-extractives in the final extracts. Identification was based on both accurate mass and retention time, while further confirmation was achieved by MS fragmentation. The method was evaluated in terms of linearity, recovery, precision, limit of detection (LOD) and quantification (LOQ), matrix effects (ME) and expanded uncertainty. The validated method was successfully applied to real samples (home-made and commercial) revealing the presence of two selected fungicides, in relatively low levels compared to the MRLs defined by the EU for vinification grapes.

Multiclass pesticide residue analysis in tobacco (Nicotiana tabacum) using high performance liquid chromatography-high resolution (Orbitrap) mass spectrometry: A simultaneous screening and quantitative method

Public exposure to pesticides through tobacco has attracted serious attention. Here we report a simultaneous screening and quantitation method for the non-target multiresidue analysis of pesticides in different tobacco types. The method involved extraction of a homogenate (20 g, containing 2 g tobacco) in ethyl acetate (10 mL), cleanup of 2 mL extract by dispersive solid phase extraction with PSA (50 mg)+C18 (50 mg)+GCB (25 mg)+MgSO4 (100 mg), followed by reconstitution in 1 mL acetonitrile:water (3:7) and analysis using HPLC with Quadrupole-Orbitrap mass spectrometry. The high resolution accurate mass analysis was performed through sequential full-scan (resolution=35000) and variable data independent acquisition (resolution=17500) events. When the method was evaluated in a mixture of 181 pesticides, it effectively minimised matrix interferences and false negatives. The target compounds included 5 pairs of isomers and 27 pairs of isobars, which were distinguished based on chromatographic separation, mass resolving power and/or unique product ions. The screening detection limit (SDL) for 86.4% of the test pesticides was set at 5 ng/g, while the remainder had the SDLs at 10 ng/g (9.3%) and 40 ng/g (4.3%). Nearly, 75% of the compounds showed recoveries of 70–120% at 10 ng/g. The rest of the compounds showed satisfactory recoveries at 40 and 100 ng/g. In all cases, precision-RSDs were < 20%. The established method demonstrated a successful performance in four different types of tobacco matrices while aligning with the guidelines of SANTE and US-FDA. Owing to its efficiency, the method is recommended for screening and quantitation of multiclass pesticides in tobacco.

Determination of 77 Multiclass Pesticides and Their Metabolitesin Capsicum and Tomato Using GC-MS/MS and LC-MS/MS.

A quick, sensitive, and reproducible analytical method for the determination of 77 multiclass pesticides and their metabolites in Capsicum and tomato by gas and liquid chromatography tandem mass spectrometry was standardized and validated. The limit of detection of 0.19 to 10.91 and limit of quantification of 0.63 to 36.34 µg·kg−1 for Capsicum and 0.10 to 9.55 µg·kg−1 (LOD) and 0.35 to 33.43 µg·kg−1 (LOQ) for tomato. The method involves extraction of sample with acetonitrile, purification by dispersive solid phase extraction using primary secondary amine and graphitized carbon black. The recoveries of all pesticides were in the range of 75 to 110% with a relative standard deviation of less than 20%. Similarly, the method precision was evaluated interms of repeatability (RSDr) and reproducibility (RSDwR) by spiking of mixed pesticides standards at 100 µg·kg−1 recorded anRSD of less than 20%. The matrix effect was acceptable and no significant variation was observed in both the matrices except for few pesticides. The estimated measurement uncertainty found acceptable for all the pesticides. This method found suitable for analysis of vegetable samples drawn from market and farm gates.

Analysis of multiple pesticide residues in rice by LC–MS/MS

A multiresidue method without cleanup step was validated for simultaneous determination of multiclass pesticide residues in rice. The extracted incurred residues of pesticides were separated on a reversed-phase column and quantified by tandem mass spectrometry (MS/MS). The method accuracy was in the range of 71–108%, and the precision was in the range of 4–20% for 25 out of 28 selected pesticides. The method quantification limits for 25 selected pesticides were below Codex and EU maximum residue limits (MRL). The selected 25 pesticides met the EU-SANTE and FAO/WHO Codex Alimentarius Commission method validation guidelines. The interday repeatability of the optimized method was between 4 and 18% (n = 6). The expanded uncertainty calculated for the optimized method ranged from 22 to 48%. The results obtained demonstrated the method's suitability for routine analysis. In total, 35 samples were analyzed of which, 22 samples (62%) were found to be contaminated with pesticides concentrations ranging from 0.010 to 0.297 mgkg−1.

Detection of multi-class pesticide residues with surface-enhanced Raman spectroscopy

The excessive use of pesticides disturbs the natural balance in the environment, creates resistance to pesticides and leads to water and food contamination. Therefore, the implementation of fast, robust and cost effective techniques for the monitoring of pesticides is required. In this work surface-enhanced Raman spectroscopy (SERS) was used for the detection of four common pesticides: atrazine, simazin, irgarol, and diuron. SERS is nowadays considered an effective technique for detection of various analytes in low concentration. Sensitivity of the SERS method depends on the type of substrate that can be either a colloidal solution of metal nanoparticles (NPs) or a metal surface with a suitable nanostructured topology. Here, we have investigated the application of silver nanospheres and silver nanoprisms as SERS substrates in pesticides detection. Colloids with spherical NPs were produced by chemical reduction while Ag nanoprisms were prepared by reducing silver nitrate with borohydride (with citrate as a stabilizing agent) and stirring under a UV lamp for 4 and 10 h. The SERS results have shown that, in the presence of synthesized NPs, it was possible to detect millimolar concentrations of aforementioned pesticides with the exception of diuron.

Development of A Liquid Chromatography-Mass Spectrometry Technique for Evaluation of Multi-class Pesticides in Rice Samples.

In the current study, a liquid chromatography coupled mass detector was set up to detect and quantify 108 pesticide residues in rice samples. QuEChERS method was applied for sample preparation and different validation parameters were determined to ensure the suitability of the method. The calibration curves were linear in the concentration 0.01-1.00 mg/kg with a coefficient of determination (R2) of more than 0.990 for all compounds. Based on signal to noise studies, the calculated LODs and LOQs were 0.005-0.060 mg/kg and 0.018-0.199 mg/kg, respectively; and acquired mean recoveries at three spiked levels (0.025, 0.200 and 0.800 mg/kg) were 72% - 117% with RSD < 20%. The developed method was used to investigate the occurrence of the studied pesticides in 65 internal and 65 foreign rice samples. The results showed that 14 internal and 15 imported samples were found to be contaminated 12 pesticides in the amounts between 0.027 mg/kg to 0.078 mg/kg and 0.031 mg/kg to 0.081 mg/kg, respectively. According to the Iranian regulations, with the exception of nine prohibited pesticides for rice production in Iran, bioallethrin, cypermethrin, deltamethrin, flutriafol, foramsulfuron, imazalil, phosphamidon, TCMTB, and triasulfuron, three permitted pesticides, cinosulfuron, triadimenol, and tricyclazole, found in positive rice samples were below MRLs established by Iranian National Standard Organization (INSO).

Multi-class pesticide analysis in cannabis oil using coated blade spray and solid-phase microextraction with liquid chromatography coupled to mass spectrometry

The application of solid-phase microextraction (SPME) coupled to mass spectrometry to provide a high-throughput and cost-effective solution to multi-residue analysis of pesticides in cannabis oil samples has not been extensively explored. In this work, the method development steps for the extraction of an initial target list of 74 pesticides from cannabis oil via SPME for analysis with both LC-MS/MS and coated blade spray (CBS) are presented. The exploration of a washing step to remove adhered oil whilst minimally desorbing extracted analytes along with the implementation of central composited design investigation to examine compound extraction kinetics in the non-polar matrix yielded a workflow that was validated via both instrumental techniques. Of the initial target list, 37 pesticides were found to be suitable for screening or quantitation via CBS with performance validated via LC-MS/MS. The majority of compounds were found to meet the EU SANTE guidelines for analysis (i.e. linearity, precision, accuracy) whilst reaching limits of quantitation below or at Health Canada minimum regulatory limits (majority at 10 ng/mL). Examination of factors contributing to poor quantitation of pesticides via CBS are shared and explored, such as contributing isobaric interference sourced from plant byproducts and carrier oil, and comparison of signal-to-noise values achieved in cannabis oil when compared to the cannabis-free medium-chain triglyceride oil used as a carrier oil to stress the importance of matrix-match method development.

Customized dispersive micro-solid-phase extraction device combined with micro-desorption for the simultaneous determination of 39 multiclass pesticides in environmental water samples

A dispersive micro-solid phase extraction (d-µ-SPE) procedure was developed for the simultaneous extraction of 39 multiclass pesticides, containing a variety of chemical groups (organophosphate, organochlorine, pyrethroid, strobilurin, thiocarbamate, triazole, imidazole, and triazine), from water samples. A customized d-µ-SPE glass device was combined with a multi-tube platform vortex and a micro-desorption unit (Whatman Mini-UniPrep G2 syringeless filter), which allowed the unique simultaneous desorption, extract filtration, and injection. A simplex-centroid mixture design and Doehlert design were employed to optimize the extraction conditions. The optimized extraction conditions consisted of an extraction time of 30 min, an addition of 6.74 % of NaCl into 100 mL of water sample, and a desorption time of 24 min with 500 µL of EtAc. The procedure provided a low limit of detection (LOD), ranging from 0.51 ng L−1 (4,4-DDE) to 22.4 ng L−1 (dimethoate), and an enrichment factor ranging from 72.5 (dimethoate) to 200 (tebuconazole). The relative recoveries of the pesticides from spiked freshwater and seawater ranged from 74.2 % (endrin) to 123 % (molinate). The proposed procedure was applied to detect the presence of multiclass pesticides in environmental water samples. Three pesticides commonly applied in Brazil, namely, malathion, dimethoate, and lambda-cyhalothrin, were detected in concentrations ranging from <LOD to 120 ng L−1 (dimethoate).

Magnetic Solid-Phase Extraction (MSPE) Using Magnetite-Based Core-Shell Nanoparticles with Silica Network (SiO2) Coupled with GC-MS/MS Analysis for Determination of Multiclass Pesticides in Water.

For the analysis of pesticide residues in water samples, various extraction techniques are available. However, liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are most commonly used. LLE and SPE extraction techniques each have their own disadvantages. The aim of the study was to develop an environment-friendly multi-residue method for determination of multiclass pesticides in environmental water samples (ground water, agricultural field/irrigation run-off water, etc.). The magnetic solid-phase extraction (MSPE) technique using surface-fabricated magnetic nano-particles was used for extraction of water samples, followed by quantification by gas chromatography tandem mass spectrometry. The developed multi-residue method was validated in terms of linearity, LOD, LOQ, recovery, and repeatability. Recovery data were obtained at the spiking concentration level of 1, 5, and 10 µg/L, yielding recoveries in the range of 70-120%. Overall, non-polar pesticides from all the groups, i.e., synthetic pyrethroid, organophosphorus, organochlorine, herbicides, and fungicides, show acceptable recovery percentages. Good linearity (r2 value ≥ 0.99) was observed at the concentration range of 0.5-100 µg/L. RSD values were found ≤ 18.8. The study shows that the method is specific, rapid, and low cost, as well as having a good linearity and recovery; thus, this method is applied in routine purposes for the analysis of pesticide residue in real water samples. Due to better adsorption ability, permeability, and magnetic separability, the functionalized nano-particles were found effective in the enrichment of 22 multiclass pesticides including organo-phosphorus, organo-chlorine, synthetic pyrethroid, herbicides, and fungicides.

Application of Multivariate Data Analysis to the Determination of Multiclass Pesticide Residues in Fruits and Vegetables using Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry

Design of experiment (DOE) was employed to develop a headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) method for multiresidue analysis. The significance of SPME parameters was determined using Placket-Burman (P-B) design. The main effect and the interaction effect of the significant factors were also determined followed by the optimization of the significant factors using central composite design (CCD). A Minitab® statistical software was used to generate both the 27-4 Placket-Burman and the central composite design matrix. The same statistical software was also employed in the determination of the optimum level of the significant parameters using surface response optimizer and desirability surface plot. The most significant factors are: extraction temperature (90%), extraction time (80%), the pH and stirring rate (50% and 60% respectively). The optimum parameters are: Temperature, 62 °C; time, 34 min; NaCl, 10%; stirring, 350rpm; pH, 6. The figures of merit of analytical methodologies was determined using an internal standard calibration method. The linearity of the developed method ranges from 1- 500 µg/kg and correlation coefficient (R2) greater than 0.99. The average recovery was found between 74 – 115% and relative standard deviation ranges from 1.1 – 14%. The developed method was used to analyze 14 multiclass pesticide residues in two fruit (pear and grape) and two vegetable (lettuce and broccoli) samples, and the method was found to be satisfactory with LOD between 0.17 – 7.34 µg/kg and LOQ ranges from 0.55 – 24.50 µg/kg. Keyword: Design of experiment (DOE), solid phase microextraction, response surface optimizer, pesticide residues, Central composite Design

Evaluation of LC-MS/MS methodology for determination of 179 multi-class pesticides in cabbage and rice by modified QuEChERS extraction

A method using modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) without clean-up step based on the sample dilution approach followed by the liquid chromatography coupled with the tandem mass spectrometry (LC-MS/MS) has been established for determination of 179 pesticide residues in cabbage and rice samples. Two different LC columns were used and their sensitivity was investigated regarding the sample volume. Evaluation of the matrix effect in context of sample dilution and applied extraction solvents was investigated. The method was validated according to Document SANTE/12682/2019. For cabbage samples, recoveries were 70–120% for concentration level of 5 μg/kg; and 70–115% for concentration level of 50 μg/kg; precision RSDr <17%; limits of detection and quantification were in the ranges of 0.4–5.5 and 1.2–16.7 μg/kg, respectively. For rice samples, recoveries were 70–109% for 10 μg/kg concentration; 70–115% for 100 μg/kg concentration; precision RSDr <14%, while limits of detection and quantification were in the ranges of 0.5–4.2 and 1.5–12.7 μg/kg, respectively.

Multidimensional capillary liquid chromatography-tandem mass spectrometry for the determination of multiclass pesticides in "sugarcane spirits" (cachaças).

Cachaça or "sugarcane spirit" is a Brazilian beverage considered the third most consumed beverage worldwide. Sugarcane, its raw material, is one of the main crops developed in the country, placing Brazil as the largest producer of this commodity on a global scale. Considering the growth in sugarcane production, many farmers use pesticides in their crops. However, excess pesticides can be accumulated in products derived from sugarcane, creating an environmental and public health concern. In this context, the development of analytical methods capable of identifying residues of pesticides in cachaças and other sugarcane-derived products is essential to ensure the beverage's quality. This work presents a method to quantify multiclass pesticides in Brazilian sugarcane spirits (cachaças) through an automated multidimensional system. The first dimension consists of an extraction column packed with a graphene-silica phase, followed by a capillary liquid chromatography-tandem mass spectrometry system as the second dimension. The method was optimized by an experimental design, in which the influence of three variables was evaluated on the extraction process: percentage of acetonitrile, loading flow, and loading time. Afterward, twenty-two cachaças were analyzed to ascertain the applicability of the proposed method. The analyses reported five samples containing clomazone (a type of herbicide widely used in sugarcane production). The method showed good linearity under optimized conditions, with correlation coefficients greater than 0.981, and limits of detection and quantification of 5μgL-1 and 10μgL-1, respectively. The herein discussed results suggest that the proposed method could be a practical option for identifying pesticides in beverages. Graphical Abstract.

CVD grown carbon nanofibers: an efficient DSPE sorbent for cleanup of multi-class pesticide residue in high fat and low water commodities by QuEChERS using GC-ECD.

An inexpensive, effective, and efficient dispersive solid-phase extraction (DSPE) sorbent was developed as an alternative totraditionally used sorbents (primary secondary amine and C18) for fatty matrices using theQuEChERS method. Catalytic chemical vapor deposition grown carbon nanofibers dispersed on activated carbon fibers (Ni-ACF/CNF) having aBET specific surface area of738 (m2/g) were for thefirst time evaluated as a DSPE material for sample cleanup before gas chromatographic analysis. Based on cleanup performance and recoveries, 10mg of Ni-ACF/CNF was found optimalfor the determination of twenty-seven multi-class pesticides in high fat and low water commodities/matrices (peanut, soybean, sesame, and flaxseed). The recoveries obtained for all analytes were in the range ~ 72 to ~ 117%, with relative standard deviation values ≤ 15%. The limits of detection and quantification values were 0.7-4.2ng/g and 2.3-13.9ng/g, respectively. The matrix match calibration curve was linear in the range 20-500ng/g with a correlation coefficient of ≥ 0.993. The results reveal thatthe Ni-ACF/CNF is a competent DSPE sorbent, similar to primary secondary amines and C18sorbent materials, for pesticide determination by QuEChERS methods in high fat and low water commodities. Graphical abstract.

Determination of 66 pesticide residues in livestock products using QuEChERS and GC-MS/MS.

Determinations of 66 pesticide residues in different matrices including beef, pork, chicken, eggs, and milk were conducted using GC-MS/MS combined with the quick easy cheap effective rugged safe (QuEChERS) method for sample extraction. A high linearity was achieved in the concentration range from 2.5 to 1000µg/L (R 2 ≥ 0.99), and the limit of quantification for multi-class pesticides ranged from 0.74 to 23.1µg/kg. The recovery ranged from 70.0 to 120%, while the reproducibility of the measurements was between 0.23 and 19.9%. Monitoring was conducted for livestock products purchased from local markets. Chlorpyrifos and fenitrothion in beef and chlorpyrifos in pork were detected below the maximum residue limits for the respective samples. No detectable residues were found in the other samples. Due to its high efficiency, reproducibility, and simple analytical operation, the proposed method can be applied to the regular monitoring of multi-residue pesticides in livestock products.

Single-Laboratory Validation of a Multi-residue Method for Simultaneous Analysis of Multi-class Pesticides in Turmeric by Liquid Chromatography Tandem Mass Spectrometry.

For years, turmeric has been used in several cuisines worldwide because of its proven health benefits. However, as its cultivation often involves applications of polar and semi-polar pesticides, their residues might cause health hazards to consumers. The dearth of a validated LC-MS/MS method for the residue analysis of these pesticides in turmeric has warranted the present study. The aim was to develop and validate a multi-residue method for simultaneous determination of multi-class pesticides in turmeric (both rhizome and powder) by LC-MS/MS. Both the rhizome and powder samples (1 kg) were soaked in water for 30 min, followed by homogenization. Each homogenate (2 g) was mixed with 10 mL water, and extracted with acetonitrile (10 mL) in the presence of acetic acid and NaCl. The extract was cleaned by using dispersive solid phase extraction (dSPE) with graphitized carbon (5 mg/mL) sorbent. The cleaned extract was measured by LC-MS/MS with a runtime of 20 min. The method was validated on 211 multi-class pesticides. The method performance was satisfactory at 10 ng/g and higher levels, in compliance with the SANTE/12682/2019 guidelines. The dSPE cleanup was effective in minimizing the matrix effects. The use of matrix-matched calibrations specific for turmeric powder and rhizome corrected all recoveries within the satisfactory range of 70-120%. The precision -RSDs were <20% for all test pesticides. The Horwitz ratio and measurement uncertainty results were satisfactory as well. As the method was convenient, selective, accurate, and repeatable, it is recommended for regulatory and commercial testing purposes. For the first time, this study reports a validated LC-MS/MS method for the multi-residue analysis of pesticides in turmeric. The method provided a high throughput analysis of multi-class pesticides in turmeric rhizome and powder matrices with satisfactory selectivity, sensitivity, accuracy, and precision. The method performance satisfied the requirements of the SANTE/12682/2019 guidelines, and the method sensitivity complied with the EU-MRL requirements.

Development and validation of a multiresidue method for pesticides and selected veterinary drugs in animal feed using liquid- and gas chromatography with tandem mass spectrometry.

Animal feeds are often reported to be contaminated with chemical residues, and when present above the maximum legal limit, these compounds can cause harmful effects to consumers of animal produce. Thus, animal feed safety is an important regulatory concern. The aim of this study was to optimise a multiresidue method for the simultaneous analysis of multi-class pesticides and a number of frequently used veterinary drugs using LC-MS/MS and GC-MS/MS. The method was validated in a range of feed matrices, including maize feed, poultry feed and mixed feed concentrate. The optimised sample preparation workflow involved extraction of feeds (5g) with ethyl acetate (10mL), followed by a freezing step (at -20°C) used for eliminating the matrix co-extractives. The extract was further cleaned by dispersive solid phase extraction with a combination of primary secondary amine, C18 and florisil sorbents. From the cleaned-extract, an aliquot was analysed by GC-MS/MS, while another portion of it was solvent-exchanged to acetonitrile:water (50:50) and then analysed by LC-MS/MS. This method effectively minimised the matrix interferences. A total of 192 pesticides was analysed by GC-MS/MS within a runtime of 22min. The LC-MS/MS method was validated for 187 compounds including 17 veterinary drugs. For most of the compounds, the limit of quantification (LOQ) was 0.01mg/kg. The recoveries at LOQ and higher levels ranged between 70% and 120%, with precision-RSDs of < 20%. The method provided a precise analysis in a wide range of market-feed samples. As shown, the method is suitable for regulatory and commercial testing purposes.

Development of a Multiresidue QuEChERS–DLLME—Fast GC–MS Method for Determination of Selected Pesticides in Yogurt Samples

In this study, a combination of modified quick easy cheap effective rugged and safe extraction (QuEChERS) and dispersive liquid–liquid microextraction (DLLME) has been proposed for the extraction and preconcentration of multiclass pesticide residues from yogurt samples prior to their determination by fast gas chromatography–mass spectrometry. Factors influencing DLLME efficiency, including type and volume of extractive solvent, mixing type, salt addition, and extraction time were evaluated. The obtained extract from the first step of QuEChERS was subsequently adjusted by DLLME using tetrachloroethane as an extractive solvent. The method was fully validated within the optimized extraction parameters. The recoveries of pesticides were between 70 and 120% with relative standard deviations less than 20%. The limits of detection ranged between 0.04 ng/L and 2.00 μg/L, and the limits of quantification ranged from 0.12 ng/L to 6.60 μg/L. The optimized method was employed for the determination of pesticides in real samples of yogurts.

GC-MS/MS를 이용한 축산물 중 29종 농약의 동시다성분 분석법 검증

GC-MS/MS를 이용한 축산물 중 29종 농약의 동시다성분 분석법 검증