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This paper describes an extensive study in which a multiclass QuEChERS based approach was optimized for determination of 150 pesticides and 7 mycotoxins in table olives. Three versions of QuEChERS were evaluated and compared (unbuffered, citrate and acetate buffering). A combination of EMR-Lipid cartridges and liquid nitrogen or freezer freezing out were tested for clean-up of the oily olive extracts. Analysis of the extracts were performed by LC-MS/MS triple quadrupole. The best results were achieved using acetate QuEChERS with liquid nitrogen for clean-up. For validation, organic olives were ground and spiked at 4 concentrations with pesticides and mycotoxins ( n = 5). The linearity of the calibration curves was assessed by analyzing calibration standards of 7 concentrations which were prepared separately in acetonitrile and in blank olive extract ( n = 5). The validation study demonstrated that the calculated r was ≥0.99 for 144 pesticides and 6 mycotoxins, when the calibration curves were prepared in matrix extract, showing satisfactory linearity. Matrix effects were within the range of ±20% for only 46 pesticides and one mycotoxin. Then, to ensure reliable quantification, calibration standards had to be matrix-matched. In accuracy experiments 138 pesticides and 6 mycotoxins presented recoveries from 70 to 120% and RSD ≤ 20% for at least 2 of the 4 spike concentrations evaluated, being successfully validated. The integrated QuEChERS and LC-MS/MS method meet MRL for 11 of the 21 pesticides regulated for olives in Brazil and for 132 pesticides which are regulated in the EU law. Eleven commercial table olive samples were analyzed and 4 of them tested positive for pesticides. All the positive samples violate the Brazilian law and one sample violates also the European law.2 was ≥0.99 for 144 pesticides and 6 mycotoxins, when the calibration curves were prepared in matrix extract, showing satisfactory linearity. Matrix effects were within the range of ±20% for only 46 pesticides and one mycotoxin. Then, to ensure reliable quantification, calibration standards had to be matrix-matched. In accuracy experiments 138 pesticides and 6 mycotoxins presented recoveries from 70 to 120% and RSD ≤ 20% for at least 2 of the 4 spike concentrations evaluated, being successfully validated. The integrated QuEChERS and LC-MS/MS method meet MRL for 11 of the 21 pesticides regulated for olives in Brazil and for 132 pesticides which are regulated in the EU law. Eleven commercial table olive samples were analyzed and 4 of them tested positive for pesticides. All the positive samples violate the Brazilian law and one sample violates also the European law.

A simple and rapid method for simultaneous determination of pesticides and mycotoxins in red wine is presented. Sample preparation approach, called direct injection, consists of a sequence of only three steps: centrifugation, dilution and filtration. The analysis of extracts were performed by UPLC-MS/MS for determination of pesticides and mycotoxins. The method was assessed for linearity, limits of detection and quantification, matrix effects, selectivity, accuracy and precision. For recovery experiments, mycotoxins were divided in two groups according to their sensitivity in the UPLC-MS/MS system. More than 80% of the mycotoxins were reliably quantified at the lowest spike level studied (1 μg kg -1 for group 1 and 50 μg kg -1 for group 2). From the 185 evaluated pesticides, 144 showed acceptable results at 10 μg kg -1 , the lowest spiked level. Matrix effects were, in most of the cases, negative, and that was observed for both pesticides and mycotoxins., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This paper describes the optimization and validation of an acetonitrile based method for simultaneous extraction of multiple pesticides and mycotoxins from raw coffee beans followed by LC-ESI-MS/MS determination. Before extraction, the raw coffee samples were milled and then slurried with water. The slurried samples were spiked with two separate standard solutions, one containing 131 pesticides and a second with 35 mycotoxins, which were divided into 3 groups of different relative concentration levels. Optimization of the QuEChERS approach included performance tests with acetonitrile acidified with acetic acid or formic acid, with or without buffer and with or without clean-up of the extracts before LC-ESI-MS/MS analysis. For the clean-up step, seven d-SPE sorbents and their various mixtures were evaluated. After method optimization a complete validation study was carried out to ensure adequate performance of the extraction and chromatographic methods. The samples were spiked at 3 concentrations levels with both mycotoxins and pesticides (with 6 replicates at each level, n = 6) and then submitted to the extraction procedure. Before LC-ESI-MS/MS analysis, the acetonitrile extracts were diluted 2-fold with methanol, in order to improve the chromatographic performance of the early-eluting polar analytes. Calibration standard solutions were prepared in organic solvent and in blank coffee extract at 7 concentration levels and analyzed 6 times each. The method was assessed for accuracy (recovery %), precision (RSD%), selectivity, linearity (r 2 ), limit of quantification (LOQ) and matrix effects (%)., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The goal of this work was to evaluate the efficiency of several sorbents on removal fats from edible oils (olive, soya and sunflower) during the clean-up step for posterior determination of 165 pesticides by UHPLC-QqQ-MS/MS system. The extraction procedure employed in this work was the citrate version of QuEChERS method followed by a step of freezing out with dry ice and clean-up evaluation using i) PSA with magnesium sulfate (d-SPE); ii) magnesium sulfate and Z-sep sorbent (d-SPE); iii) Z-sep (column SPE) and iv) Agilent Bond Elut QuEChERS Enhanced Matrix Removal-Lipid (EMR-Lipid). After evaluation of the recovery results at 10, 20 and 50μgkg(-1), the EMR-Lipid showed important advantages comparing to the other sorbents evaluated, such as better recovery rates and RSD%. The method was validated at the three concentrations described above. Analytical curves linearity was evaluated by spiking blank oil samples at 10, 20, 50, 100 and 500μgkg(-1). The method demonstrated good recoveries values between the acceptable range of 70-120% and RSD%<20 for most of evaluated pesticides. In order to evaluate the performance of the method, this same procedure was employed to other oils such as soya and sunflower with very good results., (Copyright © 2016 Elsevier B.V. All rights reserved.)

An acetonitrile-based extraction method for the analysis of 169 pesticides in soya grain, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive and negative electrospray ionization (ESI) mode, has been optimized and validated. This method has been compared with our earlier published acetone-based extraction method, as part of a comprehensive study of both extraction methods, in combination with various gas chromatography-(tandem) mass spectrometry [GC-MS(/MS)] and LC-MS/MS techniques, using different detection modes. Linearity of calibration curves, instrument limits of detection (LODs) and matrix effects were evaluated by preparing standards in solvent and in the two soya matrix extracts from acetone and acetonitrile extractions, at seven levels, with six replicate injections per level. Limits of detection were calculated based on practically realized repeatability relative standard deviations (RSDs), rather than based on (extrapolated) signal/noise ratios. Accuracies (as % recoveries), precision (as repeatability of recovery experiments) and method limits of quantification (LOQs) were compared. The acetonitrile method consists of the extraction of a 2-g sample with 20 mL of acetonitrile (containing 1% acetic acid), followed by a partitioning step with magnesium sulphate and a subsequent buffering step with sodium acetate. After mixing an aliquot with methanol, the extract can be injected directly into the LC-MS/MS system, without any cleanup. Cleanup hardly improved selectivity and appeared to have minor changes of the matrix effect, as was earlier noticed for the acetone method. Good linearity of the calibration curves was obtained over the range from 0.1 or 0.25 to 10 ng mL(-1), with r(2)>or=0.99. Instrument LOD values generally varied from 0.1 to 0.25 ng mL(-1), for both methods. Matrix effects were not significant or negligible for nearly all pesticides. Recoveries were in the range 70-120%, with RSD

Part of a comprehensive study on the comparison of different extraction methods, GC-MS(/MS) and LC-MS/MS detection methods and modes, for the analysis of soya samples is described in this paper. The validation of an acetone-based extraction method for analysis of 169 pesticides in soya, using LC-MS/MS positive and negative electrospray ionisation (ESI) mode, is reported. Samples (5 g) were soaked with 10 g water and subsequently extracted with 100 mL of a mixture of acetone, dichloromethane and light petroleum (1:1:1), in the presence of 15 g anhydrous sodium sulphate. After centrifugation, aliquots of the extract were evaporated and reconstituted in 1.0 mL of methanol, before direct injection of the final extract (corresponding with 0.05 g soya mL(-1)) into the LC-MS/MS system. Linearity, r(2) of calibration curves, instrument limit of detection/quantitation (LOD/LOQ) and matrix effect were evaluated, based on seven concentrations measured in 6-fold. Good linearity (at least r(2)> or =0.99) of the calibration curves was obtained over the range from 0.1 or 0.25 to 10.0 ng mL(-1), corresponding with pesticide concentrations in soya bean extract of 2 or 5-200 microg kg(-1). Instrument LOD values generally were 0.1 or 0.25 ng mL(-1). Matrix effects were negligible for approximately 90% of the pesticides. The accuracy, precision and method LOQ were determined via recovery experiments, spiking soya at 10, 50, 100 microg kg(-1), six replicates per level. In both ESI modes, method LOQ values were mostly 10 or 50 microg kg(-1) and more than 70% of pesticides analysed by each mode met the acceptability criteria of recovery (70-120%) and RSD (< or =20%), at one or more of the three levels studied. A fast, easy and efficient method with acceptable performance was achieved for a difficult matrix as soya, without cleanup.