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For the first time, an analytical method for the multiresidue analysis of multiclass pesticides in sesame seeds using liquid- and gas chromatography with tandem mass spectrometry (LC-MS/MS and GC-MS/MS) was developed and validated. At first, the sample was comminuted after adding water (1:2 w/v). The sample preparation workflow included acetonitrile extraction, followed by freeze-out of the extract at -80°C with a subsequent cleanup by dispersive solid phase extraction (dSPE) (100 mg of C 18  + 150 mg of MgSO 4 for LC-MS/MS and 100 mg of C 18  + 25 mg florisil + 150 mg of MgSO 4 for GC-MS/MS). As noted, these cleanup steps were quite effective in removing the fatty co-extractives. The optimised sample preparation method effectively minimised the matrix effects and offered a limit of quantification (LOQ) of 0.01 mg/kg for most compounds. The LC-MS/MS and GC-MS/MS methods were validated at three levels (0.01, 0.02 and 0.05 mg/kg) for 222 and 220 compounds respectively. The method accuracy and precision complied with the performance criteria of the SANTE/12682/2019 analytical quality control procedure. The results of the intra-laboratory (involving six analysts) and inter-laboratory studies (involving eight accredited laboratories) were comparable for all pesticides. Considering its performance efficiency and alignment with the regulatory guidelines, this method can be implemented across the food testing laboratories for the monitoring of pesticide residues in sesame seeds., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We developed a method for the hydrolysis of amitraz, and its degradation products 2,4-dimethylphenyl-N'-methylformamidine (DMPF) and 2,4-dimethylformamide (DMF) into 2,4-dimethylaniline (DMA), directly from QuEChERS extracts. The hydrolysis product DMA was analysed using liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) in the positive ion mode with DMA D6 as an internal standard. Validation of DMPF and amitraz via DMA, following hydrolysis directly from the QuEChERS raw extracts, was performed at 0.05 mg kg(-1) and at 0.5 mg kg(-1). Individual recoveries of amitraz and DMPF, determined as DMA, ranged between 100 and 120% and between 96 and 118% respectively and the relative standard deviations (RSDs) below 5.2% and below 9.5% respectively (n=5 at each spiked level). Successful validation for amitraz, and DMPF at 0.01 mg kg(-1), was also conducted following fivefold pre-concentration of QuEChERS extracts prior to hydrolysis. Pear samples with a history of amitraz treatment, containing residues of the amitraz metabolite DMPF but no detectable residues of amitraz or its other metabolites, DMF and DMA, were extracted using the QuEChERS method. DMPF-results obtained using direct LC-MS/MS analysis were found to be comparable with DMA-results obtained when the same extracts were subjected to alkaline hydrolysis, suggesting that DMPF constituted virtually the only source of DMA in the analysed pears and that the determination of amitraz (sum) in pears does not necessarily require a cumbersome method involving cleavage to DMA., (Copyright © 2014 Elsevier Ltd. All rights reserved.)