In this study, we have evaluated the effect of extraction and clean-up for pesticide classes in multi-residue pesticide analysis in four samples, such as brown rice, orange, green pepper and soybean chosen as representatives of starch, organic acid, high chlorophyll and fatty acid containing samples, respectively. The different extraction and clean-up steps were compared for 45 classes of 121 pesticides in terms of recovery, matrix effect, extract cleanliness and precision using UHPLC–MS/MS. Of the 45 classes, 37 classes were less affected by the extraction and clean-up steps. The log P of the pesticides in these classes ranged from 1.2 to 5.3, and the average recovery of the homogenizing, vortexing and shaking used in the extraction step was 85.2%. The number of pesticides satisfying the recovery of 70 ~ 120% in PSA, C18, C18+PSA, and Z-Sep used in the subsequent clean-up steps was 56 pesticide. On the other hand, the 8 classes, such as carbamate, N-methyl carbamate, sulfonylurea, urea, unclassified, pyrethroid, nereistoxin, and triazine, were affected by both extraction and clean-up steps. The recovery of 27 pesticides belonging to the 8 classes was out of the range, because of the log P was -1.21 ~ 0.2. Exceptionally the log P values of amitraz, etofenprox, and pyrethrin were over 5.0. Comparison of matrix effects for different samples showed high variability for some residues such as N-methyl carbamate. It was indicated that the amount of co-extracting compounds that cause ionization suppression of pesticides depends on the agricultural products as well as on the sample preparation method employed. In summary, since the pesticides of various classes are affected by the extraction and clean-up step, these findings can serve as a basis for the development of more accurate analytical methods.<br/>

Efficiency evaluation of extraction and clean-up for multi pesticides by LC-MS/MS in agricultural commodities

2019 Fall National Meeting

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