In this study, we have evaluated the efficiency of different sorbents for the cleanup step in multiresidue analysis of pesticides in fatty vegetable matrices using modified QuEChERS method. The three different matrices tested (brown rice, soybean and soybean oil) were partitioned using acetonitrile and hexane prior to cleanup step. The extraction efficiency of solvents was compared to acetonitrile, acetonitrile+hexane. Afterward, the supernatant was purified using different sorbents; PSA, C18, C18+PSA, and Z-Sep. The different cleanup strategies were compared for a group of 321 representative pesticides in terms of recovery rates, matrix effects, extract cleanliness and precision using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS). The best extraction efficiencies in soybean matrix were obtained using C18+PSA, while the results for matrices were pretty similar amongst the different sorbents with an overall lower performance in terms of matrix effects and recovery rates compared to soybean data, particularly in soybean oil due to the higher complexity and concentration of co-extracted species. On the other hand, the average reproducibility was clearly better when C18+PSA sorbent was employed in all selected matrices for most pesticides (RSD &lt; 10% for 178, 115, and 152 pesticides in brown rice, soybean and soybean oil, respectively). The best results in terms of matrix effects were also obtained with C18+PSA; with signal suppression lower than 20% for 52%, 66% and 39% of pesticides tested in brown rice, soybean and soybean oil, respectively. Using C18+PSA as a cleanup sorbent, limits of quantitation using UHPLC–MS/MS, ranged from 0.01 to 0.5 mg/kg. As a conclusion, the combination of C18+PSA sorbent appears to be a more suitable method because it can be reduced the matrix effect rather than the other sorbents.

Comparison of cleanup efficiency for multiresidue analysis of pesticides in soybean by liquid chromatography tandem mass spectrometry

256th National Meeting (2018)

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