Screening of multiclass pesticide residues in maca andMoringa oleiferaby a modified QuEChERS sample preparation procedure and UPLC-ESI-MS/MS analysis

In the present study, a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was proposed for the simultaneous analysis of 75 pesticides in maca andMoringa oleiferawith ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). The developed method was validated in accordance with linearity, linear range, limit of detection, limit of quantification, accuracy, precision, and matrix effect. Each analyte had good linearity (R-2> 0.99) in the corresponding concentration range. The method LOD and LOQ values of all the analytes ranged from 0.01 mu g kg(-1)to 303.35 mu g kg(-1)and 0.03 mu g kg(-1)to 1011.15 mu g kg(-1), respectively. The recoveries (n= 6) of the analyzed pesticides were in the range of 75.92-113.43%. The RSDs of precision were between 0.60% and 7.36%. All matrix effect values ranged from 81.79% to 118.71% and 80.36% to 119.64% in maca andMoringa oleifera, respectively. The analysis of 103 samples showed the presence of isofenphos-methyl in some of them. The method had a good application prospect and could be used as a general approach for the quantitative determination of pesticide residues in food.