LC-MS/MS Determination of Residual Amounts of 31 Pesticides in Peaches

A portion of peel or pulp of peaches was extracted with acetonitrile by a pulper;shook with NaCl and MgSO4 for salting-out, and the supernatant was taken to mix with PSA and centrifuge for purification. After filtering through filter-membrane, the filtrate was diluted with water and used for LC-MS/MS analysis. Agilent Eclipse plus C18 RRHT column was used for chromatographic separation, with mixtures of (A) 5 mmol·L-1 NH4-formate solution (containing formic acid) and (B) CH3CN with various ratios as mobile phase in gradient elution. ESI+ and mode of dynamic multi-reaction monitoring were adopted in MS/MS determination. Linear relationships between values of peak area and mass fraction of the 31 pesticides were obtained in definite ranges, with detection limits (3S/N) ranged from 0.04 to 20 μg·kg-1. Recovery was tested, giving values of recovery in the range of 73.6% to 119%, with RSD′s (n=6) ranged from 0.70% to 17%.