Multiresidue screening of pesticides in foods using retention time locking, GC-AED, database search, and GC/MS identification

Fruit and vegetable extracts were screened for over 400 pesticides by gas c hromatography with atomic emission detection (GC-AED) and an experimental d atabase. A technique called retention time locking was used to match GC-AED and GC with mass spectrometry (MS) retention times to those of the databas e. Samples were analyzed for sulfur, nitrogen, phosphorus, and chlorine by GC-AED. Possible pesticides were suggested by database search and identifie d by GC/MS, Forty-four pesticide standards were analyzed to determine the p recision of retention time matching and the accuracy of the database search . Analytical retention times matched database retention times within 0.32 m in. Using elemental criteria, the database search identified the correct co mpound for 41 of 44 pesticide standards. For blind spikes of fruit and vege table extracts, the database suggested 22 of 26 spiked pesticides as matche s. Nineteen were identified by GC/MS, The combination of retention time loc king, GC-AED, database search, and GC/MS can be a powerful tool for identif ying pesticides in a complex matrix.