Multiresidue analysis of pesticides in vegetables by gas chromatography

Abstract

Pesticide multiresidue method for green pepper, lettuce, Chinese cabbage was developed. By examining of available multiresidue methods, 232 pesticides were selected for test. However, 199 compounds were used for the grouping of multiresidue test mixtures (MTRMs) after GC-MSD analysis. GC analysis conditions of Food Code were adapted for the study. MTRMs consisted of 10 groups of compounds (ECD 5 groups and NPD 5groups) based on retention time and responding detector. Total 18 compounds (11compounds for ECD and 7 compounds for NPD) of recovery test mixture (RTM) was also established based on the Log P and chemical classes. A new extraction solvent, and clean up eluant for SPE cartridge were established to develop two types of multiresidue methods (MRM I and MRM II). MRM II method gave better recovery from vegetables than MRM I method using RTM. Recovery test with MRTMs was conducted using MRM II, resulting in that seventy percents of compounds was recovered by 50~140%, while 9% of compounds were over 140% of recovery and only 7~8 compounds were not detected. Azoles showed relatively lower recovery rate compared to other chemical groups and as excepted, more polar compounds of Log P <1 gave low recovery rates than the group of higher Log P (>1)