Screening of Agricultural Products for Pesticide Residues using GCMS-QP2010 in Full-Scan Mode, GCMSsolution software and Shimadzu Pesticides Mass Spectral Library

Introduction

GCMS is commonly used for screening of agricultural products for the presence of pesticide residues. This is due to the ability of GCMS to separate the pesticide residues from the other compounds in the agricultural products, and to give mass spectra of the pesticides for confirming the identity of the pesticides. For this purpose, the ionization mode of the GCMS is usually set to Electron impact Ionization, and the acquisition mode is set to Full Scan. Electron impact Ionization (El) combined with Full Scan acquisition is good for identification of a compound because the ionization produces an extensive fragmentation for most organic compounds, which in turn gives a characteristic mass spectrum for the compound analyzed. However, the extensive fragmentation in El mode and the complexity of the sample matrix (that is, the presence of many other compounds in the vegetable samples) also result in a GCMS chromatogram which can easily contain more than 100 peaks. Finding the pesticides peaks in such a chromatogram can be a tedious task if we have to analyze the mass spectra one by one. Especially when the target peaks are much smaller than the interference peaks. GCMSsolution software (Ver. 2) offers a solution to the problem through its Compound Finder feature. An example of the application of Compound Finder is illustrated in this report.

August 10, 2006 GMT