Chapter 71 - Multiresidue Analysis of Low- and Medium-polarity Pesticides in Olive Oil by GC-MS/MS

Abstract

Analytical methods for determining pesticides in fats and oils almost invariably require extraction of pesticide residues and fat from the matrix, followed by clean-up of the extract prior to chromatographic analysis. The most widely used technique in this context is liquid–liquid partitioning; however, other, more environmentally friendly methods such as supercritical fluid extraction with carbon dioxide are gradually gaining ground for this purpose. Extracts are usually cleaned up by passage through Florisil, alumina, or silica columns; matrix solid-phase dispersion; solid-phase extraction; or gel-permeation chromatography, GPC. Finally, as done for pesticides in other matrixes, identification and determination are performed with gas. On some occasions both liquid and gas chromatographies are coupled using the through oven transfer adsorption desorption (TOTAD) interface, and pesticides are detected by electron-capture and nitrogen-phosphorus detectors. Because of the large variety of pesticides used, the trace analysis of these compounds requires the development of multiresidue methods for the determination of the greatest number of compounds possible, with the fewest number of extraction and clean-up steps. The US Environmental Protection Agency (EPA) recommends the use of analytical methods where identification is confirmed by mass spectrometry (MS). This chapter describes a multiresidue method for analysis of residues of ca. 220 low- and medium-polarity pesticides in olive oil using GC-MS/MS.