Chapter 23 Pesticides

Abstract

Publisher Summary The chapter describes pesticides and several important techniques and applications of chromatography to the determination of pesticides residues. Pesticides are a very diverse group of compounds that can be classified according to their intended use as insecticides, fungicides, herbicides and plant growth regulators, rodenticides, miticides, and nematocides. They can be classified additionally according to their chemical structures: organochlorine (OC) insecticides, organophosphorus (OP) insecticides, pyrethroid insecticides, substituted chlorophenoxy acid or ester herbicides, carbamate insecticides, herbicides and fungicides, urea herbicides, triazine herbicides, and other miscellaneous types, including uracils, chlorinated phenols, organo-mercury and -tin compounds. Pesticide analysis is broadly divided into formulation and residue analysis. Residue analysis involves the determination of parts-per-million (ppm), -billion (ppb), or -trillion (ppt) of pesticides and/or their metabolites and degradation products. Chromatography is utilized for the clean-up, determination, and confirmation of pesticide residues. The term “sample preparation” is sometimes used to indicate the steps required to prepare the sample for extraction. Simultaneous extraction and clean-up has been carried out in a chromatographic column. Capillary-column (high-resolution) gas chromatography (GC) is being applied to an increasing degree for separations of complex mixtures and GC/MS confirmations. Manual and automatic injection has been used in split, splitless, and on-column modes. The major pesticide GC detectors for packed and capillary columns are the ECD, nitrogen/phosphorus (NPD), alkali-flame ionization (AFID), thermionic (TID), flamephotometric (FPD), and Hall electrolytic conductivity (HECD) detectors. Currently, GC is the major chromatographic method used for pesticide residue analysis; however, applications of HPLC, HPTLC, and SFC have been also increasing steadily.