Chemical Derivatization in Pesticide Analysis

Many approaches have been used in the identification and determination of pesticides at both the macro- (formulations) and micro- (residues) levels in various substrates. A number of the more commonly used methods of analysis are shown in Table 1 and the range of techniques used gives an indication of the difficulties encountered by the pesticide analyst. Traditionally, chemical derivatization has played an integral part in the analysis of pesticides since the widespread use of the organochlorine (OC) insecticides and herbicides in the 1940s. In 1955 Gunther and Blinn published Analysis of Insecticides and Acaracides, which gave detailed formulation and residue procedures for about 90 inorganic and organic compounds used in current pest control practices.(1) Of the 15 or so organochlorine insecticides discussed, many of the formulation procedures employed a total chlorine method while others utilized specific reactions to produce colored compounds. While DDT formulations could be determined via total chlorine, DDT residues were analyzed by the Schechter—Haller method involving nitration to a tetranitro derivative which produced a colored compound on treatment with alcoholic sodium methoxide.