Determination of pesticides by derivative formation. Part IV. A sensitive gas-chromatographic method for the determination of MCPA and MCPB herbicides after esterification with 1-bromomethyl-2,3,4,5,6-pentafluorobenzene

Abstract

A sensitive quantitative method for the gas-chromatographic determination of 4-chloro-2-methylphenoxyacetic acid (MCPA) and 4-(4-chloro-2-methylphenoxy)butyric acid (MCPB) in natural water is presented. The 2,3,4,5,6-pentafluorobenzyl (PFB) esters of MCPA and MCPB have longer retention times and provide increased sensitivity over the conventional methyl and 2-chloroethyl esters of these acids. Concentrations as low as 0.1 µg l^–1 of MCPA and 0.2 µg l^–1 of MCPB (for a 1-l water sample) can be determined by this method.