DEVELOPMENT AND VALIDATION OF RESIDUE METHODS FOR THE DETERMINATION OF THE PYRETHROIDS LAMBDA-CYHALOTHRIN AND CYPERMETHRIN IN NATURAL-WATERS

This paper describes the development of methods suitable for the sampling and analysis of the pyrethroid insecticides lambda-cyhalothrin and cypermethrin in natural waters. A solid-phase water-sampling method which avoids the requirement for transport and storage of large volumes of water is described. This method is shown to be capable of extracting trace levels (ng litre-1) of the title compounds from natural waters with efficiencies of at least 80%. Chromatographic analysis of processed samples by gas chromatography-electron capture detection enables determination of residues at levels of 1-2 ng litre-1 in water.