USE OF HEXANE FOR THE QUANTITATIVE RECOVERY OF ORGANOPHOSPHORUS PESTICIDES FROM AQUEOUS-SOLUTION - FIELD METHOD AND A PRESERVATION TECHNIQUE

A general method for extraction, preservation and analysis of aqueous solutions containing traces of organophosphorus pesticides has been developed. Samples of water (natural and distilled) were extracted by high-speed stirring after addition of a small volume of hexane to the sample. Extracts of lower concentration were concentrated by evaporation prior to analysis by flame photometric gas chromatography to yield a detection limit of 1 ppb in most instances. Extraction by this method has been successful for 13 of the 16 organophosphorus pesticides used in this study with an efficiency of better than 95% under the experimental conditions described. The extracts from all aqueous solutions were found to be relatively stable for 45 days. Recent developments in the preservation techniques are compared with ours and the advantages of all techniques are discussed. © 1979.