Stopped-flow determination of carbaryl and its hydrolysis product in mixtures in environmental samples

A kinetic method for determination of carbaryl and its hydrolysis product in mixtures, by a modular stopped-flow system, is reported. The method involves the formation of the coupling product formed between 1-naphthol, the hydrolysis product of carbaryl and diazotized sulphanilic acid in a weak acid medium. With one hydrolysed and one unhydrolysed sample aliquot both carbaryl and 1-naphthol can be determined in their mixtures, with a relative standard deviation of 0.8%. The method is highly selective and free from interference by other pesticides tested and has been applied to the analysis of environmental samples for carbaryl and 1-naphthol.