Photodegradation of the carbamate pesticides aldicarb, carbaryl and carbofuran in water

Abstract

The photodegradation of the pesticides aldicarb, carbofuran and carbaryl. in distilled, pond and artificial sea-water samples with or without humic acids was examined. In addition, two different light sources, a xenon arc lamp and a high-pressure mercury lamp, were used to compare the photolysis behaviour. The effect of temperature on hydrolysis was also studied. The major photodegradation products were identified by matching their diode-array spectra with the corresponding spectra of the authentic standards, using peak purity software of the diode array and their retention times. Aldicarb sulphoxide was the major photodegradation product from aldicarb whereas 1-naphthol was the main hydrolysis product from carbaryl. Acetone (5%) was added as a photosensitizer in this instance. For carbofuran, one main unidentified hydrolysis product was detected. Analyses were made by direct injection of water samples into a liquid chromatograph with diode-array detection.