Degradation study of benomyl and carbendazim in water by liquid chromatography and multivariate curve resolution methods

The degradation of benomyl and carbendazim in different organic solvents, distilled and ground waters was studied by on-line solid-phase extraction (SPE) followed by liquid chromatography (LC), diode array detection (DAD) or atmospheric pressure chemical-ionization mass spectrometry detection (APCI-MS), UV spectrophotometry and multivariate curve resolution. Stability studies were performed in different organic solvents, such as acetonitrile and methanol, and in aqueous solution at different pH. Samples were stored in dark conditions at 4 degrees C and analysed by LC-DAD over 10 days. Photodegradation products of benomyl were resolved by spectrophotometry and multivariate curve resolution between pH 3 to 9. These results were correlated with those from LC-DAD and LC-APCI-MS. Photolysis studies were carried out at low concentration levels (2 mu g L-1) of carbendazim under different storage conditions in order to evaluate the effect of parameters, such as pH, temperature and sunlight exposure. Water samples (50 mL) were preconcentrated using on-line SPE-LC-DAD. Photodegradation products of benomyl and carbendazim were identified by on-line-SPE-LC-DAD and SPE-LC-APCI-MS, leading to identification of carbendazim, 3-butyl-2,4-dioxo-s-triazino1,2-abenzimidazole (STB) and 2-aminobenzimidazole (2-AB).