Dissipation of sulfosulfuron in water – Bioaccumulation of residues in fish – LC-MS/MS-ESI identification and quantification of metabolites Original Research Article

Dissipation study of sulfosulfuron in natural water and its bioaccumulation in fish was conducted at 25 ± 2 °C and at two different concentration levels 1 mg l−1 and 2 mg l−1. The dissipation data in water showed the DT50 and DT90 values 67–76 and 222–253 days and followed first order kinetics. Bioaccumulation of sulfosulfuron in fish was conducted under static conditions exposing the fish at one-tenth of sub-lethal concentration 9 mg l−1 and at double the concentration 18 mg l−1, for a period of 56 days. On different occasions fish samples were collected and analyzed. A HPLC-RF method was used for the quantification of sulfosulfuron and aminopyrimidine with the limit of quantification 0.001 μg ml−1. Results showed the accumulation of residues of sulfosulfuron in fish over the concentration range 0.009–0.496 μg g−1. Both in water and fish samples, identified the presence of metabolites aminopyrimidine, desmethyl sulfosulfuron, guanidine, sulfonamide, ethyl sulfone and rearranged amine. The formations of these metabolites are confirmed by LC-MS/MS analysis. An LC-MS/MS electro spray ionization technique was used for this purpose. One of the metabolite Aminopyrimidine was identified at higher concentration levels (0.01–0.1 μg ml−1) when compared with other metabolites. Subsequently dissipation of aminopyrimidine in water and its bioaccumulation was also studied at the concentration level 1 mg l−1 and 2 mg l−1. The calculated DT50 and DT90 values are 66–68 days and 218–226 days, respectively. This followed first order kinetics. Three hundred days after the exposure complete demineralization was observed.