Phototransformation of herbicide metsulfuron methyl

Abstract

Phototransformation of the herbicide metsulfuron methyl was investigated on glass surface under sunlight and ultraviolet (UV) light and compared with dark condition. The half-lives of metsulfuron methyl under UV light and sunlight were found to be 0.5 and 7.8 days respectively. Rate of phototransformation followed first order kinetics with significant correlation coefficient. The major photoproducts were identified as methyl-2-sulfonyl-amino-benzoate, 2-amino-6-methoxy-4-methyltriazine and saccharin (O-sulfobenzoimide). Various metabolites from this study were identified by high performance liquid chromatography (HPLC). Authentic samples required for HPLC comparison were prepared in laboratory and characterized on the basis of nuclear magnetic resonance (NMR) and infra red (IR) spectral data. These metabolites were also identified from metsulfuron methyl treated wheat field soil.

Keywords:

• Phototransformation
• metsulfuron methyl
• herbicide
• UV light
• sunlight

Acknowledgments

One of the authors Rupak Paul gratefully acknowledges the financial assistance provided by Indian Council of Agricultural Research, New Delhi. Divisional contribution no. 960.

Notes

* Solvent system – chloroform:methanol (95:5).

*Average of three replicates; SD-standard deviation, figure in parenthesis indicates % dissipation of metsulfuron methyl.