In vitro dissipation of S-metolachlor herbicide in different pH water

Abstract

In vitro dissipation of S-metolachlor was studied in neutral, acidic and basic water at 0.2 – 0.4 µg/g (T1) and 0.4 - 0.8 µg/g (T2) levels of fortification at All India Network Project on Pesticide Residues, ICAR, Unit-9, Anand Agricultural University, Anand (Gujarat), India. The S-metolachlor dissipated much rapidly in acidic and basic water as compared to neutral. Between the acidic and basic water, the rate of degradation was comparatively faster in basic water. In all the three pH water, the degradation followed first order kinetic with mono and biphasic mode. The herbicide underwent degradation at much faster rate in acidic and basic waters as the residue reached below determination level (BDL) of 0.05 µg mL-1 with half-life values ranging from 1.8 to 12.5 day and 12.04 to 301.0 day for Phase-I and Phase-II, respectively. However, in neutral water the rate of degradation was much slower and the residues reached below determination level on the 60th day with half-life ranging 3.4 to 12.5 and 100.3 to 300.1 days for Phase-I and Phase-II, respectively.