Studies on the Stability of Organophosphorus Pesticides Part I

Estimation of Stability of Organophosphorus Pesticide Dust Formulation by Thermally Accelerated Degradation Test

Abstract

Some investigations on the accelerated degradation test of the organophosphorus pesticide dust formulations with elevated temperature were carried out. The methyl parathion and the malathion dust, which were formulated with Zeeklite (Commercial name of clay mineral), were stored for 24_??_116 days at 30°_??_70°C and room temperature. After accelerated test, the residual active ingredients were analyzed and the degradation rate was calculated. The degradation rates of the dusts at various temperatures were fitted to Jander's rate equation, when the degradation rate did not yet proceed to 80%.
Jander's rate equation: {1-(1-α)^1/3}²=kt
ex. α: reaction rate, k: degradation rate constant, t: reaction time.
Arrhenius' relationships were established between the degradation rate constants and the temperatures, and that the degradation rates of both dusts at the room temperature, which were estimated by Arrhenius' equation, were in good agreement with the experimental results.