CIPAC Collaborative Study of the Heat-Stability of Diazinon Formulations, Using Both CIPAC and AOAC Analytical Methods

Abstract

Abstract Diazinon (O,O-diethyl O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate) and 3 different Diazinon formulations were analyzed both by the official CIPAC titrimetric method and by the AOAC official first action gas chromatographic method. In addition, all samples were subjected to the CIPAC accelerated storage test by heating (2 weeks at 54°C) and analyzed by the 2 methods before and after storage. Eight collaborators from European countries and the United States took part in the study. Analytical results were reproducible within and between laboratories by both methods. As demonstrated by an analysis of variance, the 2 procedures yielded identical results. Therefore, both the CIPAC and the AOAC methods may be considered as equivalent with good accuracy and reproducibility. After storage at 54°C for 14 days only one Diazinon dust formulation revealed a significant decrease in Diazinon content as shown by a t-test.