Determination of the active-ingredient content of technical and formulated DNOC and dinoseb and technical dinobuton by spectrophotometry. A Collaborative International Pesticides Analytical Council study

Abstract

A spectrophotometric method is described for the determination of the activeingredient content of technical and formulated DNOC (2-methyl-4, 6-dinitrophenol) and dinoseb (2-sec-butyl-4, 6-dinitrophenol), and technical dinobuton (2-sec-butyl-4, 6-dinitrophenyl isopropyl carbonate). The method involves a preliminary clean-up on Woelm neutral alumina (grade I). Impurities are eluted from the column while the active ingredient is retained at the top of the column. The active ingredient is then eluted as its butylammonium salt and determined spectrophotometrically. Dinobuton samples require a preliminary separation from free dinoseb, de-esterification on the column and determination using the dinoseb procedure. Results obtained from international collaborative studies are presented and discussed.