Direct methylation at the surface of Carbopack B Part I: Determination of phenolic pesticides

Abstract

 A procedure for the determination of phenolic pesticides, i.e. the hydroxybenzonitriles bromoxynil and ioxynil and the 2,4-dinitrophenol-derivatives dinoseb, dinosebacetate, dinoterb, dinoterbacetate, dinobuton, binapacryl and DNOC is presented. The herbicides with a free phenolic OH-group as well as the corresponding esters are very strongly adsorbed on Carbopack B, a special graphitized carbon black. In contrast to the esters, which can be removed almost quantitatively, the substances with a free phenolic OH-group cannot be eluted in any significant amount. This effect was used for the derivatization of the herbicides directly on Carbopack B, using diazomethane or TMSH as reagents. The derivatives were eluted with ethylacetate and identified and quantified by GC/MS.

For recovery studies, water samples were spiked with the pesticides in concentrations within the range tolerated by the European Drinking Water Guideline.