DIRECT METHYLATION AT THE SURFACE OF CARBOPACK-B .1. DETERMINATION OFPHENOLIC PESTICIDES

A procedure for the determination of phenolic pesticides, i.e. the hyd roxybenzonitriles bromoxynil and ioxynil and the 2,4-dinitrophenol-der ivatives dinoseb, dinosebacetate, dinoterb, dinoterbacetate, dinobuton , binapacryl and DNOC is presented. The herbicides with a free phenoli c OH-group as well as the corresponding esters are very strongly adsor bed on Carbopack B, a special graphitized carbon black. In contrast to the esters, which can be removed almost quantitatively, the substance s with a free phenolic OH-group cannot be eluted in any significant am ount. This effect was used for the derivatization of the herbicides di rectly on Carbopack B, using diazomethane or TMSH as reagents. The der ivatives were eluted with ethylacetate and identified and quantified b y GC/MS. For recovery studies, water samples were spiked with the pest icides in concentrations within the range tolerated by the European Dr inking Water Guideline.