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A technique for the analysis of aldicarb and two of Its degradation products Is described. The use of a short capillary column coupled to a mass spectrometer Is found to facilitate the analysis of the thermally labile carbamate pesticide. Methane and Isobutane chemical Ionization reagent gases are evaluated. The limits of detection for aldicarb, aldicarb oxime, and aldicarb nitrile are 0.3 ng, 1.2 ng, and 0.15 ng, respectively. Application of the technique to the study of the fate of aldicarb In anaerobic groundwaters Is described. Aldicarb Is found to slowly hydrolyze to aldicarb oxime In sterile anaerobic groundwater at pH 8.2; In the presence of a high concentration of anaerobic microorganisms, however, aldicarb rapidly degrades to aldicarb nitrile.

The reaction of aqueous free chlorine with three phenolic acids was examined before and after adsorption on granular activated carbon. Organic products were extracted from aqueous solution and off the carbon surface and analyzed by using gas chromatography/mass spectrometry. Complex reaction products and incomplete separations warranted the selection of a single compound, vanillic acid, for further study. Many products were formed on the carbon that were not present in the influent to the column. These products included several polyphenols and hydroxylated quinones that were tentatively identified from their methylated and silylated derivatives. The environmental significance of these reactions is discussed.