DETERMINATION OF 9 ACIDIC HERBICIDES IN WATER AND SOIL BY GAS-CHROMATOGRAPHY USING AN ELECTRON-CAPTURE DETECTOR

Two simple and convenient methods are described for the extraction, analysis and clean-up of nine acidic herbicides in water and soil samples. The extracted acidic herbicides were converted into their methyl esters by a modified method using diazomethane. The methylated herbicides were analyzed by gas chromatography with electron-capture detection using a Restek Rt(x)-35 0.53 mm I.D. capillary column and simultaneously confirmed using an RT(x)-5 capillary column. A simple clean-up procedure using a micro disposable Florisil column is also described. The mean recoveries for all herbicides from water were > 95% and from soils > 86%. The recoveries of herbicides after Florisil column clean-up were greater than 89%. Each sample run required about 25 min, including confirmation. The methods described are suitable as an initial screening procedure in the rapid simultaneous determination of nine acidic herbicides in large numbers of environmental samples at reasonable cost.