Supercritical fluid extraction from soil and HPLC analysis of cyanazine herbicide

Efficacy of supercritical fluid extraction (SFE) for the recovery of cyanazine (2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile) from soil was investigated. A reverse-phase HPLC method and a TLC method were developed for quantitative separation of cyanazine from its seven metabolites. Dundee silty clay loam soil treated with C-14-ring-labeled and nonlabeled cyanazine was used. Several SFE parameters were optimized for maximum recovery of cyanazine. Methanol/water (1:1) added directly to the soil matrix was the most efficient modifier. Extraction with supercritical CO2 at a flow rate of 3.0 mL min(-1), a density of 0.90 g mL(-1), and an extraction temperature of 50 degrees C was optimal. With 6 and 20 min static and dynamic extraction times, respectively, cyanazine could be extracted from soil in 40-45 min. With a considerable savings in time and lower waste solvent generation, recoveries (>90%) very similar to conventional extraction procedures could be obtained. Extraction of some of the cyanazine metabolites from soil, under the conditions optimized for cyanazine, was also investigated.