Supercritical fluid extraction from soil and HPLC analysis of cyanazine herbicide.

摘要

The efficacy of supercritical fluid extraction (SFE) for the recovery of cyanazine 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 14C-ring-labelled and non-labelled 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 50deg C was optimal. With 6 and 20 minute static and dynamic extraction times, respectively, cyanazine could be extracted from soil in 40-45 minutes. 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.