Supercritical fluid extraction of triazine herbicides from solid matrices

Several investigations were performed to optimise the extraction of polar triazine herbicides using supercritical fluid extraction from two different solid matrices: C18-silica and soil samples. Supercritical CO2 modified with methanol [10% (V∶V)] at 250 bars and 50°C was required to quantitatively extract Atrazine and 2-Hydroxyatrazine from spiked C18-silica. Extraction of Desisopropyl-desethyl-2-hydroxyatrazine (MET) attained only 52%, even following addition of water to the polar modifier. Extractions of spiked soil samples (20 ppm of each pesticide) were successful at 300 bars and 65°C. A non polar wash improved the recoveries of the three target analytes [i.e. atrazine: 88%; 2-hydroxyatrazine: 96%; MET: 41%]. The extraction parameters employed are discussed in this paper.