Extraction of atrazine and its metabolites using supercritical fluids and enhanced-fluidity liquids
Supercritical fluid and enhanced-fluidity liquid extractions are performed on spiked sediment samples containing atrazine (ATRA) and five of its metabolites including desisopropyldesethylatrazine, desethylhydroxyatrazine (DEHA), desisopropylatrazine, desethylatrazine, and hydroxyatrazine (HA). The hydroxylated metabolites are of particular interest because of their increased water solubility and the fact that their high polarity makes them difficult to analyze. Soxhlet extractions using methanol are conducted for the purpose of comparison. Results of the extractions show that the hydroxy-containing metabolites of ATRA are not effectively extracted with supercritical CO2 alone. The solvating or desorbing power of carbon dioxide appears too low to extract HA and DEHA. The extraction recoveries of the hydroxylated metabolites increase when enhanced-fluidity liquid mixtures of methanol/CO2 are used, and these rates increase with the methanol concentration. Enhanced-fluidity ternary liquid mixtures of H2O/methanol/CO2 yield the best recoveries for these compounds. ATRA recoveries are equally effective when using supercritical CO2 or enhanced-fluidity mixtures. The other nonhydroxy-containing metabolites require the increased solvent strength of either large percentages of methanol in CO2 or ternary mixtures of H2O, methanol, and CO2 for high recoveries. Recoveries with enhanced-fluidity liquid ternary mixtures are better than the recoveries from Soxhlet for all the compounds in the study.
Shows
ME
Department of Chemistry and Environmental Science Program, The Ohio State University, Columbus 43210, USA.
Olesik
SV