EXTRACTION OF ATRAZINE, CYANAZINE, DESETHYLATRAZINE, DESISOPROPYLATRAZINE, AND METOLACHLOR FROM FORTIFIED WESTERN CORN-BELT SOILS BY SFE WITH CO2

Supercritical fluid extraction (SFE) using CO2 has been demonstrated a s an alternative to polar organic solvents or water for the quantitati ve removal of atrazine, two of its metabolites, cyanazine, and metolac hlor for several agricultural soils. Recoveries of each analyte from s oil fortified from 0.1 to 2.0 mg/kg ranged between 25 and 120%, depend ing upon the soil matrix and analyte extracted. A single extraction, u sing cosolvent-modified CO2, conducted at relatively high fluid densit y in both static and dynamic modes, sufficed for all analytes. Princip al component analysis was used to correlate each component in a matrix of dependent variables influencing extraction efficiency. HPLC analys is indicated that fewer coextracted moieties are found using SFE rathe r than from extractions using polar liquid solvents. Addition of both water and methanol to the air-dried soil prior to commencement of CO2 flow does enhance the recovery for all analytes. Further, such cosolve nts do not promote the conversion of the chloro-triazine analytes to a ny of their corresponding hydroxy or methoxy analogs under the SFE con ditions tested.