SUPERCRITICAL CO2 FLUID EXTRACTION OF IMAZAQUIN FROM SOIL

Feasibility of supercritical CO2 fluid extraction of imazaquin from spiked soil (3.21 mumol kg-1) as an alternative to a conventional extraction method was investigated. The supercritical fluid extraction method involved single-step extraction of herbicide from soil with no further sample cleanup procedures. Extraction parameters were optimized for maximum herbicide recovery. Adding water as a modifier to air-dried soil significantly improved herbicide recovery. Extracting a 1-g soil sample with supercritical CO2 at 0.80 g ml-1 density and 3 ml min-1 flow rate, 80 C extraction temperature, 6 min static extraction followed by 25 min dynamic extraction, and analyte trap temperature of 40 C was optimum for maximum herbicide recovery. When optimum supercritical fluid extraction conditions were used, imazaquin recovery from three texturally different soils ranged from 55 to 64%, which was comparable to a conventional extraction method (63%). The supercritical fluid extraction method consumed 4 ml methanol and 75 ml supercritical CO2 and took approximately 1 h for sample extraction.