PRESSURIZED-LIQUID EXTRACTION FOR DETERMINATION OF IMIDAZOLINONE HERBICIDES IN SOIL

A rapid and simple method has been developed for determination of imidazolinone (IMI) residues in soil. Extraction of the analytes from the soil matrix was performed with a pressurized-liquid-extraction apparatus built in this laboratory. Four different types of soil sample (clay, clay loam, sandy clay loam, and silty loam) were fortified with target compounds at levels of 10 and 50 ng g-1 by a procedure which can mimic weathered soils. The samples were then dried and packed in a 25 cm × 4.6 mm i. d. stainless steel column; this was placed inside a GC oven and extracted by passing an aqueous solution of KCl (0.1 M, 20 mL) through the column at 90°C. Quantification of the analytes in the final extract (50-μL injection) was performed by reversed-phase liquid chromatography-mass spectrometry with a TurbolonSpray interface. Recoveries of the analytes were greater than 83% and RSD less than 7%. The method detection limit was in the 1 - 2.5 ng g-1 range in analysis by time-scheduled selected-ion monitoring (SIM).