Pressurized-liquid extraction for determination of imidazolinone herbicides in soil

A rapid and simple method has been developed for determination of imidazoli none (IMI) residues in soil. Extraction of the analytes from the soil matrix was performed with a pressu rized-liquid-extraction apparatus built in this laboratory Four different t ypes of soil sample (clay, clay loom, sandy clay loam, and silty loam) were fortified with target compounds at levels of 10 and 50 ng g(-1) by a proce dure which can mimic weathered soils. The samples were then dried and packe d in a 25 cm x 4.6 mm i. d. stainless steel column; this was placed inside a GC oven and extracted by passing an aqueous solution of KCI (0.1 M, 20 mL ) through the column at 90 degreesC. Quantification of the analytes in the final extract (50-muL injection) was performed by reversed-phase liquid chr omatography-mass spectrometry with a TurbolonSpray interface. Recoveries of the analytes were greater than 83% and RSD less than 7%. The method detect ion limit was in the 1 - 2.5 ng g(-1) range in analysis by time-scheduled s elected-ion monitoring (SIM).