Abstract:

A reversed-phase high-performance liquid chromatographic (RP-HPLC) method was proposed for the determination of imazethapyr in soybeans and its reliability was evaluated by determining various figures of merit such as sensitivity, accuracy and precision. Samples were extracted using a mixture of methanol and 0.1 mol/L sodium carbonate aqueous solution with ultrasonic assistance and centrifugated. The supernatant was then harvested, acidified and extracted twice using methylene chloride. The methylene chloride phase was finally separated using a separatory funnel and cleaned up on a strong cation exchange solid-phase extraction column and the resulting eluate was evaporated to dryness and redissolved in methanol prior to injection into the HPLC system equipped with a UV detector. The method revealed a limit of detection of 0.00837 mg/kg. Mean recoveries of 3 replicates for imazethapyr in 4 varieties of soybeans spiked at 3 levels were within the range of 70.6%－106.7%, with a RSD range of 1.56%－12.8%. This method proved to meet the Chinese national standard requirements for the determination of pesticide residue in foods.

Key words: imazethapyr, high performance liquid chromatograghy, residue, bean