Determination of four imidazolinone herbicide residues insoils by solid-phase extraction-high performance liquid chromatography

A new method for determining residues of imazapyr, imazapic, imazamethabenz-methyl and imazethapyr in soil was developed by solid-phase extraction (SPE) cleanup and high performance liquid chromatography(HPLC) detection. Various extraction reagents, solvents at different pH values, various type of SPE and the elution volumes were compared. Extraction with V(acetonitrile):V(water)=5:3 at pH 3, with SAX cartridge SPE purification of the extracts were found to be the most suitable conditions. Determination was done with HPLC coupled with diode array detector(DAD). Mean recoveries of four imidazolinone herbicides at fortification levels of 0.02-0.5mg/kg were between 86%-109% (RSD≤3.3%, n=5). Under the optimal conditions, limits of quantification in soil were 0.01 mg/kg for imazapyr, imazapic and imazethapyr, and 0.02 mg/kg for imazamethabenz-methyl (S/N=3).