IMPROVED METHOD FOR THE ANALYSIS OF IMAZAPYR IN SOIL

A method for the analysis of imazapyr opropyl-4-methyl-5-oxo-2-imidazo lin-2-yl)nicotinic acid] residues in tropical and temperate soils was developed. Imazapyr residues, extracted from soil with ammonium hydrog en carbonate and cleaned-up by centrifuging, anion-exchange solid-phas e extraction (SPE), pH adjustment, and C-18 SPE, were determined by HP LC. Recoveries from soils from Hawaii (Halii sandy clay loam), Texas ( Houston Black clay), and Maryland (Codorus loam), USA, fortified with imazapyr (0-5 mu g g(-1) soil) and equilibrated for 12-18 h, were 99(/-3)%, 104(+/-4)% and 89(+/-2)%, respectively. Recoveries were indepen dent of fortification level, but dependent upon soil type. Methods pre viously described in the literature produced imazapyr recoveries of le ss than 60% with Halii soil. This improved method has a limit of detec tion of 5 ng g(-1) (equivalent to or better than other methods) and af fords higher recovery of imazapyr residues from tropical soil.