Residues of imazapyr are extracted from the finely ground samples of forest litter, pine twigs, or green leaves by shaking with an aqueous phosphate buffer. Methanol is added to the extract, and the solution is partitioned with methylene chloride as a preliminary cleanup. Residues of imazapyr are extracted from soil by shaking with 0.5N sodium hydroxide in water. The water method for determining residue levels is similar to the soil method in that imazapyr residues are extracted from water by using a CI8 solid-phase extraction cartridge and cleanup and additional specificity are obtained by using an SCX cartridge. Quantitation is accomplished by liquid chromatography and a UV detector. Residues of imazamethabenz-methyl are extracted from homogenized sunflower seed by boiling the seed with 0.5N sodium hydroxide, as previously described for wheat and barley. Half of the extract is concentrated on a rotary evaporator to a volume of 30 to 40 ml to remove the methanol.