Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 24, 1996
Publication Date: N/A
Technical Abstract: Imazethapyr, an imidazolinone (IMI) herbicide, is used to control grasses and broadleaf weeds in soybeans. Nicosulfuron, a sulfonylurea (SU) herbicide, is used to control grasses in corn. Both are extracted simultaneously from acidified water on 1000-mg cyclohexyl cartridges and separated on a C18 LC column chemically shielded to enhance separations of organic bases. Resolution is achieved through tertiary acetonitrile-water gradients at pH 7.0 and 3.0 in order to isolate the analyte peaks from each other and from co-extracted herbicide-derived chemicals. Detection of both analytes is by photodiode-array simultaneously at 254, 220, and 199 nm. Two-liter water samples are reduced to a 1.0 mL final volume in initial-conditions mobile-phase. A 250-uL injection volume furnishes a nominal detection limit of 5 ug L**-1. Quantitation is via external-standard multi-point calibration. Confirmation of identity is by HPLC-MS. Method validation is achieved through spike-recovery studies.