SIMULTANEOUS DETERMINATION OF IMIDAZOLINONE HERBICIDES FROM SOIL AND NATURAL-WATERS USING SOIL COLUMN EXTRACTION AND OFF-LINE SOLID-PHASE EXTRACTION FOLLOWED BY LIQUID-CHROMATOGRAPHY WITH UV DETECTION OR LIQUID-CHROMATOGRAPHY ELECTROSPRAY MASS-SPECTROSCOPY

This paper describes the simultaneous quantification of the imidazolin one herbicides (IMIs) imazapyr, m-imazamethabenz, p-imazamethabenz, m, p-imazamethabenzmethyl, imazethapyr, and imazaquin in two types of sam ples, (a) Groundwater, lake water, and river water samples were enrich ed by off-line solid-phase extraction with a Carbograph-1 cartridge an d analyzed by reversed-phase liquid chromatography using a UV detector (lambda, = 240 nm). The overall recoveries of IMIs extracted from 1 L of groundwater (fortified with 500-100 ng/L), 0.5 L of lake water (fo rtified with 500-100ng/L), and 0.5 L of liver water (fortified with 10 00-200 ng/L) samples were not lower than 89%, The mean relative standa rd deviation (RSD) was 5.1% (ranging from 4.1% to 6.8%) in natural wat er, The detection limits were 30-39 ng/L in groundwater, 43-51 ng/L in lake water, and 55-67 ng/L in river water, The method involves confir matory analysis by LC/ES-MS in full-scan mode, The dependence of the i on signal intensities on proton concentration in the mobile phase was investigated with a view to optimizing the sensitivity of the ES-MS de tector, When LC/ES-MS was used, the limit of detection, calculated fro m extracted-ion current profiles (EICPs), was 4-7 ng/L for groundwater and 9-13 ng/L for river water, (b) Soil sample analysis utilized comb ined soil column extraction (SCE) and off-line solid phase extraction (SPE) for sample preparation, analyzing with LC/ES-MS under selected i on monitoring (SIM), Several different extractants were evaluated for the purpose of SCE optimization, The system that best optimizes the ex tractability IMIs from the soil was found to be the mixture CH3OH/(NH4 )(2)CO3 (0.1 M, 50:50 v/v), The effect of IMI concentration in the mat rix on recovery was evaluated, The total recovery of each IMI from soi l at each of the two levels investigated ranged from 87% to 95%, Under three ion SIM conditions, the limit of detection (S/N = 3) was 0.1-0. 05 ng/g in soil samples.