Integrated pulsed amperometric detection of glufosinate, bialaphos and glyphosate at gold electrodes in anion-exchange chromatography

A rapid and practical method for direct detection of the herbicides (glufosinate, bialaphos and glyphosate) in anion-exchange chromatography has been developed with integrated pulsed amperometric detection (IPAD). The electrochemical behavior of these herbicides showed catalytic currents based on the oxidation of amines in their structures. Waveform in IPAD was similar to that for amino acids, which exhibited adsorption/desorption catalytic features at gold electrode surface in alkaline solution. Under optimized conditions, detection limits (signal-to-noise ratio of 3) for glufosinate, bialaphos and glyphosate were 20, 65 and 50 ng ml(-1), respectively, with correlation coefficients of 0.995, 0.997 and 0.996 over concentration ranges of 0.1-45, 0.3-32 and 0.1-50 mug ml(-1), respectively. The relative standard deviations (n=5) were 1.7-3.0%. The present method was successfully applied to the determination of glyphosate in urine and serum. (C) 2001 Elsevier Science B.V; All rights reserved.