Determination of glyphosate and its metabolite, (aminomethyl)phosphonic acid, in serum using capillary electrophoresis.

Capillary electrophoresis has been used to separate and quantitate glyphosate and its major metabolite, (aminomethyl)phosphonic acid (AMPA), in serum. The two compounds, after derivatization with p-toluenesulphonyl chloride, were clearly separated with 0.1 M boric acid-sodium hydroxide buffer (pH 9.6) containing 10% methanol. The separation was completed within 15 min at an applied potential of 30 kV. Calibration curves for the assay were linear over both the lower (0.5-10 micrograms/ml) and the higher (10-100 micrograms/ml) concentration ranges. The within-run and day-to-day coefficients of variation of peak area were 1.4-4.4 and 4.4-8.5%, respectively, for glyphosate and 1.8-2.9 and 1.8-2.9%, respectively, for AMPA. The within-run and day-to-day precisions of the migration time for both compounds were less than 1.8% and less than 2.5%, respectively. The detection limit of both derivatives was 0.1 microgram/ml in spiked sera, and the recoveries of glyphosate and AMPA were 87.9-88.8 and 78.4-86.9%, respectively. In this study, the reproducibility and the effect of pH changes on the electropherograms were especially examined.