DETERMINATION OF GLYPHOSATE AND ITS MAJOR METABOLITE AMINOMETHYLPHOSPHONIC ACID BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AFTER DERIVATIZATION WITH PARA-TOLUENESULFONYL CHLORIDE

A high-performance liquid chromatographic procedure is described for the simultaneous determination of glyphosate and its major metabolite aminomethylphosphonic acid (AMPA). Glyphosate and AMPA were derivatized with p-toluenesulfonyl chloride under alkaline conditions and an aliquot of the reaction mixture was injected into a C18-5 column with a mobile phase consisting of 0.2 M phospate buffer (pH 2.30)-acetonitrile (85:15, v/v) and detection at 240 nm. The response was linear in the range 100 ng-4-mu-g/ml for both compounds in the sample solution and the minimal detectable quantities were 10 ng/ml of glyphosate and 8 ng/ml of AMPA with a 20-mu-l injection, respectively.