Improved polarographic method for determination of glyphosate herbicide in crops, soil, and water.

A prior method for determination of glyphosate in water samples has been modified to accommodate samples of crops and soils. Differential pulse polarography as the determinative step enables analysis in an aqueous medium, which is important during extraction of this compound. Residues are cleaned up and concentrated by ion exchange on a strong basic resin in OH- form. The method is rapid, is applicable to a relatively broad selection of sample types, and gives recoveries consistently better than 60% with good precision. The main shortcoming of the method is that the limit of detection of 0.5-1.0 ppm may sometimes be inadequate. The metabolite, aminomethyl phosphonic acid, is not detected.