Determination of glyphosate in the oxidation products of N -phoshonomethyl iminodiacetic acid by IR spectrometry

A method is developed for determining N-phosphonomethyl glycine (glyphosate) in the oxidation products of N-phosphonomethyl iminodiacetic acid (PMIDA) by IR spectrometry. In the IR spectra of glyphosate and PMIDA characteristic bands at 1562 and 721 cm−1, respectively, are revealed; based on absorbance at these wavelength, quantitative determination of glyphosate in the presence of PMIDA is possible. For model mixtures a correlation is revealed between the actual glyphosate concentration and the one derived from absorbance at characteristic bands. As shown, NMR (1H, 31P) and IR spectrometry yield comparable results. The method is verified by an analysis of the final product prepared by liquid-phase oxidation of PMIDA to glyphosate using hydrogen peroxide and may be utilized in quality control in its manufacture.