A simple and rapid spectrophotometric method to quantify the herbicide glyphosate in aqueous media. Application to adsorption isotherms on soils and goethite

CAROLINA V. WAIMAN; MARCELO J. AVENA; MARIANO GARRIDO; BEATRIZ FERNANDEZ BAND; GRACIELA P. ZANINI

GEODERMA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 170 p. 154 - 158

0016-7061

This article presents a simple, fast and low cost UV–vis spectrophotometric method to quantify glyphosate. This method can be used to perform adsorption isotherms on soils and metal oxides. It comprises a derivati- zation step and further measurement of the absorbance at 265 nm. The trueness of the results is validated using Ultra Performance Liquid Chromatography with tandem mass spectrometry detection (UPLC-MS/MS) as a reference method. The proposed spectrophotometric method is able to quantify glyphosate in the con- centration range from 0.084 to 21.8 mg L− 1 . This range is suitable to construct reliable adsorption isotherms. Examples of adsorption isotherms on goethite at pH 4.5 and a soil sample at pH 4.5, 6.0 and 8.0 are given. Interferences caused by dissolved organic matter can be corrected at least up to an organic matter concentra- tion of 12 mg L− 1 .