Selective analysis of the herbicides glyphosate and aminomethylphosphonic acid in water by on-line solid-phase extraction high-performance liquid chromatography electrospray ionization mass spectrometry

A fully automated on-line solid-phase extraction-high-performance liquid chromatography-electrospray ionization mass spectrometry (SPE-HPLC-ESI-MS-MS) method was developed for the determination of glyphosate and its degradation product aminomethylphosphonic acid (AMPA), in the concentration range of 0.05 to 3 mu g/l in various types of water. Derivatisation of glyphosate and AMPA directly in the native aqueous sample with 9-fluorenyl methoxycarbonyl chloride allowed the preconcentration by SPE and HPLC separation. Identification and quantification based on the constant ratio of three selected ions for each compound (precursor ion and two product-ions) together with the retention time proved to be a very selective procedure for the reliable determination of these pesticides. Although developed for drinking water and surface water, the selectivity of this method also allows their determination in waste water. Moreover, the structurally similar herbicide glufosinate could also be determined using the same derivatisation procedure and analytical method. Validation of the HPLC-MS method for glyphosate and AMPA showed detection limits as low as 0.03 mu g/l. Recoveries of 96% and relative standard deviations for repeatability <8.4% were determined at 0.2 concentration. (C) 1998 Elsevier Science B.V.