SELECTIVE ANALYSIS OF THE HERBICIDES GLYPHOSATE AND AMINOMETHYLPHOSPHONIC ACID IN WATER BY ONLINE SOLID-PHASE EXTRACTION HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

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