Optimization of an Enrichment and LC-MS/MS Method for the Analysis ofGlyphosate and Aminomethylphosphonic Acid (AMPA) in Saline NaturalWater Samples without Derivatization

摘要

Glyphosate represents the main ingredient of commercially available total-herbicides such as Roundup?, which is frequently applied in agricultural? areas. Leaching of the herbicide to rivers also results in its transport to the estuarine and coastal environment. The analysis of low concentrations of glyphosate (μg/L range) in sea water samples is a challenge due to the high salinity as well as the overall complex matrix composition of such samples. To overcome these difficulties an optimized two-step method for the enrichment of glyphosate and its main degradation product aminomethylphosphonic acid (AMPA) from saline natural water samples using an ion exchange based procedure is presented in this study. The determination of both analytes was performed using an optimized LC-MS/ MS MRM method, which does not require any derivatization of the analytes. The optimized method was further characterized in terms of achievable LODs and LOQs, robustness and repeatability. The achievable enrichment factor dependent on the sample volume was investigated. Finally, the developed method was applied for the analysis of samples from the tidal influenced Elbe region between Hamburg and the Elbe estuary near Cuxhaven. While the glyphosate concentrations determined in the different samples were below the LOQ, AMPA concentrations at almost all sites were above the method′s limit of quantification (6 μg/L) indicating a decreasing gradient from the Hamburg area to the estuary region.