There are many obstacles in studying the environmental fate of glyphosate [N-(phosphonomethyl)glycine], an herbicide used to control the growth of weeds. Its negative contributions to the environment are, therefore, poorly understood.  In addition, the cost of monitoring the amount of glyphosate and its degradation product [aminomethylphosphonic acid (AMPA)] in surface waters can be cost prohibitive in terms of the analytical technique selected (e.g., LC-MS/MS), sample preparation, and number of samples to be tested.  This study describes research that utilizes a cost-effective flow-injection analysis system (FIA) that capitalizes on the phosphorus containing portion of glyphosate and AMPA molecules.  Orthophosphate can be generated from glyphosate in a photo-oxidation reactor with acid and an oxidant.  The produced orthophosphate then forms the antimony-phospho-molybdate complex, which is detectable via UV-Vis spectrophotometry (700 nm).  Optimized reaction conditions for the digestion of glyphosate to orthophosphate with persulfate and nitric acid, and the formation of the antimony-phospho-molybdate complex in the FIA system are presented.  Accuracy, precision, and limits of detection (LODs) between a standard Z-type flow cell (1.0-cm path length, SMA-Z; FIA Instruments) and a liquid waveguide capillary cell (1.0 m path length, 3000 Series, World Precision Instruments) are compared.

Study towards a cost-effective flow injection analysis (FIA) system for the quantification of glyphosate in surface water

247th National Meeting (2014)

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