Glyphosate - Determination of glyphosate and AMPA in urine by LC-MS/MS: Biomonitoring Method - Translation of the...

The working group "Analyses in Biological Materials" of the German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area developed and verified the presented biomonitoring method. The aim of this method is the selective and sensitive quantitation of glyphosate (N-phosphonomethylglycine) and its only metabolite, aminomethylphosphonic acid (AMPA), in urine. Samples undergo solid-phase extraction prior to liquid chromatography-tandem mass spectrometry using glyphosate-2-¹³C,¹⁵N and AMPA-¹³C,¹⁵N,D₂ as internal standards. Calibration is carried out with urine from persons with no known exposure to glyphosate and AMPA. The procedure has been comprehensively validated and the reliability data have been confirmed by replication and verification of the procedure in a second, independent laboratory. Good precision data with standard deviations of 1.3-9.8% for glyphosate and 1.9-5.4% for AMPA, as well as good accuracy data with mean relative recoveries in the range of 91-102% for glyphosate and 100-106% for AMPA, show that the method provides reliable and accurate analytical results. The method is both selective and sensitive, and the limits of quantitation of 0.1 μg/l for glyphosate and 0.5 μg/l for AMPA are sufficient to determine occupational exposure as well as some of the background exposure in the general population.