Comparative analysis of detection techniques for glyphosate in urine and in water

Abstract

Abstract Background Glyphosate is the declared active component of the most extensively used herbicides in the world, and is therefore widely present in the environment. Glyphosate urinary levels represent a relevant biomarker for each individual’s exposure to glyphosate-based herbicides. However, GLY urine level measurement is controversial because different detection methods have led to contradictory results, especially in the cases of enzyme-linked immunosorbent assay (ELISA) versus liquid chromatography coupled to tandem mass spectrometry (LC/MS–MS) for urine, and ELISA versus high-performance liquid chromatography coupled to fluorescence detection (HPLC/Fluo) for water. Methods We compared the ELISA method to the LC/MS–MS or HPLC/Fluo one by submitting to two laboratories (Biocheck, Germany and Labocéa, France, respectively) identical urine and water samples, spiked or not with precise concentrations of glyphosate, but also with two chemically similar molecules: glycine and aminomethylphosphonic acid, GLY’s analogue and primary metabolite, respectively. Results Both laboratories claimed similar glyphosate quantification threshold (LOQ): 0.08 and 0.05 ng/mL, respectively. Each one of the tested methods proved to be specific for glyphosate and therefore did not result in any cross-detection with glycine and aminomethylphosphonic acid. However, these methods showed differences both in reproducibility and reliability depending on the matrix used (water or urine). Conclusion While the ELISA method gave less accurate results than the HPLC/Fluo technique when applied to water samples, the glyphosate concentrations measured in urine were much more reliable and reproducible with the ELISA technology than those obtained with the LC/MS–MS one.