Validation of a simple method for the determination of glyphosate and aminomethylphosphonic acid in human urine by UPLC-MS/MS

Environmental pollutants such as pesticides can be detrimental to human health and/or to the environment. Their excessive use may produce toxicity through various mechanisms. Glyphosate is a broad-spectrum herbicide with a high worldwide distribution. Due to this, this chemical is classified as a 'Group 2A - probably carcinogenic to humans' by the International Agency for Research on Cancer. Human biomonitoring is considered the golden standard for exposure assessment and provides a very useful tool in public health. Therefore, it is important to develop methods to determine traces of this herbicide and its metabolite, aminomethyl phosphonic acid, in human biological samples. A new method for glyphosate and aminomethyl phosphonic acid determination in human urine is herein described and discussed. It is based on the derivatization procedure with Fluorenylmethoxycarbonyl chloride and quantification by ultra-performance liquid chromatography-tandem mass spectrometry. The method was optimized and suitably validated, with a linear range from 1 to 20 mu g L-1 in the case of glyphosate and 0.5-20 mu g L-1 for aminomethyl phosphonic acid. Limits of detection and quantification were 0.5 and 1 mu g L-1 for glyphosate and 0.1 and 0.5 mu g L-1 for aminomethyl phosphonic acid, respectively. Mean relative recoveries ranged 108-109% for glyphosate and 104-119% for aminomethyl phosphonic acid and intermediate precision values varied from 11.90 to 12.70% for glyphosate and 4.8-9% for aminomethyl phosphonic acid. The validated method has been applied in human urine from female farmers indirectly exposed to pesticides. This procedure can be used to monitor potential exposure of humans to glyphosate and aminomethyl phosphonic acid in epidemiological studies and for routine controls in public health.