Direct determination of glyphosate and its metabolite in the plant raw material and environmental objects by chromatography-mass spectrometry

Abstract

Glyphosate is a popular herbicide often used for desiccation of crops. The use of glyphosate-based chemicals leads to the contamination of agricultural products, soils, surface and groundwater. For safety control of raw materials of the plant origin and environmental objects, a technique based on the tandem chromato-mass-spectrometry was developed to provide for the quantitative determination of glyphosate and aminomethylphosphonic acid (AMPA) without prior derivatization. The technique is characterized by a relatively simple and cost-effective sample preparation procedure. The compounds are extracted from plant raw materials with an acetic acid solution of methanol in water, in the presence of 2-aqueous disodium salt of ethylenediamine-N,N,N’,N’-tetraacetic acid (EDTA-Na2) and dichloromethane. Extraction of analytes from water samples is carried out in the presence of EDTA-Na2 and acetic acid; whereas their extraction from soil samples is carried out with a weak solution of ammonia. The extracts are purified by solid phase extraction (SPE), and proteins are precipitated with acetonitrile. Linear-dynamic ranges of glyphosate and AMPA determination are characterized by calibration curves with correlation coefficients (R) ≥0.99. The working range of glyphosate and AMPA determination in raw materials of plant origin was from 0.1 to 5.0 mg/kg; in surface and ground water from 0.001 to 0.05 mg/liter (glyphosate) and from 0.002 to 0.05 mg/liter (AMPA); in soils from 0.02 to 0.8 mg/kg (glyphosate) and from 0.04 to 0.8 mg/kg (AMPA). The values of the relative standard deviation range from 1.8 to 19.5%, with recovery levels ranging from 80.5 to 108.1%. The achieved values of the determination limits are consistent with the maximum permissible levels indicated in TR CU 015/2011 and SanPiN 1.2.3685–21.