Selective method for quantitative determination of glyphosate, aminomethylphosphonic acid, and glufosinate in animal products using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)

Abstract

Glyphosate and glufosinate are broad-range, non-selective herbicides that contaminate plant products used in fattening farm animals which in turn bears the risks of contamination of the whole food chain. The goal of this study is to develop a selective procedure for the chromato-mass spectrometric determination of glyphosate, aminomethylphosphonic acid (glyphosate metabolite) and glufosinate in meat, offal and milk. The limit of quantitative determination of glyphosate and glufosinate in meat and offal is 0.05 mg/kg, aminomethylphosphonic acid is 0.4 mg/kg; the limit of quantitative determination of glyphosate and glufosinate in milk is 0.02 mg/kg, aminomethylphosphonic acid is 0.05 mg/kg. The compounds to be determined are extracted from the objects under study with a solution of sulfbsalicylic acid, the primary purification of the extracts is carried out using a reverse-phase C18 sorbent, the compounds to be determined are derivatized using 9-fluorenylmethoxycarbonyl chloride, and the final purification of the derivatives is carried out on a sorbent exhibiting weak cation exchange properties. The purified extract is concentrated, diluted with a mixture of methanol and acetic acid in water, centrifuged and then used for analysis. Chromatographic separation is performed on a column with a reversed-phase C18 sorbent. Tandem mass-spectrometry is used for detection of the compounds under study. The calibration dependences for the determined compounds are linear, the correlation coefficient (K) > 0.99. The validation of the procedure showed that the relative expanded uncertainty in the lower range of the determined contents ranged from 27 to 41% for glyphosate, from 25 to 29% for aminomethylphosphonic acid, and from 25 to 34% for glufbsinate, depending on the type of object of analysis. The obtained values of the limit of quantitative determination are consistent with the temporary maximum allowable levels set in SanPiN 1.2.3685-21.