A Robust Transferable Method for the Determination of Glyphosate Residue in Liver After Derivatization by Ultra-high Pressure Liquid Chromatography–Tandem Mass Spectrometry

Abstract

Glyphosate determination in liver is challenging due to this particular molecule/matrix combination. Glyphosate is a very polar molecule and liver composition is highly variable between individuals and species. Since 2014, the Multiannual Control Program (MACP) of the European Union (EU) demands to analyse glyphosate in food of animal origin on a voluntary basis. Moreover, this analysis will be mandatory in 2017. This paper describes a robust and easily transferable method for glyphosate quantification in liver of animal origin by means of liquid chromatography–tandem mass spectrometry (LC-MS/MS). An intensive clean-up was used to eliminate matrix interferences and was combined with a derivatization step which ensures good retention of glyphosate on a conventional reverse-phase LC column. This method allows to meet the MACP requirements without a time-consuming change in the set-up of the routinely used LC-MS/MS system. Furthermore, it allows the use of an LC column and mobile phases often used in multi-residue analysis. The analytical method was validated according to the SANCO/12571/2013 criteria. Isotopic dilution was used to quantify glyphosate, leading to mean apparent recoveries of 115 and 101 % for the low (0.025 mg kg−1) and the high (0.250 mg kg−1) fortification levels, respectively. At both levels, the relative standard deviation was below 10 %. The limit of quantification of 0.025 mg kg−1 was found to be satisfactory as it was below the maximum residue level (MRL) value set at 0.050 mg kg−1 for glyphosate in liver. It is also the lowest MRL for all commodity types.