Quantitative determination of sodium monofluoroacetate "1080" in infant formulas and dairy products by isotope dilution LC-MS/MS.

A fast and easy-to-use confirmatory liquid-chromatography tandem mass-spectrometry (LC-MS/MS) based-method was developed for the analysis of the pesticide sodium monofluoroacetate (MFA, also called "1080") in infant formulas and related dairy products. Extraction of the compound encompassed sample reconstitution and liquid-liquid extraction under acidic conditions. Time-consuming solid-phase extraction steps for clean-up and enrichment and tedious derivatisation were thus avoided. Resulting sample extracts were analysed by electrospray ionisation (ESI) in negative mode. Quantification was performed by the isotopic dilution approach using (13)C-labelled MFA as internal standard. The procedure was validated according to the European document SANCO/12571/2013 and performance parameters such as linearity (r(2) > 0.99), precision (RSD(r) ≤ 9%, RSD(iR) ≤ 11%) and recovery (96-117%) fulfilled its requirements. Limit of quantifications (LOQ) was 1 µg kg(-1) for infant formulas and related dairy products except for whey proteins powders with a LOQ of 5 µg kg(-1). Method ruggedness was further assessed in another laboratory devoted to routine testing for quality control.