Analytical method for the trace determination of esterified 3- and 2-monochloropropanediol and glycidyl fatty acid esters in various food matrices.

Fatty acid esters of 3-monochloro-1,2-propanediol (3-MCPDEs), of 2-monochloro-1,3-propanediol (2-MCPDEs) and of 2,3-epoxy-1-propanol or glycidol (GEs), which are considered to be deleterious to human health, may occur in a broad variety of food samples. A proper risk assessment of those substances requires the availability of robust occurrence data; in this respect concerns have been raised regarding the reliability of results obtained with the currently available methods to determine those substances in processed food. This article presents an indirect analytical procedure for the simultaneous determination of 3-MCPDEs, 2-MCPDEs and GEs in a wide variety of food products after extraction by pressurised liquid extraction (PLE) and determination by gas chromatography mass-spectrometry (GC-MS). For the differentiation of MCPDEs and GEs, the latter were first converted to monobromopropanediol esters (MBPDEs) in acid aqueous solution of sodium bromide. MCPDEs and MBPDEs were then hydrolysed under acidic conditions followed by derivatisation of the released free (non-esterified) form in ethyl acetate with phenyl boronic acid (PBA). Quantification of the analytes was carried out using the isotopic labelled analogues of both MCPDEs and GEs. Limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 7-17mgkg(-1) and 13-31mgkg(-1) respectively, while the working range of the method was between LOQ and 1850mgkg(-1) expressed on fat basis. The developed method was successfully applied for the analysis of the target compounds in more than 650 different food samples covering the following commodities: bread and rolls, fine bakery wares, smoked fish products, fried and roasted meat, potato based snacks and fried potato products, cereal-based snacks and margarines.