Abstract:

A method for the determination of fatty acid esters of chloropropanediols in milk samples by gas chromatographymass
spectrometry (GC-MS) was established. The milk samples were ultrasonically extracted with hexane, followed by
transesterification with sodium methylate/methanol, and purified by matrix solid-supported liquid-liquid extraction (SLE).
After being derivatized with heptafluoro butyrylimidazole (HFBI), fatty acid esters of 3-monochloropropane-1,2-diol
(3-MCPD esters) and 2-monochloropropane-1,3-diol (2-MCPD esters) were determined using GC-MS. The target
compounds were separated on a HP-5 capillary chromatographic column, and the tandem mass spectrograph was operated
in the selected ion-monitoring mode (SIM). An excellent linear correlation in the range of 5–500 μg/L was acquired for both
3-MCPD esters and 2-MCPD esters with coefficient correlations higher than 0.999 5. The limits of detection (LODs) for
both 3-MCPD esters and 2-MCPD esters were 2.0 μg/kg. The recoveries of the 3-MCPD esters and 2-MCPD esters spiked in the blank
milk at levels of 10, 50, 100 and 200 μg/kg were all in the range of 73.5%–106.6%, with relative standard deviations (RSDs) less than
10%. The method was found to be suitable for the determination of 3-MCPD esters and 2-MCPD esters in milk samples. A total of
30 milk samples were analyzed using this method, and the concentrations of 3-MCPD esters and 2-MCPD esters were determined to
be relatively low, ranging from undetectable levels to 13.8 μg/kg. According to the estimated exposure assessment results, there was
relatively low health risk associated with the intake of 3-MCPD esters and 2-MCPD esters from the milk for the general Chines epopulation.

Key words: fatty acid esters of chloropropanediols, stable isotopic dilution, gas chromatography-mass spectrometry (GC-MS), milk