Mineral oil residues in food – automated removal of natural interferences by online epoxidation

Mineral oil (MO) residues in food raised public concern due to some elevated concentrations up to several thousand milligrams per kilogram food. Due to the chemical structures two groups of MOs can be differentiated.

Mineral oil saturated hydrocarbons (MOSH) consist of linear and branched alkanes, and alkyl-substituted cyclo-alkanes, whilst mineral oil aromatic hydrocarbons (MOAH) include mainly alkyl-substituted polyaromatic hydrocarbons. Technical grades of mineral oils contain aromatic hydrocarbons in a concentration range from 15-35%. The determination of MOSH and MOAH in food can be done by an automated LC-GC-FID system for routine analysis. Unfortunately some food material contain natural occurring olefins (eg. Squalene, sterenes, carotenoids…), which can interfere with the analysis of the aromatic fraction. These interferences can be removed by epoxidation with 3-chloroperbenzoic acid (mCPBA).