A novel workflow for the simultaneous determination of MOSH/MOAH and PAHs in fat oil-derived food additives by off-line HPLC–GC×GC–FID/TOFMS

Contamination of foodstuffs by mineral oil hydrocarbons (MOH) and polycyclic aromatic hydrocarbons (PAHs) is of concern for human health. MOH are structurally classified into MO saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH). The latter may contain compounds with carcinogenic and genotoxic properties, whereas MOSH tends to bioaccumulate in tissue and organs. PAHs, which originate from incomplete combustion processes, are also carcinogenic.
Structurally-speaking, MOAH and PAHs share a polyaromatic structure; however, MOAH are alkylated compounds, while PAHs are not. The analysis of these two classes of compounds is traditionally performed using separate methodologies due to different analytical requirements. In fact, MOAH require FID for accurate quantification, while PAHs need a more sensitive and selective detector, such as a MS. Both groups of contaminants can however share a similar sample preparation procedure.
The aim of this study was hence to develop a comprehensive analytical workflow allowing the simultaneous determination of MOSH, MOAH, and PAHs in complex matrices such as fat and oil derived food additives, for which no validated analytical method is currently available.
The proposed workflow is based on a modified version of ISO 20122:2024, originally developed for the determination of MOSH&MOAH in vegetable oils, and adapted to address the complexity of food additives such as E471, E322, E472, E473, E475. The method includes a microwave-assisted saponification/extraction step, followed by HPLC fractionation, allowing the separation of the MOSH fraction from the combined MOAH and PAHs fraction. Subsequent analysis is performed using comprehensive two-dimensional gas chromatography coupled with FID and time-of-flight MS (GC×GC–FID/TOFMS).
A major analytical challenge associated with these matrices is the presence of interfering compounds, which often hinder accurate contaminant quantification. In this study, purification of the MOAH was achieved through epoxidation, while PAHs analysis does not require chemical purification due to the high selectivity of the combined GC×GC-TOFMS.