UTILISATION OF REVERSE COLUMN SET FOR MINERAL OIL QUANTIFICATION IN FOOD.

Mineral oil hydrocarbons (MOH) is a ubiquitous food contaminant divided into aromatic (MOAH) and saturated hydrocarbons (MOSH). MOAH are potentially carcinogenic, while MOSH may accumulate in the human body. The toxicity and the occurrence of these compounds must be fully clarified before any legislation may take place. Such investigation is currently ongoing, but the main limitation remains the analytical method to provide additional information on the sub-class distribution of both MOSH and MOAH and limit the number of false positives.
In this regard, the use of comprehensive gas chromatography (GC×GC) has several well-known advantages for a complete characterization of MOH. The hyphenation with the liquid chromatographic (LC) purification provides a fully automated system (i.e. LC- GC×GC-ToFMS/FID), enhancing sensitivity and reducing extra manipulation contamination. Coupled with ToFMS and FID, this technique allows separating and, thanks to a recently developed software, quantifying the different subclasses of MOSH and MOAH1. The coupling with a sensitive ToFMS detector allows a complete characterization of the contamination, detecting the presence of markers to correlate with contamination sources, and providing additional information on other contaminants (e.g., PCB) and interferences present. Moreover, the use of a reverse column set allows the separation of some epoxidation-resistant interferences in the MOAH fractions, avoiding overestimation of the fraction and a more robust quantification. However, using a reverse column set, attention needs to be paid to adapt the integration windows to consider the different elution of the more polar MOAH compared to the traditional non-polar column used in LC-GC-FID.
1. Bauwens, G., Pantó, S. & Purcaro, G. Mineral oil saturated and aromatic hydrocarbons quantification: Mono- and two-dimensional approaches. J. Chromatogr. A 1643, (2021) 462044.