Insight into what IP346 measures through characterization of MOAH distribution in DMSO and organic phase by comprehensive two-dimensional gas chromatography.

Mineral oil hydrocarbons are complex mixture used in a wide range of applications, including lubricants, printing inks, and medicinal formulations, and are often found in food due to contamination from different processing and environmental sources. To be placed on the market, these oils must comply with the IP346 regulatory standard method. The IP346 method has been correlated with mouse skin painting assays for evaluating the carcinogenic and genotoxic potential of mineral oils, based on its DMSO-extractable fraction. Therefore, compliance with the IP346 method ensures consumer safety. However, to the best of the authors' knowledge, the DMSO-extractable fraction has not been characterized from a food contaminant perspective using state-of-the-art analytical techniques, such as comprehensive multidimensional gas chromatography. In this study, the IP346 method was miniaturized and adapted to enable GC × GC characterization of DMSO extracts while reducing solvent and sample consumption. A broad range of mineral oil samples was selected to cover a wide distribution of aromaticity and alkylation degree. The results show that GC × GC enables detailed characterization of the DMSO extract, revealing an enrichment in ≥ 3 ring aromatic compounds that are non-alkylated or weakly alkylated, regardless of the initial aromatic and alkylation distribution of the oil. Although the DMSO extract is enriched in ≥ 3 rings MOAH, higher alkylated species are not extracted by DMSO and remain in the organic phase, no matter their aromatic ring number. UV measurements of the DMSO extracts further demonstrate a strong correlation between the concentration of ≥ 3-ring MOAH and the UV response.