Journal of Chromatography Open (Nov 2022)
Quantification of mineral oil aromatic hydrocarbons by number of aromatic rings via comprehensive two-dimensional gas chromatography: First results in food
Abstract
ABSTRACT: The established analysis of mineral oil aromatic hydrocarbons (MOAH) provides results on the sum of all hydrocarbons with an aromatic moiety present in mineral oil contaminations. As MOAH substances are not believed to have equal toxicity, the European Food Safety Authority (EFSA) stated a need for a quantitative method for the determination of MOAH grouped according to the number of aromatic rings. The separation power of comprehensive two-dimensional gas chromatography (GC×GC) and the chromatographic grouping according to aromatic moieties renders quantification by means of flame ionization detection (FID) possible. A data processing method was established, which allows the subtraction of single peaks originating from the food and not considered to be MOAH. The quantification method was validated by spiking experiments and first results on 10 rice and 34 infant formula samples are given. The content of ≥3 ring MOAH in rice were in the range of 0.09–1.3 mg/kg, the contents for infant formula were below LOQ (between <0.05 and <0.1 mg/kg), except for one sample. Data from GC×GC-mass spectroscopy (MS) with exact mass accuracy of a test mixture containing mineral oil hydrocarbons (MOH) up to the volatility of n-pentacontane (n-C50) were used to establish the cuts between the individual MOAH. Furthermore, the liquid chromatography (LC) and GC×GC retention times of MOAH were determined according to the C-fractions as requested by the EFSA and elucidated in terms of number of aromatic rings and degree of alkylation. For MOAH analysis epoxidation is a required procedure for certain food matrices to eliminate interfering olefins and leads to losses of the analyte. These were quantified in dependance to different aromatic moieties. The elution of 6 and 7 ring MOAH compared to the standard LC fraction window was explored and, finally, more selective LC pre-separation tested in terms of chromatographic removal of olefins from the ≥3 ring MOAH.
