Sample preparation for MOSH/MOAH analysis: applicability of current methods and analytical limits

Mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) are petroleum-derived food contaminants consisting of highly complex unresolved mixtures with variable chemical composition. Their determination generally relies on multi-step analytical workflows involving extraction or, in some cases, simultaneous saponification/extraction, followed by one or several purification steps prior to on-line liquid chromatography–gas chromatography with flame ionization detection (LC-GC-FID). Complementary techniques such as comprehensive two-dimensional gas chromatography (GC×GC) may additionally be used for confirmation and improved characterization.
Despite major analytical progress, particularly in terms of method harmonization and standardization, MOSH/MOAH analysis remains associated with significant analytical challenges. High measurement uncertainty can notably be observed for complex and interference-rich matrices. Sample preparation is a critical step, as incomplete removal of interfering compounds may compromise chromatographic interpretation and lead to overestimation or underestimation of MOSH and MOAH fractions. In addition, each sample preparation step contributes to the overall analytical variability, while matrix effects may strongly affect method performance depending on the nature of the sample.
This presentation will provide an overview of current sample preparation strategies applied in MOSH/MOAH analysis. Based on our experience with the analysis of a wide range of matrices, the discussion will focus on the applicability and limitations of these methods for challenging samples such as food additives, oleoresins, novel foods, or processed fats and oils. Current bottlenecks and remaining challenges associated with reliable quantification at concentration levels expected in future regulations will also be discussed.