Mineral Oil Residues in Food Part 1- Dry Food (Flour, Noodles and Rice)

Significance of the topic

Mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) are environmental contaminants that can accumulate in grain-based foods such as flour, noodles and rice due to their high global consumption. Routine monitoring of these residues is essential for food safety assessment and regulatory compliance.

Study objectives and overview

This work presents a fully automated online LC-GC-FID method for the simultaneous quantification of MOSH and MOAH fractions in dry, non-fatty food matrices. The study aims to streamline sample preparation, separation and detection to support high-throughput routine analysis.

Methodology and Instrumentation

Samples (1–10 g) are extracted with hexane/ethanol (1:1) in the presence of internal standards. The organic extract is washed, dried, concentrated to 1 mL and analyzed by injecting 50 µL into an LC-GC-FID system. The LC system Shimadzu LC-20AD with an Allure Silica column employs an n-hexane/dichloromethane gradient for fractionation. The MOSH and MOAH fractions are transferred via a Chronect interface to a dual-channel GC-2010 Plus FID system equipped with Restek MXT Siltek and MTX-1 columns. Quantification uses bicyclohexyl for MOSH and 2-methylnaphthalene for MOAH with integration of hydrocarbon humps in defined carbon number ranges (C10–C25).

Main Results and Discussion

Typical chromatograms demonstrated clear separation of MOSH and MOAH fractions. A spaghetti sample showed 12.7 mg/kg MOSH in the C16–C35 region, while a rice sample revealed additional odd-numbered n-alkanes (C21–C35). The method provided reproducible retention times and stable response across the target ranges.

Benefits and Practical Applications

The automated LC-GC-FID workflow reduces manual handling and increases throughput, making it suitable for routine quality control and compliance testing in the food industry. It offers reliable discrimination between MOSH and MOAH with minimal operator intervention.

Future Trends and Opportunities

Future developments may include adaptation to fatty and complex matrices, integration of mass spectrometric detection for enhanced specificity, lower detection limits to meet evolving regulatory requirements and implementation of standard limits for MOSH/MOAH in food products.

Conclusion

The presented online LC-GC-FID method delivers a fast, robust and fully automated solution for simultaneous determination of MOSH and MOAH in dry food matrices, supporting routine analytical demands.

Reference

• EFSA Panel on Contaminants in the Food Chain (CONTAM) Scientific Opinion on Mineral Oil Hydrocarbons in Food DOI:10.2903/j.efsa.2012.2704
• Statista Global per capita rice consumption since 2000
• International Pasta Organisation Global pasta consumption data
• Bundesinstitut für Risikobewertung (BfR) Method for determination of hydrocarbons from mineral oil or plastics