Non-Intentionally Added Substances in Food and Food Contact Material – Determination of Mineral Oil Hydrocarbons with LC-GC Online Technique

Importance of the Topic

Non-intentionally added substances (NIAS), in particular mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH), can migrate from food contact materials or arise from contaminants and pose potential health risks. Sensitive and reliable analytical methods are essential to monitor their levels in various foods and packaging to protect consumers and support regulatory oversight.

Objectives and Study Overview

The study aimed to implement and validate an on-line HPLC-GC-FID technique following EN 16995:2017 for the determination of MOSH and MOAH residues in food and food packaging. Emphasis was placed on achieving high sensitivity, reproducibility, and throughput while simplifying sample handling.

Methodology

Sample Preparation and Extraction:

1. Weigh 1–10 g of homogenized, finely ground sample.
2. Add hexane/ethanol (1:1) with an internal standard mixture (Restek MOSH/MOAH, Cat.# 31070).
3. Extract at room temperature for 2 hours with occasional shaking.
4. Add water, centrifuge, discard aqueous phase; repeat washing.
5. Dry organic layer over anhydrous sodium sulfate and concentrate to 1 mL.
6. Transfer to a 2 mL autosampler vial.

Chromatographic Procedure:

1. Inject 50 µL onto the HPLC column.
2. Separate MOSH and MOAH fractions via normal-phase HPLC.
3. Transfer 450 µL of each fraction on-line to the GC pre-columns.
4. Perform rapid temperature-programmed GC analysis with flame ionization detection (FID).

Instrumentation Used

The system comprised a Shimadzu Nexera HPLC with dual LC-20ADXR pumps, CBM-20A controller, SPD-20A UV detector, coupled to a GC-2010 Plus equipped with two FID detectors and a PAL autosampler. All operations were managed by CHRONOS and LabSolutions software. Optional features include fraction collection for GC-MS/GCxGC-MS analysis and on-line epoxidation to remove co-extractives.

Key Results and Discussion

Analysis of a recycled paper grade sample yielded MOSH (C16–C35) at 787 ± 99 mg/kg and MOAH (C16–C35) at 110 ± 12 mg/kg. The method demonstrated high reproducibility, sensitivity down to sub-mg/kg levels, and consistent FID response across hydrocarbon structures. On-line coupling eliminated the need for manual SPE, reducing solvent usage and potential contamination.

Benefits and Practical Applications

• Routine-capable workflow with automated sample preparation and analysis.
• Improved throughput and reduced labor compared to off-line methods.
• High accuracy and reproducibility suitable for QA/QC labs.
• Modularity to integrate advanced detection (GC-MS, GCxGC-MS, GC-TQMS).

Future Trends and Applications

Advancements may include expanded use of on-line fractionation coupled to high-resolution mass spectrometry for structural elucidation, further automation of sample derivatization (e.g., epoxidation), and adaptation of the platform to other classes of NIAS. Integration with digital data management will enhance real-time monitoring and regulatory compliance.

Conclusion

The on-line HPLC-GC-FID approach delivers a fast, robust, and reliable solution for determining MOSH and MOAH in food and contact materials. By streamlining sample preparation and leveraging automated fraction transfer, the method addresses key analytical challenges and supports routine monitoring and risk assessment.

References

1. EFSA. Mineral Oil Hydrocarbons in Food. EFSA Journal. 2012;10(6):2704.
2. European Commission Recommendation (EU) 2017/84 of 16 January 2017.
3. EN 16995:2017. Foodstuffs – Determination of MOSH and MOAH by on-line HPLC-GC-FID.
4. Nestola M, Schmidt TC. Journal of Chromatography A. 2017;1505:69–76.