DETERMINATION OF MOSH AND MOAH BY GC×GC-TOFMS

Significance of the Topic

The presence of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in food due to migration from packaging materials poses an increasing public health concern across the European Union. These contaminants derive primarily from inks and recycled paperboard, with alkane chains ranging from C13 to C45. Reliable, sensitive analytical methods are essential for regulatory compliance, consumer safety and accurate source identification.

Aims and Study Overview

This study evaluates a one-run, comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) approach for simultaneous MOSH/MOAH determination. The goal was to develop a robust method that improves resolution and identification of individual hydrocarbon families compared to conventional one-dimensional and heart-cut LC-GC-FID techniques.

Methodology and Used Instrumentation

Sample fractions enriched in MOSH and MOAH were obtained via a commercial LC-GC interface, evaporated to approximately 350 µL per fraction, and injected onto the GC×GC system. The analytical platform comprised LECO’s Pegasus BT 4D GC×GC-TOFMS with the following key components and conditions:

• Columns: First dimension Rxi-17SILMS (12 m × 0.25 mm × 0.25 µm); second dimension Rxi-1HT (1.05 m × 0.25 mm × 0.10 µm)
• Dual-stage quad-jet thermal modulator with primary oven program from 40 °C to 360 °C (5 °C/min) and secondary oven offset +7 °C
• Modulator hot pulse settings: 1.65 s during initial run, then 1.80 s
• Inlet conditions: splitless 1 mL/min flow at 330 °C
• Transfer line temperature: 340 °C; ion source at 280 °C; electron ionization energy 70 eV
• Acquisition: 200 spectra/s; mass range 40–700 m/z

Main Results and Discussion

The combination of two orthogonal column chemistries achieved clear separation of linear, branched and cyclic alkanes (MOSH) from alkylated aromatics (MOAH). High-speed TOFMS acquisition captured full-range mass spectra for each modulation slice, enabling precise compound family classification with ChromaTOF software. Surface plots and contour chromatograms demonstrated well-defined elution regions for each hydrocarbon group. This one-run approach provided improved peak capacity and deconvolution capacity compared to traditional 1D GC methods.

Benefits and Practical Applications of the Method

• Enhanced resolution and sensitivity for trace-level MOSH/MOAH detection
• Rapid confirmation and differentiation of mineral oil contaminants versus biogenic terpenoids or synthetic polymer leachables
• Single-injection workflow reduces analysis time and risk of cross-contamination
• High-quality mass spectral data support reliable quantitation and identification

Future Trends and Applications

Ongoing developments may include integration of high-resolution accurate mass detectors, automated sample preparation protocols, and advanced chemometric tools for data interpretation. Standardized GC×GC-TOFMS workflows combined with regulatory harmonization could further enhance routine monitoring of packaging-related contaminants. Machine learning approaches may also streamline peak classification and anomaly detection in complex food matrices.

Conclusion

The GC×GC-TOFMS method presented demonstrates significant advantages in the determination of MOSH and MOAH, delivering superior separation, robust identification and efficient workflows. Its application supports improved food safety assessment and helps trace contamination sources in packaging.