Trust Your Results in Mineral Oil Analysis

Significance of the Topic

The presence of mineral oil hydrocarbons in food, packaging and cosmetics has raised major safety concerns worldwide. Recent contamination events such as the detection of MOH in infant formula have highlighted the need for reliable methods that deliver both qualitative and quantitative confidence. The two main classes MOSH and MOAH require robust workflows due to unresolved chromatographic humps and overlapping peaks which hinder accurate integration.

Objectives and Study Overview

This application note presents a novel workflow combining liquid chromatography fractionation with comprehensive two dimensional gas chromatography coupled to time of flight mass spectrometry and flame ionization detection. The goal is to reduce uncertainty in MOSH/MOAH analysis by improving peak integration and confirmation via mass spectral data. Both synthetic reference mixtures and real world animal feed samples were evaluated to assess performance.

Methodology

The method relies on:

• LC fractionation using silica column and wavelength detection to separate MOSH and MOAH fractions
• Transfer of defined retention time windows for MOSH and MOAH into the GCxGC system
• Parallel GCxGC-TOFMS and GCxGC-FID acquisition to obtain qualitative MS confirmation and quantitative FID response
• Data processing in ChromaTOF software with a dedicated trimming algorithm to remove riding peaks from unresolved humps and interpolate baseline signals

Instrumentation Used

• Agilent 1260 Infinity II HPLC with Allure Silica column and variable wavelength detector
• Axel Semrau CHRONECT LC-GC interface for automated fraction transfer
• LECO GCxGC QuadJet thermal modulator with Rxi-17SilMS and Rxi-1ms columns
• LECO Pegasus BT 4D time of flight mass spectrometer and flame ionization detector with dedicated gas flows and temperature programs
• ChromaTOF software updated for MOSH/MOAH peak trimming and spectral filtering

Main Results and Discussion

The system was validated using a paraffin oil and C8–C40 alkane mix, showing response factors within ±20% for C10–C50. Application to animal feed matrices demonstrated agreement between traditional LC-GC-FID and the new LC-GCxGC-TOFMS/FID workflow for total MOSH and MOAH quantitation. The new algorithm efficiently removed narrow peaks riding on chromatographic humps while preserving the unresolved envelope. Mass spectral filters enabled rapid confirmation of aromatic structures and improved classification of MOAH subclasses.

Benefits and Practical Applications

• Enhanced reliability by combining selective MS confirmation with sensitive FID quantitation
• Reduction of integration uncertainty through automated hump trimming
• Simultaneous targeted and non targeted screening capacity via full scan TOFMS data
• Compliance with evolving regulatory guidelines for MOH monitoring in food and consumer goods

Future Trends and Applications

Further developments may include integration with high resolution mass analyzers for even deeper non targeted screening, expansion to a broader range of food contact materials and cosmetic products, and continuous improvement of software algorithms for peak detection in complex matrices. Growing interest in non UV active MOH and hydrocarbon migrants will drive new method extensions.

Conclusion

This work demonstrates a state of the art LC-GCxGC-TOFMS/FID platform that harmonizes official LC-GC-FID protocols with advanced hyphenated detection and novel data processing. The result is a robust and confident workflow for accurate MOSH and MOAH analysis across diverse sample types, addressing key challenges in chromatographic integration and compound confirmation.

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