Determination of short- and medium-chained chlorinated paraffins in salmon samples using GC Orbitrap-MS

Importance of the Topic

Chlorinated paraffins (CPs) are persistent organic pollutants widely used as flame retardants and plasticizers. Short-chain (SCCPs) and medium-chain (MCCPs) variants pose analytical challenges due to complex congener mixtures and co-elution with other halogenated contaminants. High-resolution Orbitrap mass spectrometry coupled with gas chromatography offers enhanced selectivity and sensitivity, addressing growing regulatory demands under the Stockholm Convention.

Study Objectives and Overview

This work evaluated the quantitative performance of a Q Exactive GC Orbitrap system for SCCP and MCCP determination in salmon. Key goals included assessing linearity, sensitivity, and selectivity in the presence of co-eluting polychlorinated biphenyls (PCBs), and comparing sample clean-up strategies.

Methodology and Instrumentation

Samples were extracted by accelerated solvent extraction using acetone/hexane. Cleanup employed sulfuric acid-treated silica and optional Florisil columns to separate CPs and PCBs. Calibration curves covered 0.1–15 ppm with isotopically labeled hexachlorodecane and hexachlorocyclohexane as internal standards.

• Gas chromatography: TRACE 1310 with TG5-SilMS column
• Ionization: negative chemical ionization with methane
• Mass spectrometry: full-scan Orbitrap at 60 000 and 120 000 resolution, m/z 50–650

Key Results and Discussion

Linearity exceeded R2 > 0.99 for both SCCP and MCCP congeners. Limit of quantification reached 0.1 ppb for SCCPs and 1.5 ppb for MCCPs. High resolution allowed accurate quantification even with significant PCB co-elution, with relative deviations below 10% for most homologues. Salmon samples cleaned with Florisil showed clean chromatograms, while uncleaned extracts revealed multiple overlapping POPs. Orbitrap analysis delivered reliable results in both cases, whereas low-resolution methods failed in complex matrices.

Benefits and Practical Applications

• Simultaneous quantification of SCCPs, MCCPs, and PCBs in one run
• Reduced sample preparation without compromising accuracy
• Enhanced selectivity minimizes interferences in complex food matrices
• Improved sensitivity supports trace-level monitoring in regulatory compliance

Future Trends and Opportunities

As the list of regulated persistent organic pollutants expands, high-resolution GC-Orbitrap will enable broad-scope screening and faster workflows. Integration with advanced data processing and green extraction techniques could further streamline multi-residue analysis in food and environmental laboratories.

Conclusion

The Q Exactive GC Orbitrap system demonstrates excellent linearity, sensitivity, and selectivity for SCCP and MCCP determination in salmon. Its ability to resolve co-eluting POPs simplifies sample preparation and improves quantitative reliability, offering a powerful tool for modern monitoring of chlorinated paraffins and related contaminants.

Reference

• Tomy, G.T. The Handbook of Environmental Chemistry, Vol 10, 2010.
• Stockholm Convention on Persistent Organic Pollutants, UNEP-POPS-COP.8/14, 2017.
• Gluege, J.; Wang, Z. Science of the Total Environment, 573, 1132–1146, 2016.
• Reth, M. et al. Analytical and Bioanalytical Chemistry, 378, 1741–1747, 2004.