Determination of Short and Medium Chained Chlorinated Paraffins in Salmon Samples using GC Orbitrap-MS

Significance of the Topic

Salmon is a key food matrix for monitoring chlorinated pollutants such as SCCPs and MCCPs. High complexity of these compounds and co-eluting PCBs presents analytical challenges. High-resolution GC-MS with Orbitrap technology addresses sensitivity, selectivity and dynamic range issues.

Objectives and Study Overview

The study assesses the performance of the Thermo Scientific Q Exactive GC Orbitrap GC-MS/MS system in full-scan negative chemical ionisation at 60k and 120k resolution. It evaluates linearity, detection limits and selectivity for SCCPs (C10-C13) and MCCPs (C14-C17) in standards and salmon samples with and without clean-up.

Methodology

• Sample preparation by accelerated solvent extraction and optional Florisil clean-up.
• Calibration using technical mixtures of SCCP and MCCP at 0.1–15 ppm with 13C-hexachlorodecane and ε-HCH as internal standards.
• GC conditions: Thermo Scientific TRACE 1310, TraceGOLD TG5-SilMS 15 m×0.25 mm×0.25 μm, splitless injection 1.5 µL.
• MS conditions: Q Exactive GC Orbitrap GC-MS/MS, NCI with methane, full-scan m/z 50–650, resolution 60 000 and 120 000 FWHM at m/z 200.

Used Instrumentation

• Thermo Scientific Q Exactive GC Orbitrap GC-MS/MS system
• Thermo Scientific TRACE 1310 gas chromatograph
• Thermo Scientific TraceGOLD TG5-SilMS GC column

Main Results and Discussion

Linearity was excellent with R² > 0.99 for individual CP congeners across 1–5000 pg/µL. LOQ values of 0.1 ppb (SCCP) and 1.5 ppb (MCCP) and LODs down to 0.05 ppb and 0.3 ppb were achieved. High resolution allowed accurate quantification in presence of co-eluting PCBs without peak distortion. Salmon extracts prepared with or without Florisil clean-up showed < 10 % deviation in total CP levels using Orbitrap MS, whereas low-resolution methods overestimated CPs by > 50 % in uncleaned matrices.

Practical Applications and Benefits

• Simultaneous analysis of CPs and PCBs in one run
• Reduced sample preparation time due to high selectivity
• Robust quantification in complex food matrices
• Streamlined data processing with TraceFinder software

Future Trends and Potential Applications

Expansion of GC-Orbitrap HRMS for broader halogenated POP screening. Further automation of sample preparation and data handling to support high-throughput environmental and food safety monitoring. Potential application in regulatory compliance and contaminant surveillance.

Conclusion

The Q Exactive GC Orbitrap GC-MS/MS provides superior sensitivity, selectivity and dynamic range for SCCP and MCCP analysis in food matrices. Full-scan high-resolution acquisition enables reliable simultaneous quantification of CPs and PCBs, offering a streamlined approach for multi-residue POP monitoring.

References

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2. Stockholm Convention on Persistent Organic Pollutants. UNEP-POPS-COP.8/14. 2017.
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4. Reth M. et al. Anal. Bioanal. Chem. 2004;378:1741–1747.