Orbitrap GC-MS: An Opportunity to Help Address the Challenges of Chlorinated Paraffins Analysis

Importance of Chlorinated Paraffins Analysis

Chlorinated paraffins (CPs) are a diverse group of high-production synthetic compounds used in flame retardants, plasticizers, hydraulic fluids and metalworking lubricants. Due to their complex isomeric composition, environmental persistence and bioaccumulative nature, CPs—especially short-chain CPs (SCCPs)—have become regulated contaminants under international treaties. Reliable detection and quantification in food and environmental samples are critical for public health and regulatory compliance.

Objectives and Study Overview

This study by the European Union Reference Laboratory for Dioxins and PCBs evaluates the Thermo Scientific Q Exactive GC Orbitrap GC-MS/MS platform for the analysis of SCCPs and medium-chain CPs (MCCPs) in food matrices. It aims to demonstrate enhanced selectivity, accurate mass measurement, and the capacity to simultaneously monitor CPs and other persistent organic pollutants (POPs) such as PCBs.

Methodology and Instrumentation

Cp analysis typically relies on gas chromatography with analogue detectors or low-resolution mass spectrometry; however, co-elution and chemical interferences limit specificity. This work employs negative chemical ionization (NCI) at 60,000 resolving power in full-scan mode (50–630 m/z), coupled to a short TraceGOLD TG-SilMS column with a fast temperature ramp (50 °C/min) to produce rapid (under 10 minutes) chromatograms. Extracted ion chromatograms with a ±3 ppm window allow discrimination of isobaric CP ions and suppression of interfering compounds.

Used Instrumentation

• Thermo Scientific Q Exactive GC Orbitrap GC-MS/MS system
• ExtractaBrite Ion Source (EI and NCI compatible)
• Advanced Quadrupole Technology (AQT) for mass selection
• Curved Linear Ion Trap (C-Trap) and Orbitrap mass analyzer (up to 120,000 FWHM)
• HCD cell for MS/MS characterization

Main Results and Discussion

High-resolution accurate mass (HRAM) data dramatically improves selectivity over nominal-mass instruments. In salmon samples, closely spaced CP homologues (C10–C13) were resolved into distinct isomer groups, revealing characteristic chromatographic ‘‘humps’’ that could be deconvoluted into C10H15Cl6 through C13H19Cl8 series. Quantification across 25–10,000 ng/g fat showed linear responses (RSD ≤ 4%) without internal standards. Comparison of farmed and wild salmon highlighted differing CP patterns, suggesting potential for geographical fingerprinting. Spiked PCB mixtures did not compromise CP quantitation, and interferences were readily identified and excluded.

Benefits and Practical Applications of the Method

• Sub-ppm mass accuracy and high resolving power ensure unambiguous identification of CP homologues.
• Simultaneous detection of CPs, PCBs, and other halogenated POPs in a single injection increases laboratory throughput.
• Rapid analysis times with minimal sample preparation expand routine monitoring capacity.
• Isomer-level information enables regional origin assessments and targeted risk evaluation.

Future Trends and Possibilities

Advances in HRAM GC-MS will support comprehensive POP surveillance programs, combining data-rich profiling of CPs with multiresidue screening of emerging contaminants. Integration with multidimensional GC and machine-learning algorithms could further refine isomer fingerprinting. Expanded environmental and food-chain studies will benefit from standardized high-resolution approaches, improving risk assessments and policy decisions.

Conclusion

The Q Exactive GC Orbitrap GC-MS/MS platform addresses long-standing challenges in chlorinated paraffin analysis by delivering high sensitivity, selectivity, and accurate mass capability in a streamlined workflow. Its capacity for simultaneous multi-pollutant quantitation and isomer-specific resolution offers a robust tool for regulatory laboratories and environmental research.