Short Chain Chlorinated Paraffins (SCCP) Analysis Using Negative Chemical Ionization (CI) and Low Energy EI by High-Resolution 7250 GC/Q-TOF

Importance of the Topic

Short-chain chlorinated paraffins (SCCPs) pose significant environmental and health concerns due to their persistence, bioaccumulation, and widespread industrial use as flame retardants and lubricant additives. Accurate analysis of SCCPs is critical for environmental monitoring and regulatory compliance, yet challenging because of their complex mixtures and similar mass spectra.

Objectives and Study Overview

This study evaluates the performance of an Agilent 7250 GC/Q-TOF system using two complementary ionization modes: negative chemical ionization (NCI) and low‐energy electron ionization (LE‐EI). The goal is to compare selectivity, sensitivity, and quantified accuracy of SCCP congeners across different chlorine contents.

Used Instrumentation

• Agilent 7890B gas chromatograph with 30 m×0.25 mm DB-5ms UI capillary column
• Agilent 7250 GC/Q-TOF equipped with exchangeable NCI and LE‐EI sources
• Negative CI mode with methane reagent gas at 40%
• Low energy EI at 22 eV electron energy
• MassHunter Quantitative and Qualitative Analysis software v10

Main Results and Discussion

In NCI mode, SCCP spectra showed minimal fragmentation, dominating [M]− and [M−HCl]− ions. This enabled highly specific extracted ion chromatograms (EICs) for congeners ranging C10–C13 with 5–8 chlorines. Quantification covered 71–93% of mixture components depending on chlorine content.
In LE‐EI at 22 eV, increased fragmentation allowed detection of low‐chlorine congeners (e.g., C10Cl4) with improved sensitivity. Calibration curves achieved accurate quantitation consistent with NCI results. The combination of both modes provided complementary coverage across all congeners.

Benefits and Practical Applications

• High selectivity in NCI for heavy chlorinated SCCPs
• Enhanced sensitivity in LE‐EI for low‐chlorine congeners
• Comprehensive profiling of SCCP mixtures in environmental and industrial samples
• Reliable quantitation using pure congener standards and software calibration features

Future Trends and Opportunities

Further development could include automation of congener assignment, integration with high‐throughput sample preparation, and expansion to medium and long‐chain chlorinated paraffins. Advances in data processing and machine learning may improve deconvolution of isomeric spectra.

Conclusion

The dual‐mode GC/Q-TOF approach offers a robust solution for SCCP analysis, combining NCI’s selectivity with LE‐EI’s sensitivity. This methodology enhances congener coverage and quantitation accuracy, supporting environmental monitoring and regulatory efforts.

Reference

1. Persistent Organic Pollutants Review Committee, Short‐chained chlorinated paraffins: Risk Profile Document UNEP/POPS/POPRC.2, 2017.
2. Houde M. et al., Bioaccumulation and Trophic Magnification of SCCPs in Food Webs from Lake Ontario and Lake Michigan, Environ. Sci. Technol. 42(10):3893–3899, 2008.
3. Gao W. et al., Quantification of SCCPs by GC-QTOF-MS, J. Chromatogr. A 1452:98–106, 2016.