Analysis of Persistent Organic Pollutants in Complex Matrices by Gas Chromatography—High Resolution Time-of-Flight Mass Spectrometry (GC-HRT)

Significance of the Topic

The analysis of persistent organic pollutants (POPs) such as PCBs, PCDD/Fs and PBDEs is critical due to their environmental persistence, bioaccumulation and associated health risks. Regulatory restrictions demand reliable monitoring of these halogenated compounds in environmental and biological matrices. High resolution mass spectrometry coupled with gas chromatography offers enhanced selectivity to overcome challenges posed by complex sample backgrounds and low analyte concentrations.

Objectives and Study Overview

This study evaluates the performance of gas chromatography–high resolution time-of-flight mass spectrometry (GC-HRT) for comprehensive detection of POPs in sediment and fish tissue. While targeting various PCB congeners, the investigation also uncovers untargeted classes including PCDD/Fs and PBDEs. The goal is to demonstrate high resolving power, accurate mass measurement and effective separation of coeluting isomers and fragment ions.

Methodology

Environmental samples were extracted with isooctane, followed by direct injection into an Agilent 7890 GC with a Restek Rxi-5Sil MS column. Data acquisition used both high resolution (R≈25 000) and ultra-high resolution (R≈50 000) modes of the Pegasus GC-HRT, enabling selective ion extraction from complex chromatograms. Spectral acquisition was set at 3 spectra/s across m/z ranges optimized for each resolution mode.

Used Instrumentation

• Gas Chromatograph: Agilent 7890 with 7693 autosampler
• Column: Restek Rxi-5Sil MS, 60 m × 0.18 mm ID, 0.10 µm film
• Injection: Splitless, 1 µL at 300 °C
• Oven Program: 80 °C (1 min) to 160 °C @ 30 °C/min to 300 °C @ 3 °C/min (4 min hold)
• Carrier Gas: Helium, constant flow 1.00 mL/min
• Mass Spectrometer: LECO Pegasus GC-HRT; Electron ionization source; Folded Flight Path™
• Resolution Modes: High (R=25 000) and Ultra-High (R=50 000) at m/z 218.985
• Spectral Range: High resolution m/z 50–1000; Ultra-high resolution m/z 200–600
• Acquisition Rate: 3 spectra/second; Calibration with PFTBA

Main Results and Discussion

AIC and XIC traces reveal clear separation of multiple PCB congeners alongside other POP classes (e.g., HCB, DDMU, PeCDF, BDE 47, CB 180). High resolution mode allowed extraction of target ions from a dense ion matrix, while ultra-high resolution provided baseline resolution of key fragment ions such as [M-Cl2+2]+ for CB 180 and [M-Br2]+ for BDE 47. Mass accuracy for detected POPs consistently fell within ±1 ppm.

Benefits and Practical Applications

The GC-HRT approach offers rapid, high-selectivity analysis with minimal sample cleanup. Its high resolving power enhances confidence in compound identification and quantitation in complex environmental and biological samples. Laboratories performing QA/QC, regulatory monitoring or research on POPs can leverage this platform for both targeted screening and non-targeted discovery of emerging contaminants.

Future Trends and Potential Applications

Advancements may include coupling GC-HRT with multidimensional separations or ion mobility for deeper compound coverage. Integration of non-targeted data processing and chemometric tools will facilitate broader environmental screening. The technology may also be extended to novel halogenated species and transformation products, supporting comprehensive contaminant surveillance.

Conclusion

This work demonstrates that GC-HRT delivers superior selectivity and mass accuracy for comprehensive POP analysis in complex matrices. Operation in ultra-high resolution mode enables baseline separation of coeluting fragments, making the instrument a versatile tool for environmental and toxicological investigations.

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