Analysis of Trace Persistent Organic Pollutants (POPs) in Dust Using a Novel Multi-Mode Ionization Source and High ResolutionTime-of-Flight Mass Spectrometry

Importance of the Topic

Household and office dust accumulate a wide variety of persistent organic pollutants (POPs), making them a valuable matrix for non-invasive assessment of human exposure. Trace-level detection and identification of these compounds is essential for environmental monitoring, public health studies, and regulatory compliance.

Objectives and Study Overview

1. Evaluate a novel multi-mode ionization source coupled with high-resolution time-of-flight mass spectrometry (HRTOFMS) for comprehensive analysis of dust.
2. Apply enhanced two-dimensional gas chromatography (GC×GC) and HRTOFMS to screen and identify trace POPs in complex dust samples.

Methodology

Samples of NIST SRM 2585, office dust, and household dust were prepared by extracting 0.10 g of material with 3 mL organic solvent. The protocol involved vortex mixing, sonication, centrifugation, and filtration to obtain analyte-rich supernatants. GC×GC separations employed an Agilent 7890B equipped with a LECO dual-stage quad jet modulator. A temperature program ramped from 70 °C to 300 °C, and helium was used as carrier gas. The multi-mode source operated in electron ionization (EI), positive chemical ionization (PCI), and electron-capture negative ionization (ECNI) modes using methane as reagent gas. HRTOFMS data were acquired at resolution ≥ 25 000 (m/z 219) with mass accuracy ≤ 1 ppm, and acquisition rates of 125 spectra per second.

Instrumentation Used

• Gas chromatograph: Agilent 7890B with LECO dual-stage quad jet modulator.
• Mass spectrometer: LECO Pegasus HRT+ 4D high-resolution time-of-flight.
• Columns: HP-5MS UI (30 m × 0.25 mm × 0.25 µm) as primary; BPX-50 (0.60 m × 0.10 mm × 0.10 µm) as secondary.
• Ion sources: EI at 250 °C; PCI/ECNI at 165 °C.
• Carrier gas: Helium at 1.0 mL/min constant flow.

Key Results and Discussion

High-resolution mass spectra and comprehensive two-dimensional contour plots enabled confident detection of halogenated flame retardants, chlorinated pesticides, and other POPs. Representative compounds identified in SRM 2585 included trans-chlordane, cis-chlordane, BDE-99, TDCPP, sumithrin isomers, permethrin isomers, and cyfluthrin isomers, with library match scores above 800/1000 and mass errors typically < 1 ppm. Comparative analysis showed the highest concentrations in the NIST reference material, followed by office and household dust.

Benefits and Practical Applications

• Simultaneous multi-mode ionization enhances detection of diverse chemical classes without separate targeted runs.
• High-resolution accurate mass measurements improve confidence in compound identification and reduce false positives.
• GC×GC contour plots offer visual guidance for non-target screening and discovery of unknown POPs.
• Approach is suitable for routine monitoring in environmental, occupational, and indoor air quality studies.

Future Trends and Applications

Integration of multi-mode ionization HRTOFMS with advanced data analytics and machine learning will further enable comprehensive non-target screening workflows. Application to additional matrices such as soil, sediment, and biological tissues can broaden environmental and human exposure assessments. Miniaturization and automation of sample preparation and data processing will facilitate high-throughput routine analyses.

Conclusion

The combination of a novel multi-mode ionization source with GC×GC and high-resolution time-of-flight mass spectrometry provides a powerful platform for trace-level analysis of POPs in dust. This workflow delivers high confidence in compound identification, comprehensive coverage of chemical classes, and clear visualization of complex data, supporting environmental monitoring and human exposure studies.

References

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