Discovery of Environmental Pollutants at an Electronic Waste Recycling Facility by Pegasus GC-HRT 4D

Significance of the Topic

Electronic waste (e-waste) generation has doubled over a few years, posing serious environmental and health risks due to the release of legacy and newly formed organic contaminants. Unregulated recycling sites, especially in developing regions, can emit toxic substances derived from flame retardants, heavy metals and by-products formed during improper processing. A comprehensive, high-resolution analytical approach is essential to uncover both known and unknown hazardous compounds in these complex matrices.

Study Objectives and Overview

The study aimed to apply comprehensive two-dimensional gas chromatography combined with high-resolution time-of-flight mass spectrometry (GC×GC-HRT) to workshop floor dust and electronic shredder waste. Key goals included non-target screening for persistent organic pollutants, tentative identification of emerging contaminants and chemical characterization of complex unresolved regions.

Methodology and Instrumentation

Samples were extracted from workshop dust and shredded plastic waste after metal recovery. A 1 µL aliquot was injected cold splitless into an Agilent 7890B GC equipped with a dual-stage cryogenic modulator and Gerstel MPS2 autosampler. Two orthogonal columns (non-polar Rtx-Dioxin2 and mid-polar Rxi-17SilMS) provided enhanced separation over a temperature program spanning 80–340 °C. The transfer line and inlet were held at 340 °C. Mass analysis used a LECO Pegasus GC-HRT 4D operating in electron ionization mode, mass range m/z 15–1000, resolving power of 25,000 (FWHM) and acquisition rates of 5 spectra/s (first dimension) and 100 spectra/s (second dimension). Continuous infusion of perfluorotributylamine enabled post-run calibration for sub-ppm mass accuracy. Data processing and peak deconvolution were carried out with ChromaTOF-HRT software.

Main Results and Discussion

High-resolution chromatograms revealed thousands of peaks per sample. Library searches (NIST14, Wiley10) combined with accurate mass (<1.5 ppm) and isotope pattern matching allowed tentative identification of numerous halogenated and non-halogenated compounds.

• Legacy flame retardants and halogenated aromatics such as polychlorinated biphenyls, polychlorinated naphthalenes, polybrominated diphenyl ethers and Dechlorane Plus were detected with varying intensities across samples.
• Novel mixed bromo-chloro diphenyl ether congeners were putatively identified by extracting m/z 281.9263, revealing at least five isomers with formula C12H6Br3ClO.
• Complex unresolved regions separated in the second chromatographic dimension uncovered hundreds of petroleum biomarkers including hopanes, steranes, hopanoic acids, benzohopanes and mono-, di-, tri-aromatic secohopanoids. Characteristic fragments (e.g., m/z 191.1794 for hopanes, m/z 365.3203 for monoaromatic 8,14-secohopanoid) supported their identification.

These findings illustrate the power of GC×GC-HRT to resolve and identify both regulated contaminants and unexpected compounds formed or concentrated in recycling environments.

Benefits and Practical Applications

The comprehensive workflow enables:

1. Non-target discovery of emerging toxins without authentic standards.
2. High confidence in elemental composition assignments via sub-ppm mass accuracy and isotope matching.
3. Differentiation of co-eluting analytes in highly complex matrices.
4. Support for environmental monitoring, regulatory compliance and risk assessment at recycling facilities.

Future Trends and Potential Applications

Advances in GC×GC-HRT could include integration of automated suspect-list screening, machine learning-driven pattern recognition and expanded high-resolution libraries. Coupling with complementary techniques such as ion mobility spectrometry could further enhance separation. Broader application to soil, air and biota around e-waste sites will deepen understanding of pollutant fate and transport.

Conclusion

The combination of multidimensional chromatography with high-resolution mass spectrometry provides an unmatched approach for the comprehensive characterization of complex environmental samples. GC×GC-HRT revealed both known and previously unreported organic pollutants in e-waste facility dust and shredder residues, highlighting its value for environmental and public health studies.

References

1 Baldé C.P. et al. The global e-waste monitor – 2014, United Nations University, 2015.
2 Ma J. et al. Environ Sci Technol. 2008, 42, 8252–8259.
3 Wen S. et al. Environ Sci Technol. 2008, 42, 4202–4207.
4 Robinson B.H. Sci Total Environ. 2009, 408, 183–191.
5 Oliveira C.R. et al. Org Geochem. 2012, 53, 131–136.