Fast Analysis of 140 Environmental Compounds by GC/MS/MS

Importance of the topic

The reliable and rapid quantification of persistent organic pollutants such as pesticides, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) is critical for environmental monitoring, regulatory compliance and human health assessment. Traditional GC-ECD methods require lengthy chromatographic separations and multiple injections for comprehensive coverage of these compound classes. Implementing GC/MS/MS with dynamic multiple reaction monitoring (dMRM) can significantly accelerate analysis while maintaining selectivity and sensitivity.

Objectives and study overview

The primary aim of this work was to develop and validate a single, fast GC/MS/MS method capable of quantifying 140 environmental analytes (24 PAHs, 24 pesticides and 92 PCBs) in air and precipitation extracts. The study compared results to historical data obtained by GC-ECD to demonstrate equivalency in quantification and to measure time savings.

Methodology and instrumentation

Sample preparation and fractionation followed established protocols using XAD-2 resins for air and precipitation collection, with subsequent partitioning into hexane and hexane/DCM fractions. Key instrumental parameters included:

• Instrument: Agilent 8890 GC coupled to 7000D triple quadrupole MS
• Injection: MMI inlet at 280 °C, pulsed splitless mode (25 psi until 0.5 min)
• Column: HP-5MS, 30 m × 0.25 mm, 0.25 µm film
• Carrier gas: Helium at 1.0 mL/min constant flow
• Oven program: 60 °C (1 min), ramp 40 °C/min to 170 °C, then 10 °C/min to 310 °C (3 min hold)
• MS conditions: Transfer line 320 °C, 425 MRM transitions across 181 groups

dMRM transitions were optimized using the Agilent P&EP database, literature values and Optimizer software. Each analyte was monitored with one quantifier and one qualifier transition.

Key results and discussion

The unified GC/MS/MS method achieved full quantification of all 140 analytes in under 21 minutes per injection, representing a ~17× speed improvement compared to separate GC-ECD runs (approximately 6 hours total). Results for environmental samples (concentrations 3–675 ppb) matched historical GC-ECD data, confirming accuracy. Total ion chromatograms demonstrated clear peak separation and high signal-to-noise ratios for PAHs, pesticides and PCBs within the shortened runtime.

Benefits and practical applications

• Significant reduction in instrument and analyst time
• Improved peak identification confidence via MS/MS transitions
• Single-run quantification streamlines environmental monitoring workflows
• Low-ppb detection limits suitable for regulatory compliance and research

Future trends and opportunities

Expanding this approach to include non-target screening and high-throughput automated sample preparation could further enhance environmental surveillance. Integration with online sampling and data-processing algorithms may enable real-time pollutant tracking. The method platform is adaptable to emerging contaminants and complex matrices beyond air and precipitation.

Conclusion

The transition from GC-ECD to GC/MS/MS dMRM provides dramatic time savings without compromising sensitivity or quantification accuracy for a broad suite of 140 environmental pollutants. This unified method enhances laboratory efficiency, confidence in results, and supports high-throughput environmental analysis.

References

1. Zohair A. et al. Residues of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides in organically-farmed vegetables. Chemosphere 63(4):541–553 (2006).