Petrol Range Organics In Soils, Sludges And Wastewaters by Headspace GC-MS

Significance of the Topic

Environmental contamination by petrol hydrocarbons poses risks to ecosystems and human health. Reliable quantification of petrol range organics (PRO) in soils, sludges and wastewaters is essential for regulatory compliance, pollution assessment and remediation monitoring.

Study Objectives and Overview

This work aimed to develop and validate a headspace GC-MS procedure for specific and rapid determination of PRO, including aromatic, aliphatic and oxygenated additives, to overcome the non-selective biases of traditional integration methods.

Methodology and Instrumentation

• Sample preparation:
  • Soils: 2 g sample, 2 mL methanol, 2 mL matrix modifier and toluene-d8 internal standard in 20 mL vials
  • Waters: 2 mL sample with toluene-d8 internal standard in 20 mL vials
• Headspace conditions: 80 °C incubation for 3.5 min, 750 rpm agitation, syringe at 100 °C, 400 µL injection
• Analysis: Agilent 6890 GC coupled with 5973 MSD in full-scan mode, 4-min runtime
• Autosampler: Focus Robotic Sample Processor with 96-vial capacity, no transfer line for enhanced reproducibility

Main Results and Discussion

• Chromatographic separation resolved 16 targeted compounds—MTBE, benzene, toluene, xylenes and C6–C10 alkanes—within 4 minutes
• Soil spikes at three levels exhibited mean recoveries near 100%, RSDs typically below 5%, and LODs as low as 0.02–0.20 ppm
• Water spikes at two levels yielded RSDs under 3% and sub-ppm detection limits
• Headspace sampling eliminated flow-related variability and delivered rapid, reproducible injections

Benefits and Practical Applications

• Selective quantification of petrol hydrocarbons reduces false positives from non-petroleum interferences
• Rapid analysis throughput (4 min per run) supports high sample volumes and fast reporting
• Low detection limits and strong recoveries meet stringent environmental and regulatory standards
• Automation and minimal sample preparation streamline laboratory workflows for QA/QC and research

Future Trends and Possibilities

• Expansion to broader volatile and semi-volatile compound screening using headspace techniques
• Coupling with high-resolution mass spectrometry for enhanced selectivity and non-target analysis
• Development of portable headspace GC-MS systems for in-field monitoring
• Application of data analytics and machine learning to interpret complex environmental datasets

Conclusion

The validated headspace GC-MS method, combining the Focus autosampler with the Agilent 6890 GC and 5973 MSD, delivers fast, accurate and reproducible measurement of petrol range organics in soils and waters. Its high performance, speed and low detection limits make it a superior alternative to traditional PRO methods.