Volatile Organic Compound Screening in Soil Using SPME-GC/MS

Importance of the Topic

The rapid field screening of volatile organic compounds (VOCs) in soil is essential for timely decision-making in environmental analysis, contamination site assessment, and remediation planning. Deploying portable, solvent-free methods accelerates sample triage and reduces reliance on centralized laboratories.

Aim and Study Overview

This application note demonstrates the coupling of solid phase microextraction (SPME) with a portable GC/MS system to identify and estimate relative concentrations of VOCs directly in soil samples. The goals were to validate the approach for rapid in-field screening of a standard reference soil spiked with 42 VOCs and to compare results against existing EPA Screening Method 3815.

Methodology and Instrumentation

Solid phase microextraction was performed using a Custodion® syringe equipped with a 65 µm PDMS/DVB fiber. Five grams of spiked soil were mixed with 5 mL water and 25 % NaCl to enhance VOC partitioning. After a shaking/exposure cycle of 50 s repeated five times (~5 min total), the fiber was desorbed in the injection port of a Torion® T-9 portable GC/MS.

• GC column: MXT-5 capillary (5 m × 0.1 mm ID, 0.4 µm film)
• Carrier gas: Helium, constant flow (~0.2 mL/min)
• Oven program: 40 °C to 280 °C at 2 °C/s (total runtime <2.5 min)
• MS detector: Toroidal ion trap, mass range 41–500 Da, ~10 Hz scan rate, electron impact ionization

Results and Discussion

Under two minutes of analysis time, 37 of the 42 spiked VOCs were positively identified using an on-board deconvolution library. Co-eluting pairs (e.g., 1,3-dichloro-1-propene isomers with toluene and trichloroethane) were resolved by automated library matching. Five highly volatile analytes (e.g., acetone, methyl halides) were not detected, likely due to losses during handling or SPME discrimination.

Benefits and Practical Applications

The SPME-GC/MS approach delivers:

• Near real-time VOC profiling in field conditions
• Elimination of organic solvents and complex lab infrastructure
• Guidance for targeted sampling and remediation strategies
• Reduced analysis costs by screening out samples that require detailed lab work

Future Trends and Applications

Advances may include integration of more extensive compound libraries, improved deconvolution algorithms, miniaturized detectors, and connectivity for remote data review. Such developments will further streamline environmental monitoring and support automated decision-support systems.

Conclusion

The combined Custodion SPME and Torion T-9 portable GC/MS workflow enables fast, reliable identification of soil VOCs on site. Screening results inform sample selection and reduce laboratory workload, offering a powerful tool for environmental scientists and field technicians.

References

1. EPA SW-846 Method 3815 Screening Solid Samples for Volatile Organics, Revision 0, February 2007.
2. Zhang Z.; Pawliszyn J. Analysis of organic compounds in environmental samples by headspace solid phase microextraction. Journal of High Resolution Chromatography 1993, 16(12), 689–692.