Determination of Volatile Organic Compounds in Soil and Sediment by Purge and Trap GC/MS

Significance of the topic

With growing urbanization and industrial activities, volatile organic compounds (VOCs) in soils and sediments present significant environmental and health risks. These pollutants can affect plant and animal life and migrate into air and water, underscoring the need for sensitive, reliable analytical methods.

Objectives and overview of the study

This application note applies China’s HJ 605-2011 method to quantify 65 VOCs in soil and sediment. It demonstrates the performance of an integrated purge-and-trap GC/MS system under defined calibration and validation criteria.

Methodology and procedure

• Calibration standards prepared at 5, 20, 50, 100, and 200 µg/L with internal standards (fluorobenzene, chlorobenzene-d5, 1,4-dichlorobenzene-d4) and surrogate standards.
• Purge-and-trap parameters: 5 mL purge vessel, medium mixing, 11 min purge at 40 mL/min, desorb and bake cycles per optimized conditions.
• GC parameters: Agilent DB-Select 624 UI column, oven program from 38 °C to 240 °C, helium carrier flow 1.5 mL/min.
• MSD parameters: EI ionization, scan acquisition, source temperature 230 °C, quadrupole at 150 °C.

Instrumentation used

• Teledyne Tekmar Atomx XYZ purge-and-trap sampler.
• Agilent 7890B gas chromatograph with DB-Select 624 Ultra Inert column (30 m × 0.25 mm, 1.4 µm).
• Agilent 5977B GC/MSD mass spectrometer operated in scan mode.

Main results and discussion

• Chromatographic separation of 65 VOCs at 50 µg/L with well-resolved peaks, especially for early eluters prone to coelution.
• Linear calibration with R² values from 0.993 to 0.9999 over 5–200 µg/L.
• Precision demonstrated as %RSD of 0.9–12.2% (n=6) at 5 and 20 µg/L levels, meeting method criteria of <20% RSD.
• Limits of detection between 0.2 and 1.6 µg/L for all compounds, with most below 1 µg/L.
• Recovery of 76.1–135.6% for 65 VOCs spiked at 50 µg/L in soil samples.

Benefits and practical applications

The validated purge-and-trap GC/MS workflow provides high sensitivity, robustness, and throughput for environmental monitoring, regulatory compliance, quality control, and research in soil and sediment analysis.

Future trends and potential applications

• Automation of sample preparation and data analysis to increase laboratory efficiency.
• Extension of the method to other complex matrices such as sludge or water.
• Development of rapid screening techniques and miniaturized extraction approaches.
• Integration with high-resolution and tandem mass spectrometry for expanded target analyte coverage.

Conclusion

The combined use of purge-and-trap sampling, gas chromatographic separation, and mass spectrometric detection per HJ 605-2011 delivers a robust analytical solution for the quantitation of 65 VOCs in soil and sediment, with excellent linearity, precision, sensitivity, and acceptable recoveries.

References

1. HJ 605-2011. Determination of Volatile Organic Compounds in Soil and Sediment by Purge and Trap Gas Chromatography/Mass Spectrometry.