Determination of Volatile Organic Compounds in Soil and Sediments

Significance of the Topic

Detection and quantitation of volatile organic compounds in soils and sediments underpin effective hazardous site management, remediation planning, and regulatory compliance. Methods that combine ease of operation, low carryover, and high sensitivity are essential to meet stringent requirements of protocols like HJ642-2013.

Objectives and Study Overview

This study evaluates the performance of an Agilent combined platform—7697A static headspace sampler, 8890 GC, and 5977B GC/MSD with a high-efficiency source (HES)—for targeted analysis of 36 VOCs in quartz sand and spiked soil samples following HJ642-2013 guidelines. Key performance metrics include linearity, limits of detection (LOD/LOQ), precision, and recovery.

Methodology and Instrumentation

• Calibration and standards preparation involved spiking matrix modifier (acidified, salt-saturated water) and quartz sand with the VOC working mixture and internal standards across 2–100 μg/L (10–500 μg/kg in matrix).
• Low-level tests (0.05–5 μg/L) were performed to assess minimum detection limits using surrogates at 5 μg/L.
• Instrumentation parameters: headspace equilibration at 80 °C for 35 minutes with sample shaking; GC oven ramping from 40 °C to 200 °C; MSD in SIM mode (m/z 35–300) with GF 0.1 or 1.0 for low-level analysis.

Instrumentation

• Agilent 7697A static headspace sampler (20 mL vial manifold, PTFE/silicone septa)
• Agilent 8890 GC with split/splitless inlet
• Agilent 5977B GC/MSD with high-efficiency source (HES)
• DB-624 column (60 m × 0.25 mm, 1.4 μm)
• Agilent MassHunter software for acquisition and quantitative analysis

Key Results and Discussion

• MSD tune and performance met all HJ642-2013 requirements in HES mode.
• Linearity for 36 VOCs was excellent (R² ≥ 0.995) over 2–100 μg/L; styrene and methylene chloride showed minor deviations but remained within acceptable ranges after background correction.
• Precision (six replicates at 20 μg/L) yielded RSDs of 1.7–4.6%, except styrene at 7%.
• Method LODs and LOQs for real samples ranged from 1.0 to 2.5 μg/kg, matching regulatory demands.
• High-efficiency source improved signal-to-noise by 3–7× versus conventional extractor sources, enabling reliable detection at 100 ppt levels (MDLs 0.03–0.27 μg/kg) with eight replicates at 50 ng/L.

Advantages and Practical Applications

• Automated sample loading and minimal carryover enhance laboratory throughput.
• High sensitivity and low detection limits support accurate quantitation in challenging matrices.
• Compliance with national standards facilitates regulatory reporting and site assessment.
• Robust precision and recovery rates (73–119%) ensure method reliability for QA/QC and environmental monitoring.

Future Trends and Potential Applications

Enhanced MSD operating parameters and further HES optimization may push detection capabilities into sub-ppt ranges. Expanding compound coverage, real-time field deployable platforms, and integration with data analytics will broaden environmental and industrial applications.

Conclusions

The Agilent 7697A/8890/5977B HES-MSD platform meets or exceeds HJ642-2013 criteria, delivering high linearity, precision, sensitivity, and recovery for VOC analysis in soil and sediment. HES significantly enhances detection performance, making this system a versatile solution for regulatory and research laboratories.

References

• US EPA Method 5021, “Volatile Organic Compounds in Soils and Other Solid Matrices using Equilibrium Headspace Analysis,” Revision 0, 1996.
• HJ 642-2013. “Determination of Volatile Organic Compounds in Soil and Sediments—Headspace-GC/MS,” Ministry of Ecology and Environment of the PRC.
• HJ 741-2015. “Determination of Volatile Organic Compounds in Soil and Sediments—Headspace-GC,” Ministry of Ecology and Environment of the PRC.
• Agilent Technologies, “Improved Volatiles Analysis Using Static Headspace, the Agilent 5977B GC/MSD, and a High-Efficiency Source,” Application Note 5991-6539EN, 2016.