Automated Handling Techniques for the Analysis of Elevated Volatile Organic Compound (VOC) Concentrations in Soils Utilizing the Atomx Concentrator/Multimatrix Autosampler

Importance of the Topic

Volatile organic compounds (VOCs) in soils pose significant environmental and health risks when present at elevated concentrations. Accurate quantification of high-level VOCs is critical for regulatory compliance, site remediation, and risk assessment. Traditional manual preparation methods can be labor-intensive and prone to error, leading to sample loss and variability. Automated handling techniques offer improved precision, reduced carryover, and enhanced throughput for environmental laboratories.

Study Objectives and Overview

The primary aim of this work was to evaluate an automated extraction and analysis workflow for high-level VOC soils using the Atomx concentrator/multimatrix autosampler coupled with an Agilent 7890A GC and 5975C MS. Specific goals included comparing automated versus manual methanol extraction efficiency, assessing reproducibility and linearity of target analytes, and quantifying carryover reduction.

Methodology and Instrumentation

Extraction Approach:

• Samples exceeding the 200 µg/kg calibration range were extracted with methanol, diluted in de-ionized water, and purged under USEPA Methods 5035/5030.
• Both 5 g and 7 g soil masses were tested with 10 mL and 7 mL methanol volumes, respectively.

Instrumentation Used:

• Atomx concentrator/multimatrix autosampler with proprietary U-shaped #9 adsorbent trap and Siltek™/PEEK™ sample pathway.
• Agilent 7890A gas chromatograph equipped with a J&W DB-624 column (20 m×0.18 mm×1.0 µm).
• Agilent 5975C inert XL mass selective detector operated in scan mode (m/z 35–300).

Calibration and Data Processing:

• Calibration range: 1–200 ppb in water with 1 mL methanol spike; 50 ppm internal standard delivered at 25 ppb.
• Analysis and quantitation performed with Agilent ChemStation; all compounds exhibited %RSD ≤ 11.4%.

Main Results and Discussion

Carryover Performance:

• After extracting a 20 ppm spiked sand sample, carryover in subsequent blanks was < 0.4%, enabled by automated methanol rinsing of the sample pathway.

Extraction Linearity and Reproducibility:

• Five concentrations (5–100 ppb) yielded linear responses (R² ≥ 0.998) across nine gasoline-range organic compounds for both automated and manual methods.
• Ten replicates at 50 ppb showed < 10% RSD for all compounds, demonstrating excellent precision.
• Comparative recovery at 50 ppb revealed deviations of 83–94% for automated versus manual processes, confirming accuracy.

Benefits and Practical Applications

• Automation reduces manual handling errors, volatile loss, and variability associated with traditional extraction.
• Integration of autosampler and purge-and-trap concentrator shortens sample pathways and improves temperature uniformity.
• High throughput capability supports QA/QC, research, and industrial environmental monitoring.

Future Trends and Potential Applications

Advances in automated sample preparation are expected to extend to multi-matrix workflows, incorporating solid, liquid, and air samples on a single platform. Further integration with data management and on-line calibration will enhance real-time decision making. Improvements in trap materials and solvent compatibility will expand the analyte scope and reduce solvent consumption.

Conclusion

The Atomx concentrator/multimatrix autosampler, combined with an Agilent GC-MS system, provides a robust, accurate, and reproducible solution for high-level VOC soil analysis. Automated methanol extraction significantly decreases carryover and human error while maintaining linearity and precision, thereby boosting laboratory productivity and data quality.

References

1. Jurek, A. Automated Handling Techniques for the Analysis of Elevated VOC Concentrations in Soils Utilizing the Atomx Concentrator/Multimatrix Autosampler. Teledyne Tekmar Application Note, 2009.