The Analysis of Volatile Organic Compounds by Purge and Trap on the SPB™-624 Column

Importance of the Topic

Volatile organic compounds (VOCs) represent a broad class of environmental contaminants found in air, soil and water. Reliable quantitation of trace VOCs is essential for regulatory compliance, risk assessment and environmental remediation. Purge and trap combined with gas chromatography–mass spectrometry (GC–MS) offers high sensitivity and selectivity, making it a cornerstone in environmental analytical laboratories.

Objectives and Study Overview

This application note evaluates the performance of the SPB-624 capillary column in purge-and-trap GC–MS analysis of VOCs. The study aims to demonstrate:

• Chromatographic resolution of key VOCs without cryogenic focusing
• Linearity and precision across a wide on-column mass range (50–1000 ng)
• Operational advantages for high-throughput analysis

Methodology and Instrumentation

A 50 ng VOC standard in 5 mL water was processed using a Tekmar LSC 2000 purge-and-trap system equipped with a Vocarb™ 3000 trap. Conditions included an 11 min purge at 40 mL/min (ambient temperature), a 3 min dry purge, desorption at 250 °C for 4 min, and bake at 280 °C for 10 min. An SPB-624 fused-silica capillary column (75 m × 0.53 mm i.d., 3.0 µm film) was installed on a jet-separator GC–MS. The oven program ran from 40 °C (2 min hold) to 65 °C at 5 °C/min, then to 155 °C at 12 °C/min, and finally to 210 °C at 25 °C/min. Helium was the carrier gas at 10 mL/min, and MS scanned from m/z 35–350.

Main Results and Discussion

The SPB-624 column achieved sharp peaks for a six-component VOC mixture even with a low initial oven temperature and short hold time. Ambient-temperature focusing was sufficient to avoid peak broadening and tailing, eliminating the need for cryogenic cooling. The column exhibited excellent chromatographic efficiency and resolved all target analytes with clear baseline separation.
Calibration over 50–1000 ng on-column yielded good linearity for most of the 94 compounds tested. Relative standard deviations (%RSD) were typically below 10%, demonstrating robust precision. The wide calibration range minimizes re-analysis due to samples outside the working range.

Benefits and Practical Applications

• No cryogenic cooling requirement simplifies hardware and reduces operational costs
• High flow capacity of 0.53 mm i.d. supports rapid desorption and narrow injection bands
• Extended linear range up to 1000 ng reduces sample dilutions and reruns
• Enhanced throughput for routine environmental screening and regulatory monitoring

Future Trends and Prospects

Advances in stationary phases and purge-trap automation will continue to streamline VOC analysis. Integration with high-resolution mass spectrometry or tandem MS detection can improve compound identification and lower detection limits. Emerging passive sampling and direct-injection interfaces may further increase laboratory efficiency while maintaining analytical performance.

Conclusion

The SPB-624 column, when paired with purge-and-trap GC–MS, delivers high sensitivity, precision and throughput for environmental VOC analysis. Its ability to focus analytes at ambient temperature and support a broad calibration range makes it a practical choice for routine air, soil and water monitoring.

Reference

Supelco Application Note 160: The Analysis of Volatile Organic Compounds by Purge and Trap on the SPB™-624 Column, Sigma-Aldrich Co.