Purgeable Volatile Organic Compounds by GC-MS using Zebron™ ZB-624PLUS™ GC Columns

Importance of the Topic

Volatile organic compounds (VOCs) in water are regulated globally due to their potential health and environmental impacts. Reliable monitoring of these analytes at trace levels is critical for drinking water safety, wastewater treatment, and groundwater assessment. A fast, sensitive, and robust analytical approach is essential for routine environmental testing and regulatory compliance.

Objectives and Study Overview

This application note demonstrates a 15-minute, EPA Method 8260-compliant GC-MS analysis of 74 VOCs in water using the Zebron™ ZB-624PLUS™ column. The study assesses chromatographic separation, detection limits, and reproducibility across 113 injections of diverse sample matrices, including groundwater, wastewater, and sludge.

Methodology and Instrumentation

Two main workflows were combined: purge and trap sample preparation followed by GC-MS analysis.

• Purge and Trap Parameters:
  • Sample temperature: 40 °C
  • Purge time: 11 min
  • Dry purge: 2 min
  • Trap: Supelco® VOCARB 3000 (24920-U) on Tekmar® 3100
  • Desorb: 250 °C for 4 min; bake: 260 °C for 7 min
• GC-MS Conditions:
  • Column: Zebron ZB-624PLUS, 30 m × 0.25 mm × 1.40 µm (Part No. 7HG-G040-27)
  • Inlet: Split 50:1, 1 µL @ 230 °C; Zebron PLUS Straight Z-Liner™ (AG2-0A03-05)
  • Carrier gas: Helium, 0.7 mL/min constant flow
  • Oven: 40 °C (2 min) to 210 °C @ 17 °C/min (3 min)
  • MS transfer line: 250 °C; source: 230 °C; quad: 150 °C; scan 50–550 m/z; solvent delay 1.0 min; Agilent MassHunter® software

Main Results and Discussion

The ZB-624PLUS stationary phase delivered baseline separation of all 74 VOCs within 15 minutes, with excellent peak shapes and low bleed at up to 300/320 °C. A comparative run on a traditional DB-624 column at 260 °C showed rising baseline due to bleed, compromising quantitation of high-boiling components. After 113 injections of complex matrices, the ZB-624PLUS maintained retention times, peak symmetry, and sensitivity at 5 ppb and 0.5 ppb levels, demonstrating high column stability and reproducibility.

Benefits and Practical Applications

• Fast throughput: complete VOC profile in 15 min
• High efficiency: clear separation of polar and nonpolar compounds
• Low bleed: stable baseline at elevated temperatures
• Extended lifetime: robust performance over >100 dirty-matrix injections
• Regulatory compliance: compatible with EPA Methods 524, 624, and 8260

Future Trends and Potential Applications

Advances in stationary-phase technology may further enhance selectivity and thermal stability. Integration with high-resolution mass spectrometry and automated sample handling will improve detection limits and throughput. Miniaturized purge-trap systems and on-site screening platforms are emerging for rapid field analysis.

Conclusion

The Zebron ZB-624PLUS column paired with GC-MS and purge-and-trap extraction offers a robust, high-throughput solution for routine VOC monitoring. Its low-bleed performance, high thermal endurance, and reproducibility make it ideally suited for environmental laboratories seeking reliable compliance with EPA methods.

Reference

1. EPA Method 8260: Volatile Organic Compounds by Gas Chromatography–Mass Spectrometry