Volatile Organics US EPA Method 502.2 Rtx®-502.2

Importance of the topic

Controlling and monitoring volatile organic compounds (VOCs) in environmental and industrial contexts is essential for public health, regulatory compliance and quality assurance. The US EPA Method 502.2 provides a standardized approach for the reliable detection and quantification of a broad range of halogenated and aromatic solvents in water matrices.

Objectives and overview

The main goal of this application note is to demonstrate the performance of the Restek Rtx-502.2 capillary column in conjunction with a purge-and-trap concentrator and a tandem PID/Hall electrolytic conductivity detector. A total of 71 target compounds are resolved in a single 30-minute analysis, meeting sensitivity requirements (20 ppb) for environmental monitoring.

Methodology and instrumentation

Samples of deionized water spiked at 20 ppb (with selected compounds at 40 ppb) are processed using a Tekmar LSC-3000 Purge and Trap system with a Vocarb 3000 trap. Purge parameters:

• Purge time: 11 min at 40 mL/min
• Dry purge: 1 min at 40 mL/min (MCS off)
• Desorb preheat: 245 °C; Desorb: 250 °C for 2 min; Bake: 260 °C for 8 min

The gas chromatograph is a Finnigan 9001 configured with a 75 m × 0.45 mm ID, 2.55 µm Rtx®-502.2 column. Carrier gas is helium at 9 mL/min (constant pressure). Oven program:

• 35 °C hold 6 min to 115 °C @ 11 °C/min, hold 7 min
• to 130 °C @ 7 °C/min, no hold
• to 220 °C @ 9.2 °C/min, hold 4 min

Used instrumentation

• Purge-and-trap: Tekmar LSC-3000 with Vocarb 3000 trap
• Gas chromatograph: Finnigan 9001 GC
• Column: Rtx-502.2, 75 m × 0.45 mm ID, 2.55 µm (cat. # 10986)
• Detectors: µGold Tandem PID/Hall 2000 electrolytic conductivity detector
• Reference standards: 502.2 Cal2000 MegaMix™, Calibration Mix #1A, Internal Standard Mix #2, plus individual compounds

Main results and discussion

The method achieved baseline separation for all 71 analytes within a 30-minute run. Key halogenated alkanes, alkenes, and aromatic compounds were detected with clear peak shapes and minimal co-elution. The dual detection scheme (photoionization and electrolytic conductivity) allowed for enhanced sensitivity and confirmation of halogen content.

Benefits and practical applications

• Comprehensive coverage of regulatory VOCs in a single injection
• Low detection limits (20 ppb) suitable for drinking water monitoring
• High throughput with automated purge-and-trap sample preparation
• Reliable identification via dual-detection confirmation

Future trends and applications

Advances in microtrap materials and portable GC systems may further streamline field analysis of VOCs. Integration with mass spectrometry and software-driven data processing will enhance compound identification and quantification. Development of rapid screening kits and on-site sensors could reduce analysis time and costs.

Conclusion

The Restek Rtx-502.2 column coupled with a purge-and-trap concentrator and µGold Tandem PID/Hall detector provides a robust solution for EPA Method 502.2. This workflow delivers high resolution, sensitivity, and throughput needed for environmental and industrial VOC monitoring.

Reference

• US EPA Method 502.2: Volatile Organics by Purge-and-Trap GC
• Restek Corporation Application Note: Rtx®-502.2 Column Performance (cat.# 10986)