CDS 7000C Purge and Trap Performance with CTC PAL Automation

Significance of the Topic

Environmental monitoring of volatile organic compounds in water is essential to ensure safe drinking water and compliance with regulations EPA method compatible analysis. Purge and Trap combined with autosampler automation improves sensitivity and throughput in routine laboratory analysis.

Study Objectives and Overview

The study aims to evaluate the performance of the CDS 7000C Purge and Trap concentrator coupled to a CTC PAL RTC Autosampler under EPA methods 524.2 and 8260 protocols. Fortified water samples with VOC concentrations from 1 to 200 ppb were analyzed to assess linearity reproducibility and carry over.

Methodology and Instrumentation

This work used a Shimadzu GC MS system with a CDS 7000C Purge and Trap concentrator integrated to a CTC PAL RTC Autosampler. Samples were spiked automatically with internal standards and purged at controlled temperature flow and timing. Analytes were trapped adsorptively and thermally desorbed to GC MS for detection. Calibration standards spanned 64 compounds including gaseous analytes and BTEX.

Instrumentation Used

• CDS 7000C Purge and Trap Concentrator
• CTC PAL RTC Autosampler
• Shimadzu GCMS QP 2010
• Rtx VMS capillary column

Main Results and Discussion

Linearity coefficients were better than 0.995 for all compounds with most exceeding 0.999 over 1 to 200 ppb. Response factor RSD for gaseous analytes ranged from 6.8 to 12.4 percent and for BTEX from 2.8 to 8.5 percent. Five day reproducibility of internal standard response produced RSD below 4 percent. Carry over from a high standard to blank did not exceed 1 percent for low boiling VOCs and 2.5 percent for high boiling analytes.

Benefits and Practical Applications

• Fully automated calibration and internal standard addition
• Flexible sample introduction modes
• High throughput by overlapping schedules
• Option for online tap water monitoring with flow cell

Future Trends and Opportunities

Integration of Purge and Trap automation with autosamplers and real time monitoring systems can extend to unattended online analysis. Advances in software scheduling and miniaturized concentrators promise higher sensitivity and reduced sample volumes. Coupling to new detector types may further expand analytical scope.

Conclusion

The combined CDS 7000C P and T concentrator with a CTC PAL autosampler demonstrates excellent linearity reproducibility and low carry over for a broad range of VOCs in water. The high level of automation and throughput makes it a powerful solution for environmental laboratories.

Reference

• EPA Method 8260C SW846 Volatile Organic Compounds by Gas Chromatography Mass Spectrometry
• EPA Method 5030C Purge and Trap for Aqueous Samples