Low-level Drinking Water Analysis of 1,2,3-Trichloropropane by Purge and Trap Concentration and GC/MS

Significance of the Topic

The analysis of 1,2,3-trichloropropane (TCP) at ultra-trace concentrations in drinking water is critical due to its recognized carcinogenicity and stringent health advisory levels. Accurate, sensitive detection methods ensure regulatory compliance, protect public health, and guide remediation efforts in contaminated groundwater and industrial waste sites.

Objectives and Study Overview

This study aimed to develop and validate a low-level analytical method for TCP in drinking water using purge and trap concentration coupled with single ion monitoring (SIM) GC/MS. Key goals included generating a calibration curve across the ppt range and determining the method detection limit (MDL) in accordance with USEPA Method 524.3.

Methodology and Instrumentation

The analytical system comprised a Teledyne Tekmar Stratum Purge and Trap Concentrator with an AQUATek 100 autosampler interfaced to a Thermo ISQ single quadrupole GC/MS. A Restek Rtx-624 capillary column (20 m × 0.18 mm × 1.0 µm) was used under a temperature program from 45 °C to 240 °C. Helium carrier gas at 1.0 mL/min and a 25:1 split ratio were employed. SIM targeted ions at m/z 110 (quantifier), 112, and 75 (confirmers). Purge and trap parameters included a 6 min purge at 20 °C, 60 mL/min purge flow, and thermal desorption at 250 °C.

Key Results and Discussion

A nine-point calibration from 2.5 to 1000 ppt exhibited excellent linearity (R² = 0.9987). Seven replicate analyses of a 10 ppt TCP spike yielded an average of 9.72 ppt (± 0.17 ppt), corresponding to an MDL of 0.543 ppt (99% confidence). The high sensitivity achieved demonstrates the suitability of SIM purge and trap GC/MS for regulatory monitoring at sub-ppt levels.

Benefits and Practical Applications

• Meets or exceeds regulatory notification levels (e.g., California 0.005 µg/L).
• Enables reliable detection at part-per-trillion concentrations.
• Applicable to routine monitoring and site-specific investigations.
• Automated sample introduction enhances throughput and reproducibility.

Future Trends and Applications

Advancements may include multi-analyte VOC panels, improved trap materials for broader compound classes, integration with real-time data analytics, and miniaturized or portable GC/MS platforms for field deployment. Coupling with isotope dilution and high-resolution MS could further enhance specificity and lower detection limits.

Conclusion

This work validates a robust, highly sensitive TCP assay using purge and trap concentration with SIM GC/MS. The method demonstrates excellent linearity and reproducibility, achieving an MDL of 0.543 ppt, thus providing a powerful tool for safeguarding drinking water quality.

References

• California Department of Public Health. Notification Levels for 1,2,3-Trichloropropane in Drinking Water. 2012.
• USEPA. Method 524.3: Measurement of Purgeable Organic Compounds by Capillary Column GC/MS. Revision 1, 2009.
• USEPA. Emerging Contaminant Fact Sheet: 1,2,3-Trichloropropane. December 2010.