Determination of Volatile Organic Compounds (VOCs) in Various Drinking Water Sources by GC/MS

Importance of the Topic

Volatile organic compounds in drinking water pose potential health risks. Public water systems follow EPA method 524.2 to monitor these contaminants, while bottled water is subject to less stringent regulation. Comparing different water sources helps consumers and regulators understand actual exposure and treatment effectiveness.

Goals and Study Overview

The study quantified VOC levels in tap, filtered, well and various bottled waters. Using automated purge and trap concentration coupled with GC/MS, the research evaluated regulated and unregulated sources to assess water quality concerns and the cost benefit of bottled water.

Methodology and Instrumentation

• Sample preparation employed a 25 ml purge volume using a Stratum PTC purge and trap concentrator and AQUATek 100 autosampler
• Gas chromatography was performed on a Varian 431 GC with a 20 m FactorFour VF-624 column
• Mass spectrometry used a Varian 210-MS ion trap detector under EPA performance criteria
• Calibration was linear across the range with relative response factors and a method detection limit study according to EPA method 524.2

Main Results and Discussion

• Tap water contained trihalomethanes, including dibromochloromethane and bromoform up to 29 ppb, plus 2-butanone and tetrahydrofuran from plumbing outgassing
• Filtered water showed lower VOCs, but plastic pitcher components introduced additional contaminants, highlighting the need to rinse filters before use
• Bottled water and untreated well sources exhibited negligible VOC levels, confirming efficient filtration and absence of disinfection byproducts
• Flushing tap water for 15 to 30 seconds reduced most VOCs by over 80 percent, while trihalomethanes remained constant due to their formation at treatment plants

Benefits and Practical Applications

Automated purge and trap GC/MS improves throughput and reproducibility for routine water quality testing. The findings support flushing taps to lower VOC exposure and validate the low VOC content of bottled and well waters for consumer safety.

Future Trends and Opportunities

Future developments may include miniaturized traps, faster cycle times, integration with high resolution MS for broader analyte coverage and real time monitoring. Advances in sample preparation and digital data analysis will further enhance sensitivity and throughput.

Conclusion

This study highlights the presence of disinfection byproducts in tap water and minimal VOC contamination in bottled and well sources. Automated purge and trap GC/MS is a reliable tool for water quality assessment. Recommendations include tap flushing and filter conditioning to reduce consumer exposure.

Reference

EPA method 524.2 Measurement of purgeable organic compounds in water by capillary column gas chromatography mass spectrometry Revision 4.1 1995