Water for VOC
Impact of Water
Water may be used to rinse the sample containers, in the various sample preparation steps, as well as in the preparation of standards and blanks for the analysis. Gas chromatography (GC) using purge and trap is often used for these analyses.
The following water contaminants may interfere with VOC analysis:
- Organics
Organic molecules, in particular volatile organics (VOC) present in the water used to prepare or analyze the samples may interfere with VOC analysis by contributing a high background and possibly affecting selectivity and sensitivity.
- Chlorine
Some VOCs, in particular aromatic compounds, may react and be degraded by chlorine.
- Bacteria
Bacteria may degrade some VOCs and should therefore be avoided. They may also release some small organics that may interfere with VOC analysis.
Preparing VOC-free water using an activated carbon point-of-use purifier
Ultrapure water was spiked with various VOCs at a concentration of approximately 1 ppb (1 µg/L). The water was passed through a specific activated carbon cartridge (VOC-Pak®) and the concentration of each VOC was measured at the outlet of the cartridge. The VOC analysis was performed using a Purge & Trap GC-MS system. The results are shown here.Conclusion
Ultrapure water should be used for VOC analysis. Using the VOC-Pak® cartridge at the point of use of the water purification system (producing water with a resistivity of 18.2 MΩ.cm at 25 °C and TOC < 5 ppb) can ensure that the VOCs listed in the table are below the analytical quantification limits listed.More Information
- Indoor air quality - VOC: http://www.epa.gov/iaq/voc.html
- VOC in ground water: http://toxics.usgs.gov/definitions/vocs.html
- Health effects of VOC: http://www.dep.state.fl.us/water/drinkingwater/vol_con.htm
- EU Council Directive on the quality of water intended for human consumption: http://ec.europa.eu/environment/water/water-drink/index_en.html
- U.S. National Primary Drinking Water Standards: http://www.epa.gov/safewater/contaminants/index.html
- WHO Guidelines for Drinking-water Quality. 2004: http://www.who.int/water_sanitation_health/dwq/gdwq3/en/index.html
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