Page 7: Guidelines for Canadian Drinking Water Quality: Guideline Technical Document – Carbon Tetrachloride
Part II. Science and Technical Considerations - Continued
Several analytical methods can be used to measure carbon tetrachloride in drinking water, including purge and trap gas chromatography with photoionization and electrolytic conductivity detection or mass spectrometry detection. Carbon tetrachloride can also be measured using liquid-liquid extraction followed by gas chromatography with electron capture detection.
The U.S. EPA has approved three analytical methods for the analysis of carbon tetrachloride in drinking water (U.S. EPA, 2002).
- EPA Method 502.2 Revision 2.1 employs purge and trap capillary gas chromatography with electrolytic conductivity detectors, and has a method detection limit (MDL) range of 0.01-0.02 µg/L.
- EPA Method 524.2 Revision 4.1 uses purge and trap capillary gas chromatography with mass spectrometry detection, and has an MDL range of 0.08-0.21 µg/L.
- EPA Method 551.1 uses liquid-liquid extraction and gas chromatography with linearized electrolytic conductivity detectors and has an MDL range of 0.002-0.006 µg/L (U.S. EPA, 1995). A detection limit range is cited, as multiple detection limits are possible due to variability in reagents, instrumentation, and/or laboratory analyst performance.
In 1985, the U.S. EPA established a practical quantitation limit (PQL) of 5 µg/L for carbon tetrachloride, which was considered the lowest level that could be reliably achieved within specified limits of accuracy and precision (U.S. EPA, 1985). Although the U.S. EPA has not officially adopted a lower PQL, it has identified carbon tetrachloride as a possible candidate for a PQL revision and indicated that more recent data would support selecting a PQL ranging between 2.1 and 2.5 µg/L (U.S. EPA, 2003a).
The American Public Health Association has three equivalent standard methods for the analysis of carbon tetrachloride in water. SM 6200B and SM 6200C are based on purge and trap capillary gas chromatography followed by mass spectrometry or electrolytic conductivity detection, respectively. SM 6200B has an MDL of 0.042 µg/L, and SM 6200C has an MDL of 0.022 µg/L. The minimum quantitation levels, defined as the lowest level that can be quantified accurately, using these methods are 0.168 µg/L and 0.088 µg/L for methods SM 6200B and SM 6200C, respectively. SM 6232 uses liquid-liquid extraction followed by gas chromatography and mass spectrometry detection. A MDL is not reported for this method, due to the possibility of variations in the characteristics of the gas chromatographic system used and interferences present in the solvent (APHA et al., 2005).
Report a problem or mistake on this page
- Date modified: