NEMI Method Summary

Method Summary Information

Method Number: 6200C Media: WATER
Revision: Standard Methods Online
Method Source: Standard Methods
Subcategory: ORGANIC Analytes in this method
Official Name: Purge and Trap Capillary-Column GC Method
Descriptive Name Volatile organic compounds in Water by Purge and Trap Capillary-Column GC Method
Source Info: Standard Methods Online is jointly produced by the American Public Health Association (APHA), the American Water Works Association (AWWA), and the Water Environment Federation (WEF).
These organizations may be contacted by phone for more information on Standard Methods Online:
APHA: (301) 893-1894
AWWA: (800) 926-7337, (1-303-794-7711, outside U.S. / Canada)
WEF: (800) 666-0206 (1-703-684-2452 outside U.S. / Canada)
Citation: Standard Methods Online
 
Brief Method
Summary:
 Volatile organic compounds are transferred from the aqueous to the gaseous phase by bubbling an inert gas through a water sample contained in a purging chamber. The vapor is swept through a sorbent trap that adsorbs the analytes of interest. After purging is complete, the trap is heated and backflushed with the inert gas to desorb the compounds onto a GC column. The GC is temperature-programmed to separate the compounds.
Scope And
Application:
 Volatile organic compounds
Applicable
Conc Range:
 None given
Interferences: Impurities in the purge gas and organic compounds outgassing from the plumbing upstream of the trap account for most contamination problems. Avoid using non-TFE plastic tubing, non-TFE thread sealants, or flow controllers with rubber components in the purge and trap system. Ensure that the analytical area is not subject to contamination from laboratory solvents, particularly MtBE.
QC Requirements: Initial demonstration of capability, MDL, quality-control sample; laboratory reagent blank (LRB), laboratory-fortified blank (LFB), internal standard (IS), surrogate standard (SS), laboratory-fortified sample (LFS).
Sample Handling: Use 25- or 40-mL vial equipped with a screw cap with a hole in the center and TFE-faced silicone septum. Wash vials, caps, and septa with detergent, rinse with tap and distilled water, and dry at 105oC for 1 h before use in area free of organic vapors. Collect all samples in duplicate and prepare replicate field reagent blanks with each sample set. After sampling and preservation, invert several times to mix. Chill samples at 4oC immediately after collection and hold chilled in an atmosphere free of organic solvent vapors until analysis.
For samples and field blanks that do not contain residual chlorine, add HCl (4 drops 6N HCl/40 mL to prevent biodegradation and dehydrohalogenation. Note: HCl may contain traces of organic solvents. Verify freedom from contamination before using a specific lot. For samples and field blanks that contain residual chlorine, add ascorbic acid (25 mg/40 mL), but demonstrate that this reductant is appropriate for the specific sample matrix.
Max Holding Time:
 14 d after collection
 
Relative Cost: $201 to $400
URL to obtain ordering information for this method:
http://www.standardmethods.org/
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