Purge and Trap - (P&T)

A sampling technique designed to extract volatile compounds from a matrix. The sample is placed in a sealed container and purged with a pure inert gas either Helium or Nitrogen. The purged analytes are transferred to an analytical trap. After the sample is purged, the trap is quickly heated and the retained analytes are transported to a gas chromatograph for separation and a detector for analysis. Some of the EPA methods requiring purge and trap:

EPA Method 5030 - PURGE-AND-TRAP FOR AQUEOUS SAMPLES
This method examines using purge and trap for the determination of Volatile Organic Compounds in water and water miscible liquid samples including soil and waste sample extracts from method 5035.

EPA Method 5035 - CLOSED-SYSTEM PURGE-AND-TRAP AND EXTRACTION FOR VOLATILE ORGANICS IN SOIL AND WASTE SAMPLES
This method examines using purge and trap for the determination of Volatile Organic Compounds in solid materials

EPA Method 8260 - VOLATILE ORGANIC COMPOUNDS BY GAS CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
Method to determine volatile organic compounds in waste samples. Applicable to all types of sample matrices.

EPA Method 524 - MEASUREMENT OF PURGEABLE ORGANIC COMPOUNDS IN WATER BY CAPILLARY COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY
Measurement of volatile organic compounds in drinking water by purge and trap sampling and GC/MS analysis.

EPA Method 624 - METHODS FOR ORGANIC CHEMICAL ANALYSIS OF MUNICIPAL AND INDUSTRIAL WASTEWATER
Measurement of volatile organic compounds in waste water by purge and trap

Gasoline Range Organics/Leaking Underground Storage Tank (LUST) analysis:
Purge and trap concentration of fuel product releases that can contaminate surrounding soil, groundwater or surface water.