EST Purge & Trap

Why choose purge & trap? How does it compare to other sampling techniques?

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With purge and trap analytes are purged using an inert gas from their matrix onto a thermal desorption trap which is then heated onto a GC.

With thermal desorption, you feed samples directly onto the trap and then desorb them into a second trap within your system, which is arranged much like the purge and trap.

Dynamic headspace, on the other hand, does not use a trap, as samples are heated in a closed vial and the volatilised gases are forced onto a GC.

In summary, purge and trap is best used for water matrices, thermal desorption best for air and dynamic headspace best for solids.

The Purge and Trap technique is more sensitive by at least a factor of 1000 over headspace techniques. Typical sensitivity is in the ppb range. By purging samples at higher temperatures, higher molecular weight compounds can be detected.