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A Fast Autosampler Injection Can Promote DDT Degradation

12 Sep 2011

I’m continuing my series on Endrin and DDT degradation as part of EPA Method 8081 organochlorine pesticides analysis where I saw in a GC-ECD experiment that the ultra fast injection from the Agilent 7683 autosampler can enhance DDT degradation when using a single taper liner with NO WOOL.  That’s because the liquid sample is thrown directly to the bottom of the Agilent 6890 GC inlet where some of it contacts the hot metal inlet seal, somewhat surprisingly, given the narrow taper at the bottom of the liner.  Endrin degradation was not impacted, as much, if at all. 

A slower injection (“slow plunger enable” on my software) , which is still pretty darned fast with the 7683 autosampler, results in less DDT degradation, possibly by creating a “thermospray” (vaporized) injection and keeping most of the injected material above the hot metal seal at the bottom.

Is this a good reason to use wool in this application?