In my carrier gas line I use a moisture trap( indicating
Drierite-Molecular Sieve) and a Helium Purifier with these I then use
high purity helium. I don't have any traps on my reference gases.

I have another problem. I recently changed my combustion column on the
NA 1500, I have the Conflo II and a Delta-S. The delta-15N of my
reference Acetanilide was running -1.1 to -1.3 after the change it is
-1.4 to -1.8, I also have an integrator on the thermal conductivity
detector of the EA. The nitrogen response factor increased after the
column change meaning I am getting less N-area per unit weight N. I am
about to pack another combustion column but thought I would seek
opinions first.

Thanks,
Pat

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Patrick D. Anderson
Researcher
Great Lakes WATER Institute
Univ. of Wisconsin-Milwaukee
600 E. Greenfield Ave.
Milwaukee, WI 53204
Phone: 414-382-1731