[mde4592]

I was running a 1ppm Standard with known components of H₂, N₂, O₂, Ar, CO₂, CH₄, CO, C₂H₄, C₂H₆ in a Helium balance on a Valco Model 5000 Trace gas analyzer, using a 5' Mol Sieve 5A precolumn and a 10'Mol Sieve 5A analytical column. When i ran our 5ppm Standard with the same components I got an unknown peak between the N₂ and the CH₄ elutions. Through other runs i've been able to rule out C₃H₈, Iso-C₄H₁₀, or N-C₄H₁₀. It's definitely in the cylinder and not the carrier H₂ or a leak in the sample line or GC.

Any ideas of what it might be or where i could find answers?

Thanks

[mde4592]

a little more information.

Standard has been run on a GowMac Series II 580 with a Haysep column and DID decector with no elution of unknown peak.

has been run on a GowMac 816 Molsieve 5A with FID with no elution of unknown peak.

Has been run on a Valco 500 TGA with Molsieve 5A PDD with unknown elution

Has been run on a Varian CP-3800 with Molsieve 13X PDHID with unknown elution

[mde4592]

http://www.flickr.com/photos/de_haven_photography/8536116359

http://www.flickr.com/photos/de_haven_photography/8537219402

not sure how to post pictures, but the following links will take you to two of the runs. one of the 5ppm with the unknown elution. and the other of the 1ppm with out the elution.