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Column select for permanent gases / CO2

Question asked by cecile.daniel on Aug 5, 2019
Latest reply on Aug 5, 2019 by noreuter

We have put in service a 'select permanent gases /CO2 plot GC column' from Agilent

Here is the description of this special column  "Select Permanent Gases/CO2 is a set of two parallel columns that combines CP-Molsieve 5Å for permanent gas analysis and CP-PoraBOND Q for CO2 analysis. Column dimensions meet the need for fast separation, lowest level analysis, and quantification of argon/oxygen. The Select Permanent Gases column separates permanent gases and CO2 in a single run, and columns are coupled, tested, and securely mounted on the EZ-GRIP column mounting system"

 

The detector is an FID, the GC is 6890, the software is Chemstation rev. B. Carrier gas is Ar.Oven is # 60°C.No ramp.

 

When we inject pure CO2 on this column we get 2 peaks. The second peak is clearly identified as peak from CP porabond. But I dont understand the first peak of CO2?? eluting from the Molsieve ? The area of both peak are in the same order of magnitude.

We have eliminated double injection possibility

By the way analysis of all other geses is correct : N2, O2, CH4, CO

Any suggestion from the community ?

 

Thanks

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