Hi everyone,
I have still doubts about the CO2 calibration. What I do is using a loop (V=0.250ml) in a six-way valve and doing some pulses of CO2.
I mean, first passing through the loop a certain concentration of CO2, then sweeping the loop with N2 to the Mass Spectrometer and obtaining an gaussian peak of CO2 (a.m.u.) and then assuming that this peak's area corresponding to x amount of CO2.
Anyhow after several cycles, I can obtain a calibration curve but this calibration curve doesn't serve to my experimental result (Catalytic Oxidation) for example when I do the C balance, I have the way too much C than I expected as theoretically.
I would appreciate if you could help me about this problem.
Hakan
I think you have to buy a calibration mixture from a gas company (PRAXAIR) and then inyect different amounts of the standard.
Sweeping with N2 is not an accurate way of doing the calibration (difusion problems).
The best solution is to use a GC/MS system with a Porapak column or PLOT column
You should be using a fixed volume for injection. Your chromatographic behavior will change if you do not.
CO2 is a relatively easy calibration. You need multi-point standards; you can either buy them in air or you can generate them (say from acid/Na2CO3, for example). You are essentially using your MS as a residual gas analyzer; it works pretty well in that mode.
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