Gas chromatography issues
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The sample gas mainly consists of nitrogen, hydrogen, carbon monoxide, carbon dioxide, and methane; there is no oxygen present. However, when analyzed by gas chromatography, a very high peak appears at the position corresponding to oxygen, but it is certain that this is not oxygen. So what could it be? This post was last edited by zjs0536 on 2009-2-28 22:10.]
Could you please tell me the column model? Generally, a hydrogen peak is the more likely possibility. If possible, it is recommended to use normally diluted hydrogen gas and perform a single-spot analysis in order to confirm whether the retention times of the single-spot peak and the mixed-spot peak are the same; this makes qualitative analysis easier. For each column, the peak shape varies under different carrier gas conditions, and this issue can be resolved by comparing with standard spectra.
Stainless steel column, 5A molecular sieve, hydrogen as the carrier gas
Is it for synthetic ammonia? Is the CH4 factor taken into account? Are there standard reference charts? It should be the oxygen-nitrogen peak, where CO intersects with N2; the one closest to it is CO, followed by CH4. Are you referring to some other strange peak other than these? Helium and neon peaks are also possible. I hope to see a diagram, as that would make the analysis more intuitive. Otherwise, it feels a bit like getting ideas by eating candy. This post was last edited by chengjingbao on 2009-2-28 23:07.]
Check whether any other substances are formed (impurities or raw materials, etc.), adjust the operating conditions, and consider preprocessing the sample
Stainless steel column, 5A molecular sieve, hydrogen as the carrier gas; the peak at this oxygen position cannot be a hydrogen peak. Since hydrogen is used as the carrier gas, it is impossible for hydrogen to appear as a peak. It must be the oxygen-nitrogen peaks; however, when stainless steel columns are used with 5A molecular sieves and installed properly, these two peaks are somewhat separated from each other. In this case, the four stainless steel columns equipped with 5A molecular sieves all showed a certain degree of separation between those peaks. To determine the methane content, you can use the same column with nitrogen as the carrier gas; this way, methane can be measured. Generally, at a column pressure of 0.06 MPa, the peak appears in a little over two minutes. Methane cannot be detected when hydrogen is used as the carrier gas. Because in our production process we also need to analyze gas samples; hydrogen and methane are measured using nitrogen as the carrier gas in stainless-steel columns filled with 5A molecular sieves, while other components (well, I can’t say that here :P) are measured using hydrogen as the carrier gas in stainless-steel columns filled with 5A molecular sieves. The times of 0.8 and 0.95 refer to the times when oxygen and nitrogen peaks appear. I hope this information is useful to you. If it really doesn’t work, I can also install a pillar for you.
The people upstairs have gathered together, so the answer should be pretty complete. All of this is discussed under the assumption that separation is possible; in addition, you also need to consider the occasional peaks that occur under abnormal conditions. This requires several repeated injections for verification.
Thank you to the friends above. It’s related to synthetic ammonia; at first I thought it was an ammonia peak, but it was still present after removing ammonia. If it were an argon peak, then that peak should not be very large, but here it’s quite significant!
Find a bottle of argon and give it a try; that’ll make it clear.
Hehe, the problem is that I’m only studying * there right now; I can’t do it yet. I’ll take care of it after I finish studying *
It appeared several times; could it be a peak caused by organic gases? If so, what gas could it be?