Chromatograph failure
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My instrument has been having problems lately; there are always stray peaks when samples are injected. I’m using a FID detector. Yesterday I aged the column throughout the night, and today the performance during injections is inconsistent. I’m not sure what the cause is. I’ve cleaned and reinstalled the system, but the problem persists. Please help me out; it’s urgent!
There are many reasons for this; your description isn’t clear enough. Generally, it can be ruled out from the following aspects: 1. Check whether there is a problem with the gas supply, such as using a gas cylinder for gas replacement, or poor quality of the air intake or gas output from the gas generator ； 2. The column has failed or there are issues with its composition. 3. The injection system is contaminated. 4. The detector is contaminated and needs to be cleaned
The columns are more likely to have problems; they still don’t work after being used all night. Should we consider replacing them? ? Unstable carrier gas is one factor; as for contamination in the sampling system, it should result in stable spurious peaks, and detector contamination is also a possibility. .
The friends on the first floor have basically covered all the possibilities; you can just proceed with verification based on those. If it is direct injection, focus on checking the injection pad ； Just had it refilled; check the quality of the gas cylinder ； For samples with high concentrations, check the vaporizer, column, and detector ； Irregular, irregular peaks; check the carrier gas. There is a drop-off peak; check the fuel gas or the generator. Ask more, be more active!
Thank you all; I will eliminate them one by one using the methods you provided.
If the carrier gas – hydrogen, air (more commonly used with air compressors) – contains organic substances, spurious peaks will also appear
Many friends have mentioned this issue; my family also faces the same problem. Another aspect is that high oxygen content in hydrogen can also cause spurious peaks. Yesterday I aged the column all night; today the performance during sampling was inconsistent. yaoyao0729 posted on 2009-10-14 16:15 – Detector contamination and insufficient column aging are the most likely causes
If sample contamination and impure carrier gas are ruled out, then the detector should be cleaned or the liner in the vaporization chamber cleaned, as contamination in these areas can cause numerous spurious peaks and artifacts.
Clean the liner in the vaporization chamber or clean the detector; check the split flow, especially the gasket purging – contamination in these areas can cause numerous spurious peaks and artifacts. Try another gas cylinder; it’s simple, and only consider replacing the chromatography column as a last resort.
It might be that the aging time was insufficient; if the aging process is completed properly, the stray peaks should remain stable even then. It can’t be on sometimes and off other times. Unstable carrier gas is one factor; detector contamination is also a possibility. .