Chromatographic analysis method for methanol dimethyl ether
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What is the standard method for using FID to detect the levels of methanol and dimethyl ether? Each time, liquid methanol (considered to be of known concentration) and gaseous dimethyl ether are used as standard samples in this process, and the spectrogram is analyzed using area normalization. The reproducibility is poor. Are there any experts who have experience with this task? I would appreciate any guidance you can provide. Thank you!
Prepare a certain amount of methanol solution (with a very low concentration) to calibrate for methanol and dimethyl ether. There is a proportional relationship between the peak area of dimethyl ether and that of methanol, and this ratio needs to be determined by oneself
I believe the main reason for poor repeatability is problems with the sampling procedure: the amount of sample injected is usually very small, around 0.2 microliters. If the use of a microsyringe for sampling is not done properly, it can lead to errors. Similarly, improper handling of the injection process into the chromatograph can also cause errors. The combined effect of these two types of errors significantly impacts the accuracy of the results. Therefore, using a microsyringe for sampling is crucial, and so is proper injection into the chromatograph; by controlling these two aspects, the repeatability of the results can be improved.
I agree with the view from the 3rd floor. The poor repeatability mentioned by the original poster is generally not due to the instrument itself, but rather to the operation procedures; only after ensuring good repeatability in the operations can we assess the deviation of the instrument.
Oh, thank you, friend upstairs! ! I would like to ask again: will there be any difference in the peak formation patterns between using liquid methanol and gaseous dimethyl ether as standards, and using methanol vapor and dimethyl ether in online sampling? For TCD and FID as well, the conditions remain unchanged; although there are some adjustments in between, they all return to their original settings. Why is the peak emergence time later than under the previous conditions? ? Please help me out, experts! I’m just starting to work with chromatography and there are many things I don’t understand.: