I analyse Toluene with GC-FID (Elite 624 columns are specially engineered low to mid polarity columns (6%-cyanopropylphenyl)- 94% dimethylpolysiloxane)
There're some impurities in the sample with retention time 9.215, 9.480, 9.574, and 10.166
Toluene's retention time is at 8.984
I understand that the RT for a compound is not fixed as many factors can influence it even if the same GC and column are used.
But is there any way to identify the impurities ?
This is in my opinion impossible.
What you could do: are these peaks also present in your solvent? What is about the purity of your Standard? Or just in your Sample? If you have localized the source, you could send it to a mass spec facility to identify it, buy the corresponding chemicals and proove retention in your System.
Hi Catherine,
is your system only coupled with a FID or do you have an additional MS detector?
Without a MS an identification of the impurities isn't possible.
With the FID retention times you can estimate the polarity or the number of C-atoms (keyword: Kovats-Index).
https://www.researchgate.net/post/How_can_I_calculate_retention_index_Kovalts_index_by_GC-MS_for_essential_oils_analysis
Regards
Markus
No, using only GC-FID system can't let you know the type of impurities until you are not using any internal or external standards. For unknown constituent the prefered way is by using secondary characterization like MS under the similar conditions as mentioned by Christ.
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