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Peak integration. Total of 2 compounds?
Posted: Mon Jul 06, 2009 3:45 pm
by rambiochem
I have such peaks with GC-FID, once eluting like A and another time like B. But if I am sure that there are 2 compounds, can the quantities of these two compounds be reported together (as total) in proportion of area of the whole peak?
Posted: Mon Jul 06, 2009 7:23 pm
by tom jupille
That's not a chromatography question, it's a regulatory question. If knowing the *total* of the two compounds (not the amount of each) suffices for your purpose, and is permitted by your standard procedures, then the answer is "yes".
peak A and b
Posted: Mon Jul 13, 2009 9:02 pm
by Willy
Just a comment on this topic. You said if you are sure there is 2 peaks under A type. I have already encoutered one problem with a peak that was doing this. It was benzyl alcool and phenol in the same chromatogram. Randomly we got a single or doubled peak for benzyl alcool. Sometimes it is due to bad chromatographic conditions (check liner volume with solvent/pressure in system)......I'm just saying are you sure there is 2 peaks under A? If yes and you are not sure of the components it will be hard to quantify.
Re: peak A and b
Posted: Tue Jul 14, 2009 5:38 am
by rambiochem
Yes, I am sure there are 2 compounds. I have checked it with external standards also. What do you mean by "check liner volume with solvent/pressure in system"?
2 peaks
Posted: Tue Jul 14, 2009 10:29 pm
by Willy
Hello,
I mean if it was only one peak one problem would probably be bad chromatographic conditions. When im saying check liner/system pressure is they can give that type of chromatography if they arent set for the type of analysis you're doing although it's very rare to get that type of chromatography. On the system i was using (a perkin elmer from mid 90's) i had that problem but coudnt figure out at the end what it was.
For you're question if you can identify both peaks im sure there is a way to separate them and quantify them (would need more info on condition, column used....etc..). If not i dont know if you can consider quantitation with peak height instead of peak area.....
Finally, with all experience that i have, only time we can do an addition of peaks to quantify something is when we know one product gives more than one peak in the chromatogram. Otherwise method isnt considered good to quantify.
If you have any questions in regard to this topic post it. ill try to help you resolve your problem.