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GC-FID split peak issue
Posted: Tue Sep 12, 2017 2:57 pm
by swetha.rajagopal
This is my first time using a GC-FID and i am trying to understand the difference between a good and bad peak. I ran an unknown sample on a DB-5 column at a program ramp condition set at 50c for 1 min, followed by 20c/min to 200c and hold for 2 minutes. I obtained peaks that were split and had retention times that were not similar to the ones I obtained for my reference samples (the unknown consists of any or a mixture of the 10 reference samples). How can I troubleshoot this problem?
Re: GC-FID split peak issue
Posted: Tue Sep 12, 2017 5:49 pm
by GOM
Hi
Welcome to the forum
How can I troubleshoot this problem?
By giving more detailed information of your sample, reference, conditions and example chromatograms
The more you tell us the more we can help
Re: GC-FID split peak issue
Posted: Tue Sep 12, 2017 7:21 pm
by dblux_
Split peaks ? Did you inject your samples manually ?
Re: GC-FID split peak issue
Posted: Wed Sep 13, 2017 12:00 pm
by Bigbear
Are they truly slit, or two unresolved compounds? The only to find out with 2 dimension chromatography is to inject single component standards to check the RT's.
Re: GC-FID split peak issue
Posted: Wed Sep 20, 2017 7:03 pm
by swetha.rajagopal
My sample is an unknown that may consist of any of 10 references (ranging from polar to non-polar). I have already run the references separately and have obtained retention times for them in a nonpolar column at an isothermal temp of 60c. Those peaks were not split. It was a manual injection. The retention times were well resolved for all the references even when I ran them all on the same column but with a temperature programmed ramp and the peaks were not split either. But, when I ran my unknown on the same column (both isothermal and temp ramp), i got split peaks. How would i know if it is an injection technique problem versus something else? ( I did repeat the injection the same day and had the same problem).