GC-FID split peak issue

[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?

[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

[dblux_]

Split peaks ? Did you inject your samples manually ?

[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.

[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).