Chromatography Forum

Hi everybody,
we have analized an essential oil by GCMS and we have identified the components by library search and retention index comparison. Now we want to quantify the components by area normalization with a GC-FID.
We would like to have the retention time of the peaks as similar as possible to the GCMS analysis.
We're going to use the same column and the same temperature ramp but we are not sure about the flow.
1) Anybody here knows an easy mode to transfer the column flow from a GCMS method to a GC-FID keeping the retention time constant?
2) Anybody here knows some source of compilations of Kovats index for essential oil on polar column (WAX type) or apolar column (DB-5, RTX-5 etc..)?

Thanks in advance for the answer..

Have a good day!!

Davide

I do not think there is a simple conversion factor for Kovats on GC/MS and FID. The major Flavours/Fragrance business local to me has a 60K+ reference for Kovats GC and GC/MS run separately on two different columns. Hopefully however your order of elution should remain the same and the retention time shift from the vacuum should be small so it should be possible to identify all you peaks easily. If you run Agilent kit , you might be able to fiddle with their Retention time locking software that is designed to ensure the same retention time between different GCs (same columns). Principle is similar but would it accept traces from MS to compare with FID ?

Set the carrier gas average linear velocity (not flow rate) the same for GC/FID and GC/MS.