Anyone has experienced lose of recovery from volatile analytes that are traped by non volatile compunds in sample matrix?
I am using a method for fat soluble vitamins in oils but seens that my sample are traped in the injector,I am sure that I have vitamin but I can see nothing in some samples.
loong chain triglicerides are non volatile in 300ēC (my injector temperature)
any idea?

Have you tried extacting the vitamins out of the sample matrix first?

yes,but the triglycerides are very soluble in everything that the vitamin is:CHCl,Hexane,Acetone...

Then you should try SPE to trap the triglycerides. I don't know what phase you would use but there may already be a method developed. Have you tried calling the chemistry/applications group at Waters (800-252-4752) or another chromatography company.

We had this problem in the fatty acid analysis in plasma/serum. The coextracted lipids (TG, PL, ...) accumulated in the injector giving rise to slowly increasing discrimination (the higher FA started to decrease in concentration), J Chrom, 228, 75 (1982).
If your SPE, or whatever, doesn,t work 100% (how could it??) you can expect something of this sort. Many people do not see this, simply because they don´t do large enough series. Devising a cold injector which can be washed between each run (automatically) stopped this problem. It is hard to understand that the industry is not adopting this.

thanks everybody,
but what I think more strange is that some samples I have 2,3 or maybe 5% of vitamin and in the gas chromatogaph I see nothing,but in HPLC I see the peaks well,I already read about trap some analytes in injector but only when you have low concentrations,What I mean is :there is no doubt that my analytes are traped by noin volatile compunds ,there is?

If you can readily see the analytes of interest by LC why do you need to use GC?

in the GC I have a autosample and in the LC no.

Is the method validated for GC? Sometimes you have to bite the bullet and spend money when you can't get a method to work. Have you looked into buying a demo or used autosampler for your LC? What kind of lab do you work in?

other people in my lab(goverment lab for foods analysis)already quantitated Vitamins by GC but not in this matrix.
GC separations are more fast, I prefer put rotine analysis in a GC than in a LC.