Kovats index on HP-5ms

[Robert Zakrzewski]

I am going to estimate retention index on HP-5 ms UI column (30 x 0.25 x 0.25). The potential problem is I have only mixture hydrocarbons C10-C40. I am afraid that would be a problem with elution long-chained compounds. Does anybody has an expierience with it?

[Peter Apps]

Welcome to the forum.

I am not sure that I understand your problem - do you have components of your sample that have more than 40 carbon atoms, or do you anticipate problems eluting the heavier molecules in your alkane standard mixture ?

Peter

[Robert Zakrzewski]

Hello Peter,
I mean the second problem, I usually analyse flavours and worry that with my mixture (C10-C40) on that column I could observe heavy hydrocarbons for many injections in my following anayses.

[Peter Apps]

I see. A 40-carbon alkane will take a long time to elute. If you cannot source a standard without the heavier hydrocarbons than you may need to run your retention standard as the last run of the day and leave the column at high temperature overnight. It might also be a good idea to increase the inlet temperature, and the split ratio while the column is baking out.

Peter

[Robert Zakrzewski]

Thank you Peter,
I found application for HP-5ms for hydrocarbons up to C28, but I think I can try your suggestion for my mixture.
Regards
Robert