[tamim83]

Does anyone have any clue where I may find the heat of sublimation for dipeptides?  I have looked for a while (in the obvious places) now and have found nothing.  I am really starting to think there is no data, but I do not want to give up.  I need this for a research project.  Thanks guys

[lemonoman]

I am really starting to think there is no data

I think you're right.  I can't find any either.  Not on the NIST webbook, not in journals...nowhere

[AWK]

There is a little chance to sublime peptides, though in mass spectroscopy sometimes a molar peak can be obtained (formally by evaporation of a substance , then its ionization)

[tamim83]

I found some data in a journal article that was in Russian a while ago.  I suppose it is accurate.  We don't want to completely sublime the peptides, we want just enough vapor to get a mass spectrum.  I am working with a crossed beam mass spec.  It ionizes the sample using a metastable noble gas beam (we are using helium). Since we are working within a vacum, I think we only need the vapor pressure of the dipeptides to be around 10^-4 torr or so. 

Thanks for looking around guys.   

[AWK]

Ther are other techniques of ionization that allow even "vaporization" of peptides, eq field desorption

[tamim83]

True.  The technique we are using hasn't been tried before (I think), we are working with a professor from another school to see if this technique is even possible.  He hopes that this could be a way to sequence polypeptides someday.  Since our lab is one of the very few with a cross beam w/ metastable set up, we are seeing if this is a possibility.  I think the other professor uses electrospray to ionize his samples (he is an analytical chemist)