I would like to add that contrary to popular belief, MPD would have to be treated as a volatile in the example you give below. It vaporizes, although very slowly, as can be proven by leaving a 1uL drop of it in open air for a couple of days.
Cheers, Jose Antonio Cuesta Seijo. "Jacob Keller" <j-kell...@md.northwestern.edu> wrote: > Dear Crystallographers, > > Is anybody aware of a calculator for vapor diffusion experiments to plot > concentrations of various solvent components as a function of time? For a > simple example, what happens when I mix a protein solution containing 50mM > NaCl 1:1 with a reservoir containing 50% MPD but no salt? Where is the vapor > diffusion equilibrium, and how does the drop composition change as a > function of time? More complicated would be experiments involving volatile > components other than water, as I think, for example, ethanol would almost > instantly equilibrate, then the water diffusion would kick in over a longer > time scale. Even more complicated would be pH-dependent volatilities such as > acetate. I don't think this would be impossible to figure out, but it would > be nice if there were a pre-existing tool/server to do such. > > Regards, > > Jacob Keller > > > ******************************************* > Jacob Pearson Keller > Northwestern University > Medical Scientist Training Program > Dallos Laboratory > F. Searle 1-240 > 2240 Campus Drive > Evanston IL 60208 > lab: 847.491.2438 > cel: 773.608.9185 > email: j-kell...@northwestern.edu > ******************************************* > -- *************************** Jose Antonio Cuesta-Seijo Biophysical Chemistry Group Department of Chemistry University of Copenhagen Tlf: +45-35320261 Universitetsparken 5 DK-2100 Copenhagen, Denmark ***************************
