I've been looking for a molecule, to be used as a inclusion marker in size exclusion chromatography experiment, that fulfills the following criteria:
(i) Water soluble
(ii) Low mw, preferably less than 200 Da so as to be included as much as possible in the gel
(iii) Neutral, so that its properties do no change as a function of buffer pH and concentration
(iv) Doesn't interact with B(OH)3 buffer pH 6-10, so 1,2 cis-diols are not permitted
(iv) There is a straightforward way to assay it from aqueous chromatography fractions in pure water or various concentrations and pHs of borate buffer. I'm using a large gravity flow column and currently I can't do online detection.
The amount of this compound I want to load with my sample depends on how sensitive assay I can find for it... Hopefully in low mg regime.
So the idea is to see whether this inclusion standard elutes at the same position (volume) in water and various borate buffers or does the borate change the gel properties.
I welcome all comments...