I will be using dialysis tubing. Would greatly appreciate advice on a buffer that speeds up the time of the dialysis.
Dear Brooke,
The following publication covers the answer to your question:
Rapid Commun Mass Spectrom. 2008 Aug;22(15):2391-7. doi: 10.1002/rcm.3622.
A facile microdialysis interface for on-line desalting and identification of proteins by nano-electrospray ionization mass spectrometry.
Sun L1, Duan J, Tao D, Liang Z, Zhang W, Zhang L, Zhang Y.
Author information
Abstract
The adverse effect of salts, especially inorganic salts, on electrospray ionization mass spectrometry (ESI-MS) is one of the most serious obstacles that might limit its application. Among the numerous desalting approaches, the microdialysis technique is favorable for large molecules, such as proteins. In this work, employing a hollow fiber membrane of cellulose acetate (MWCO 3000 Da), a simple, facile and efficient microdialysis interface with the dead volume of less than 1 microL was constructed for the on-line desalting and identification of proteins dissolved in high salt concentration buffer by nano-ESI-MS. Furthermore, with counterflow added, the desalting procedure was accelerated, and could be finished within 1 min. This system was successfully applied to the analysis of myoglobin dissolved in either high concentration ammonium acetate or sodium chloride buffer. The experimental results showed that, by using such a microdialysis interface, the salt concentration, even as high as 1 M, could be decreased by at least 2 orders of magnitude, while sample loss was less than 10%, demonstrating the potential of such an interface in broadening the application of nano-ESI-MS in the analysis of large molecules.
To view the full paper, please see attached file.
Hoping this will be helpful,
Rafik
Use ammonium bicarbonate, ammonium acetate, or ammonium formate buffer because they are volatile and therefore are most compatible with MS. Dialysis can be sped up by using dialysis tubing with the maximal suitable molecular weight cutoff, but I don't think the buffer makes much difference. Make sure the dialysis bath is very well-stirred to keep the sample inside the tubing well-mixed.
For faster buffer exchange, use centrifugal ultrafiltration devices.
Thank you both for the very helpful answers!
I was curious to know if anyone has had experience with benzoylated dialysis tubing, and if the decreased pore size would effect the length of the dialysis procedure?
Many thanks,
Brooke
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