Methods for the desalting of biological samples: a simple approach to

Abstract

The present invention provides new methods for desalting samples of ionic polymers or weak electrolytes, preferable ampholytes (e.g., peptides, proteins and glycoconjugates) or, compounds which can be transformed into these substances by complex formation. The methods of the present invention are based on the fact that salts can be removed from a sample by electrophoretically replacing the salts with ampholytes present in the ampholytic media of the anolyte and the catholyte or, with displacing cations and anions that have been introduced into the anolyte and catholyte, respectively, and which have mobilities less than the mobilities of the cations and anions to be removed from the sample. Although applicable to both small-volume and large-volume samples, the methods are particularly well suited for small-volume samples. Moreover, when applied to capillary electrophoresis, the methods described herein permit desalting of a sample in the same capillary tube as is used for the electrophoretic analysis. Alternatively, however, the sample can be withdrawn from the capillary tube following desalting and processed by techniques other than high-performance capillary electrophoresis (HPCE). Regardless of which method is used, the desalting methods of the present invention are rapid, highly reproducible, and they give a high recovery of sample compared to dialysis.