THE USE OF A HOLLOW-FIBER MEMBRANE MODULE IN SAMPLE CONDITIONING PRIOR TO ELECTROPHORESIS

A new method to continuously change the buffer conditions in samples p rior to electrophoresis by counter-current dialysis has been developed using a hollow fiber membrane module (VariPerm M, bitop, Witten). It is demonstrated that the collected fractions of a column eluate after hydrophobic interaction chromatography cannot be analyzed by sodium do decyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) due to the high content of ammonium sulfate. In contrast, when the hollow fiber membrane module is used for on-line desalting of the eluate during chr omatography, it is possible to detect distinct bands on SDS-gels even after sample concentration by evaporation. Moreover, adding polyethyle neglycol 20000 to the counter-current dialysis buffer the hollow fiber membrane module is suitable for combined on-line sample desalting and sample concentration of living organisms during free flow electrophor esis (FFE): a culture of Nitrosomonas eutropha which could not signifi cantly be detected by FFE without conditioning was successfully analyz ed when concentrated and desalted on-line during sample application.