Beschreibung:
<jats:title>Abstract</jats:title><jats:p>A new method to continuously change the buffer conditions in samples prior 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 dodecyl sulfate‐polyac‐rylamide 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 chromatography, it is possible to detect distinct bands on SDS‐gels even after sample concentration by evaporation. Moreover, adding polyethyleneglycol 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 electrophoresis (FFE): a culture of <jats:italic>Nitrosomonas eutropha</jats:italic> which could not significantly be detected by FFE without conditioning was successfully analyzed when concentrated and desalted on‐line during sample application.</jats:p>