Tandem electric field gradient focusing system for isolation and concentration of target proteins

Two electric field gradient focusing (EFGF) systems, one based on a hollow dialysis fiber and the other based on a shaped ionically conductive polymer were serially integrated to trap and concentrate selected proteins while simultaneously desalting and removing other unwanted proteins from the sample. A series of experiments were performed to test the EFGF systems individually and after integration. Online concentration of amyloglucosidase indicated a concentration limit of detection of approximatedly 20 ng mL−1 (200 pM) from a sample volume of 100 μL. Concentration of human α1-acid glycoprotein with simultaneous removal of human serum albumin was also demonstrated. Elimination of small buffer components while concentrating trypsin inhibitor, and selective concentration and separation of myoglobin from a mixture were performed using the integrated EFGF system.