ELECTROPHORETIC SEPARATIONS USING SWEEPING FIELDS

Sweeping-field electrophoresis is investigated as a method for increas ing the resolution of low-voltage slab gel separations. In this techni que a low direct current (DC) voltage is time multiplexed to an array of periodically spaced electrodes placed along the length of the slab in a manner that follows the band migration. Because the electrode spa cing is smaller than the slab length, a larger field is generated, yie lding an improved separation. The effect of the nonuniform electric fi eld on band distortion is studied in some detail. Experimental band di stortion results showed good agreement with theoretical predictions in a macroscopic sweeping-field electrophoresis system. Both analytical and numerical results show that band distortion can be effectively min imized when an appropriate sweep rate is selected for a narrow band ra nge. Using this scheme we have achieved the same number of theoretical plates as a DC-driven system with one third of the drive voltage.