Circuit modification in electrical field flow fractionation systems generating higher resolution separation of nanoparticles

Compared to other sub-techniques of field flow fractionation (FFF), cyclical electrical field flow fractionation (CyE1FFF) is a relatively new method with many opportunities remaining for improvement. One of the most important limitations of this method is the separation of particles smaller than 100 nm. For such small particles, the diffusion rate becomes very high, resulting in severe reductions in the CyEIFFF separation efficiency. To address this limitation, we modified the electrical circuitry of the EIFFF system. In all earlier EIFFF reports, electrical power sources have been directly connected to the E1FFF channel electrodes, and no alteration has been made in the electrical circuitry of the system. In this work, by using discrete electrical components, such as resistors and diodes, we improved the effective electric field in the system to allow high resolution separations. By modifying the electrical circuitry of the EIFFF system, high resolution separations of 15 and 40 nm gold nanoparticles were achieved. The effects of applying different frequencies, amplitudes and voltage shapes have been investigated and analyzed through experiments. (C)2014 Elsevier B.V. All rights reserved.