Electrical field-flow fractionation for metal nanoparticle characterization.

The potential of electrical field-flow fractionation (ElFFF) for characterization of metal nanoparticles was investigated in this study. Parameters affecting separation and retention such as applied DC voltage and flow rate were examined. Nanoparticles with different types of stabilizers, including citrate and tannic acid, were investigated. Changes to the applied voltage showed a significant influence on separation in ElFFF, and varying flow rate was used to improve plate heights in the experiments. For nanoparticles of a fixed size, the separation was based primarily on electrophoretic mobility. Particles with low electrophoretic mobility elute earlier. Therefore, citrate stabilized gold nanoparticles (-2.72 × 10(-4) cm(2) V(-1) s(-1)) eluted earlier than tannic acid stabilized gold nanoparticles (-4.54 × 10(-4) cm(2) V(-1) s(-1)) of the same size. In addition, ElFFF can be used for characterization of gold nanoparticles with different particle sizes including 10, 20, and 40 nm with a fixed stabilizing agent. For a specific separation condition, the separation of 10, 20, and 40 nm gold nanoparticles was clearly based on the particle size as opposed to the electrophoretic mobility, as the elution order was in order of decreasing mobility for 10 (-4.54 × 10(-4) cm(2) V(-1) s(-1)), 20 (-3.97 × 10(-4) cm(2) V(-1) s(-1)), and 40 (-3.76 × 10(-4) cm(2) V(-1) s(-1)) nm particles, respectively.