Separation and quantitation of silver nanoparticles using sedimentation field-flow fractionation

Sedimentation field-flow fractionation (SdFFF) provides a mass based separation, and, thus, a size based separation for particles of uniform density. In this study, SdFFF was employed for separation and determination of size distributions of silver nanoparticles of about 100 nm in diameter. The relative abundances of each population in binary mixtures of silver nanoparticles were determined by mathematically deconvoluting the SdFFF fractograms. Various experimental parameters, including the field strength (channel rotation rate), flow rate, and the carrier composition, were varied to find an optimum SdFFF condition for separation and analysis of silver nanoparticles. The field and/or flow programming were also tested to improve the resolution. The silver nanoparticles were not resolved well when pure water was used as the carrier, due to charge interactions among the particles and between the particles and the channel wall. Water with 0.1% FL-70 was chosen as the dispersing medium and also as the carrier for SdFFF analysis of silver nanoparticles.