Particle density determination using resonant mass measurement method combined with asymmetrical flow field-flow fractionation method.

A novel characterization system using a combinational analysis of the resonant mass measurement (RMM) and asymmetrical flow field-flow fractionation (AF4) methods is developed as a hybrid analytical tool for the particle density of mixtures of different-sized materials. The function of the RMM method is to determine the particle mass by observing the shift in frequency proportional to the particle mass. However, to determine the density of particles using the RMM method, information on the size or size distribution is necessary. Because the size distribution of the particles could influence the accuracy of the determination of the density of the particles, this study addresses the weak point of the RMM method using the AF4 method. First, AF4 is used to fractionate the narrow-sized distributed particles as an effective sample preparation method before the RMM assessment. Moreover, the accurate size distribution determined by the AF4 method with multi-angle light scattering analysis supports the reliable density determination by the RMM method on the transformation from the mass distribution of the particles to the density distribution. Using our developed combinational analytical method of RMM and AF4 methods for mixed particle samples (different sizes and different materials), the densities of the respective particles are evaluated. This approach clearly resolved the problems of the RMM method using a combination analysis with the AF4 method for RMM assessment on the density of particles. The investigated analysis method can have an important role in developing new applications of colloidal nano- and micro-materials in industrial and biological research.