Flowing Dynamic Light Scattering with Potential to Improve Accuracy for Asymmetric Flow Field-Flow Fractionation

Asymmetric flow field-flow fractionation (AF4) separates constituents based on particle size and is emerging as a powerful tool for obtaining high-resolution information on the size of nanoparticles in liquid media. However, the size measurement inaccuracy has been reported for traditional dynamic light scattering (DLS) detectors when coupled to AF4 systems for the reason of additional component caused by uniform translation motions. In this paper, we developed a flowing DLS for AF4 study based on our sinc model reported previously. We further investigated the reliability of the size measurement provided by sinc model. The experiments were performed with suspensions of mono-dispersed polystyrene microspheres with a nominal diameter of 201 nm, 400 nm, 596 nm, and 799 nm at a range of different detector flow rates. The results obtained demonstrate that sinc model not only can measure the particle size but also flow velocity accurately. We believe our model can provide particle size information by coupling AF4 to DLS more accurately and pave the way for the complex AF4 system study, such as the electrical asymmetric flow field-flow fractionation in the flowing dispersion.