4.

Cumulative frequency curves of particle size distribution obtained from the COA-DMAS measurement of the polydisperse silica particle suspensions. Red (MEM and dialysis): Dialyzed silica particle suspension, Black (UPW): Silica particle suspension directly dispersed in ultrapure water, and blue rectangle: Reference value determined by scanning electron microscopy. Note that the lower size limit was set at 50 nm, and particles larger than 50 nm were included in the count. The vertical axis, labeled “Undersize percent” shows the percentage of particles with a size at or below a given size.