Can you provide more information?

How did the manufacture measure the size?

Are you using the same technique?

What material is it and the approximate size?

How much larger are your results compared to the manufacturer's?

John Francis Miller SIR

TiO2 particle,

25 nm,

DLS

25 nm is the primary particle size which cannot be obtained by sonication as the material consists of fused aggregates typically with mean size (for paint grade TiO2's) around 300 - 350 nm. You can see this primary size by electron microscopy. However, if you made by sol gel (for example) a colloidal suspension of 25 nm TiO2, then it would be completely clear, like water. I suspect your powder gives a milky suspension indicating aggregated particle sizes >> 100 nm. Take a look at Slide 31 in (open in IE only; nor enabled for mobile viewing):

Dispersion and nanotechnology http://tinyurl.com/hpywsge

Alan F Rawle Thanks sir.