What does the quality report say? Your PDI is 1 so you have very large material present and probably significant sedimentation. That’s why the z-average is much larger than your 2 peaks. To what size did you filter your continuous phase?

Thank you Dr Rawle for your answer. Unfortunately i did not the analysis myself and a operator did it and i dont access to quality report.after 10 days my sol is stable and there is no any sediment at all. I didn't filter the sol.

Your sample is contaminated with a huge amount of dust/dirt. All solutions used must be filtered better than you wish to measure. In your case, a 0.02 micron filter seems necessary.

But why the graph didn't show that?

Hi Mahdi,

The result for Z Average and the distribution are independent and calculated using different techniques.

Z Average comes from a method called Cumulants analysis, and involves a fit to the correlation function.

The distribution comes from an inversion analysis method where the analysis calculates what ratios of particles of a set size range would give a result that best matches the measured correlation function.

Any DLS result is only reliable if a reliable fit to the correlation function is obtained, and that requires the correlation function to not be perturbed by effects from dust, sedimentation, non-Brownian motion etc.

It looks like from your data that something large was present during the measurement that resulted in the high Z Average, but was larger than the size range used in the analysis for the distribution plot.

Hi Alexander and thank you for your answer. according to your answer, are all my results unreliable or just z average? can quality report help me? If there is something large in my sol why there isn't any sediment?

Your distribution is shown according to the intensity of the scattered light signal. One very large particle (

Thank you very much Dr Miller.

Thanks Sir Alan F Rawle it helps a lot.