What does the quality report say? Did you filter all your liquids to 0.02 microns or better?

You have much material above the top size range of the instrument and it’s probably settling. This is reflected in the z-average.

Until you get quality data there’s little point in speculating.

Mr. Alan F Rawle ,

The quality report says effectively there are large particles or sedimentation and presence of fluorescence in the sample. Moreover, I have not filtered the sample, I prepare the suspension and taking an aliquot and adding ultrapurified water for the measurement.

Thank you so much for your comments.

Ms. Kalthoum Riahi ,

The suspension solvent of nanoparticles is a mix of acetic acid and water with pH adjusted. Over, I take a minimal quantity of this and adding ultrapurified water.

Thanks for your comments, I will do more dilutions of my sample

Filtration is the key here.

Chitosan nanoparticles are generally prepared dissolving chitosan in acetic acid solution and then we add TPP etc. Purification is very important if you are preparing for bio applications. There are several methods like centrifugation, dialysis membrane etc. Then, allow the nanoparticles solution to pass through syringe filter for DLS measurement as Alan F Rawle suggested.

Mr. Agnishwar Girigoswami ,

I´m making the nanoparticles for adding of phytic acid. However, I have never purified the samples. I appreciate a lot of your comments, so I can obtain best measurements. Only a question more in some cases the sample is lyophylized before of the measurement, is it possible omit this phase?

thank you

Lyophilization to store the sample. It is not important for the zeta measurement. Purity and filtration are very important.