Ibrahim Alsabih Yes, in manual mode. Your local representatives in Malvern Panalytical, Great Malvern, UK can help you here. Please indicate what analysis you wish to conduct on the data and we can help you too.

Exactly what Prof. Alan F Rawle has said. If you go to manual mode there the parameters can be set as per your choice.

Thanks for your answer. I have done these experiments already, the issue I'm having relates to Arginine clustering which has a faster decay on the correlation function compared with protein so my problem is with much smaller particles around 0.4nm.

We have already spoken to Great Malvern, UK.

They couldn't help.

Hi Ibrahim Alsabih

In the Zetasizer Nano software it is possible to change a range of settings that are used in the analysis to produce the particle size distribution, including thresholds and minimum and maximum size to fit and display.

These options can be found by clicking on the "Configure" box next to the "Analysis model" box, when either setting up the measurement SOP or when editing an existing result.

This could achieve what I think you are after, but changing any settings in the analysis can be fraught with risk of over resolving the data and leading to other spurious results.

Changing the display range would be a potential option if you want to "hide" the smaller particles, but if you want to change the analysis, I would be reluctant to advise of any settings without properly understanding your requirement for changing this data.

Ibrahim Alsabih Alex has provided you with the de facto answer to which I will add only minor comments. You're really pushing the limits of DLS at < 0.4 nm and your plot looks as good as you could possibly get from a clean system. Indeed many people will tell you that DLS is not applicable in this region. Given, too, that the diameter of a hydrogen atom is 0.074 nm approximately, then you're not talking of a large entity. I suspect that if the Malvern people can't help you in the UK, then there's little more that can be done. Sorry.

Hello,

I agree with Alan. By the way how is the shape of the autocorrelation curve?

Are you working with proteins?

Best,

Sébastien

Hi Ibrahim Alsabih , just wanted to point you to a few resources in addition to those already mentioned above:

• https://www.materials-talks.com/blog/2016/06/15/solvent-peaks-how-to-get-rid-of-the-buffersaltadditive-dls-contribution/
• https://www.materials-talks.com/blog/2015/07/30/arginine-for-stabilization/
• https://www.materials-talks.com/blog/2015/10/28/new-macro-to-export-dls-data-to-sedfit/
• https://www.materials-talks.com/blog/2015/08/19/advanced-research-software-features-for-the-zetasizer-nano/

Typically, most researchers want to avoid the "buffer peak", it does show with arginine. If you really want to dive in, you can export raw data, or use some advanced research features at your own risk.