[Sebastian Falk]

Dear all!

We got reviewer comments on our SEC MALS data concerning the monodispersity of the sample.

When the polydispersity index Mw/Mn equals 1.000, then the sample is monodisperse.
We measure Mw/Mn between 1.000 for our best sample and 1.006 – 1.009 for our worst protein samples. Are there any thresholds in the literature one could refer to?

The experimentally determined mass fits the theoretical mass well, but we would like to make our arguments stronger by including the Mw/Mn ratio. I would appreciate any feedback.

Thank you! best
Sebastian

[Mario Lebendiker]

Dear Sebastian
Although we are doing many times SEC or IEX MALS, I never use “”polydispersity index Mw/Mn””, and never was asked for it…
I would consult the people of WYATT. They are very friendly and help us a lot .
In my case I use to consult Dan Somme for all my troubles.
If you do it, let us know his answer
Best,
Mario

[Sebastian Falk]

Thank you for all the suggestions.
I have been in contact with Wyatt and there is not clear cut criterium for Mw/Mn on this issue. While for polymers criteria have been defined, this is not really the case for the proteins.
I guess the best is to look the change of mass over the peak and judge the sample from there.

[Mario Lebendiker]

I would suggest to check your sample by analytical IEX or analytical HIC to check heterogenicity by charge or hydrophobicity. In case of hetero-dispersity you can applied MALS to the run to know the exact mass of each peak

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