How to calculate concentration of a protein based on known concentration and mw of other protein

I have a Peptide A (mw = 5074Da), the table below showed
measured concentration by [Qubit](https://www.thermofisher.com/order/catalog/product/Q33211) from 5uM up to 80uM solution.
All under 20uL solution.


[![enter image description here](https://i.stack.imgur.com/8u5nGm.png)](https://i.stack.imgur.com/8u5nGm.png)


Below is the standard plot for Peptide A (not sure if it's relevant or not):


[![enter image description here](https://i.stack.imgur.com/Z5uKTm.png)](https://i.stack.imgur.com/Z5uKTm.png)


Let's say I have another Peptide B (mw = 3102Da),
how can we calculate the *expected* [Qubit](https://www.thermofisher.com/order/catalog/product/Q33211) read of Peptide B based on Peptide A (just by calculation)?


For example just for 1 node: 20uM.




If knowing the concentration of peptide B is important and you have pure peptide B available, you should measure standards of known concentrations of peptide B in the assay.


The assay works through a dye that has little fluorescence in solution and a lot when bound to proteins. The mechanism of binding is not known or not divulged. While there is a claim that there is little variation of mass of protein sample vs. fluorescence signal, the data presented by the company uses larger globular proteins.


We don't know what the amino acid composition or the structure of your peptides are. We also don't know whether the assay works under native or denaturing conditions (the assay buffer has a pH between 6 and 8, but there is no information about its composition).


If knowing the concentration of peptide B is not so important, you could assume that the same mass of peptide will have the same fluorescent signal. Or you could use the assay to get a relative concentration if the absolute concentration is unimportant.


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