Dilution buffer - (May/01/2019 )

I am trying to do buffer exchange by simple dilution. I have 200ul of protein in Buffer A, 20mM and 50mM NaCl. I want to dilute it with buffer B which is 25mM and NaCl 40mM. I want the buffers to exchange but the salt concentration to be 40mM-50mM.How much buffer would I add to the 200uL of protein? Will making it upto 2ml be enough?

Because the salt concentrations are so similar  - 40 mM and 50 mM, mixing them at a 1:1 ratio will give you a final concentration of 45 mM NaCl. This would mean adding 200 ul of buffer B mix to the 200 ul of protein already dissolved in buffer A.