[jaybee99]

I would like someone to help me figure out how to calculate the Ionic strength of McIlvaine's Buffer. Specifically, I have beeen trying to figure out how the Ionic strength values listed in Table 1 in the publication by Elving, Markovitz and Rosenthal, which appeared in Volume 28, page 1179 (1956) of the Journal "Analytical Chemistry". I am grateful for any assistance that anyone can provide as I cannot reproduce their ionic strength values by any means that i have been able to think of. Thanks in advance for your help.

[AWK]

This should be quite easy with computer programs.
With calculator it is rather iteratative process.
I would be started with isolated two buffer with the same certain pH neglecting activity coefficients.

[Borek]

To add to what AWK wrote, the result will depend on the buffer concentration and model used.