In direct potentiometry, if I am only given the change in potential measured by an ion selective electrode. How do I calculate the corresponding change in concentration of that ion?

Thanks

Question

In direct potentiometry, if I am only given the change in potential measured by an ion selective electrode. How do I calculate the corresponding change in concentration of that ion? 

Thanks

aaronq · Answer

you would use the nernst equation, but a modified version. 

it would be like E = E* + (RT/nF)ln[ion]

where E* is a constant accounting for all the other potentials

anonymous · Answer

So the change is basically the ratio of concentrations that I get at the end?

aaronq · Answer

no the change is the difference, not the ratio

anonymous · Answer

ok thank you!!

aaronq · Answer

no problem