Is it possible to determine the Ka of a weak acid at points other than the halfway point of a titration? Explain.

I don't think it is but I've not thought about it until 30 seconds ago. One CAN do the titration with a pH meter BUT we don't know the base concn or the acid concn. We using the half-way point to the equivalence point, we are using

pH = pKa + log (base)/(acid) and at the exactly half way point, we KNOW for certain that base = acid, the ratio is 1, log 1 = 0 and pH = pKa. If the base and acid can be measured some other way the pKa can be determined at some other point. On short notice I can't think of another way of doing it.