L(+) 25 °C :
meso 25 °C:
The natural form is L-(+)-tartaric acid or dextrotartaric acid. So is that the pKa to use? With the phosphate buffer I used a pKa close to the desired pH for the calculation, so if this applies then I should use pKa2 of 4.25 rather than pKa1 2.95?