[arjunsengupta]

what will be the effect of pH upon complexometric titration? probably it will have an effect upon the metal ion-indicator complex.moreover it may have an effect on the end point color change...is there any other aspect?

[Borek]

Most ligands can get protonated, and in most cases only non-protonated form is active, so the complxation equilibrium depends on the pH. That's the most important part.

Think, what pH is used for EDTA titration and why?