I recently conducted an EDTA titration of milk to find its Calcium contents. I got a value significantly smaller than the theoretical value. (≈10 times smaller). I made $50ml$ samples to which I added $2ml$ 8M NaOH to precipitate any Magnesium ions. However, assuming milk is neutral, this would make the pH of the sample equal to $13.5$. Would this cause precipitation of Calcium? If so, how could I calculate the extent of this? I know it has to do with solubility, but it is not a part of the curriculum at my school, and after a long research, I am still lost. I would really appreciate the help.