I'm planning to determine phosphate concentrations in a solution via adding Iron(III) and weighing the precipitated ferric phosphate.
However, I read that ferric phosphate has a dihydrous form, which is slightly soluble. Furthermore, temperatures of over 200 degrees C are required to dehydrate this.
This is inconvenient for me, and I'm wondering if there is a way to correct for the presence of the dihydrate which means not all the phosphate will be precipitated, as well as the fact that the precipitate will be a mixture of the anhydrous and dihydrous forms. Another method to dehydrate it would work, or maybe a table of what proportions the anhydrous and dihydrous forms exist in under different conditions, so I can just factor it in.