Fe 2+ and MnO4- titration? As a lab experiment, I am preparing a mixture of iron tablets dissolved in sulfuric acid so they can be titrated against $\ce{MnO4-}$. The tablet contain insoluble filler material.

Why is it important this 'filler' be removed when preparing the iron tablets solution?
Insoluble doesn't mean unreactive. The filler must be something which would be oxidized by permanganate in acidic solution.