I'm wondering what, other than cellulose, might be contained in filter paper (the kind routinely used in Buchner filters / normal funnels).
A search here on Chemistry Stackexchange shows that at least one additive is used to modify the visual appearance of some filter paper (for improved "whiteness" / "fluorescence").
What additives may be contained in filter paper? What are their properties (solubility and potential chemical interference)? And how could one get rid of them prior to use, without consequence on the paper's filtering properties?
When used to filter away precipitated contaminants I usually rinse my filters in hot purified water before use (more with residual acid traces in mind). How would you guys prepare them for extreme minimal contamination?