title: Donnan effect or protein interference in ionised calcium measurements?
abstract: The observation that the ionised calcium concentration is higher if measured in the original serum sample than in an ultrafiltrate is examined by means of a theoretical model. It is concluded that this difference is a predictable consequence of the Donnan equilibrium and is not a result of protein interference with the calcium-specific electrode.
mesh_terms: D001798:Blood Proteins / Q000032:analysis*; D002118:Calcium / Q000097:blood*; D055598:Chemical Phenomena; D002621:Chemistry; D002712:Chlorides / Q000097:blood; D006801:Humans; D007477:Ions; D008956:Models, Chemical; D011485:Protein Binding; D012964:Sodium / Q000097:blood; D014462:Ultrafiltration
chemical_list: D001798:Blood Proteins; D002712:Chlorides; D007477:Ions; D012964:Sodium; D002118:Calcium