The principle behind Turnbull Blue Stain involves the reaction of ferrous iron with potassium ferricyanide under acidic conditions to form an insoluble blue compound. This reaction can be summarized by the following chemical equation: Fe2+ + K3[Fe(CN)6] → KFe[Fe(CN)6] The resulting blue precipitate is Turnbull's Blue, which is highly visible under a microscope, facilitating the detection of ferrous iron deposits in the tissue sample.
