Haematin inhibits the synthesis of porphyrin, and stimulates the synthesis of globin.
Phosphotungstic acid forms a lake with haematin.
Haematein must not be confused with haematin, which is a brown to black iron-containing pigment formed by decomposition of haemoglobin.
Interestingly the active component of haematoxylin is the oxidised form, haematin, although this rarely acknowledged in the literature which refer to haematoxylin staining.
During staining, alum haematoxylin-stained sections are usually passed on to a neutral or alkaline solution ( e . g ., hard tap water or 1 % ammonium hydroxide ) in order to neutralize the acid and form an insoluble blue aluminium haematin complex.