following a study of the spectrophotometric properties of ortho-tolidine and its oxidation products , with particular attention to variation brought about by change in the hydrogen ion concentration , a method for the quantitative estimation of haemoglobin in serum and urine in which ortho-tolidine is substituted for benzidine in a peroxidase system is described .
C0030011
oxidation
C0027021
peroxidase