Method using ortho-tolidine for the quantitative determination of haemoglobin in serum and urine

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. The method is designed to measure haemoglobin value within the range 0-125 mg. per 100 ml. Evidence is presented showing that it gives results equal in accuracy and reproducibility to a benzidine method in common use and for reasons stated is a more satisfactory technique for estimating the haemoglobin content of urine.