Molar absorbance of cyanmethemoglobin from blood of different animals

The molar absorbance of cyanmethemoglobin at 540 nm was measured in 35 species of mammals, birds, and reptiles. Values obtained were compared with those measured on human cyanmethemoglobin by the same procedure. There was no significant difference (P greater than or equal to 0.1) between the human and animal blood values observed in 29 samples. In six cases (4 mammals, 1 reptile, and 1 bird), the significant difference (P greater than or equal to 0.05) did not exceed 5% of the human value. The practice of applying the accepted absorbance of 1.10 x 10(4) M-1 cm-1 per mole of iron in human cyanmethemeglobin for the analysis of animal blood will not cause more than 5% uncertainty. Such results are satisfactory for use in clinical veterinary medicine except for those research projects concerned with animal hemoglobin function and structure.