Abstract
A rapid spectrophotometric determination of methemoglobin was made using the blood saturated with carbon monoxide. The concentration of blood methemoglobin was caluculated from a ratio between the density of carboxyhemoglobin at maximum absorption and that of carboxyhemoglobin and acid methemoglobin at isobestic point. This method was compared with the other two methods, i.e. Zijlstra and Muller's (Z-M) and Hasegawa's method, in which methemoglobin was determined in two components system involved oxyhemoglobin and methemoglobin. Constants of calibration at 0 % and 100 % of methemoglobin were 1.77±0.03 and 0.46±0.02 in this method, whereas, constants of 1.22±0.03 and 0.59±0.04, 4.68±0.40 and 1.15±0.03 were obtained at 0 % and 100 % point by Z-M and Hasegawa's, method respectively. The mean concentration of methemoglobin determined in the identical blood specimens by this method, Z-M and Hasegawa's method were 0.28±0.43 %, 0.38±0.98 % and 0.97±0.85 % respectively. Coefficient of variation caluculated from constants of calibration or contents of methemoglobin, which were determined by this method, was smaller than those of other two methods and this method was proved to have high accuracy. Using this method the blood methemoglobin concentration of 124 specimens from the inhabitants of Hinohara village, Nishitamagun, Tokyo metropolitan area was measured and mean value of 0.4±0.6 % was obtained. This mean value was lower than that of 3.0±3.2 % obtained fromi the patients in the Hospital of Showa University.
