Determination of Oxyhemoglobin by Means of the Duboscq Colorimeter.

Abstract

In the determination of oxyhemoglobin by the Dare method the glass standard is never of the same color as oxyhemoglobin and therefore a color match is impossible. A better color match has been obtained by determining acid hematin as in the Sahli and Newcomer methods. The color match is not perfect, however, and an hour wait is required for all of the hemoglobin to be changed to acid hematin. If monochromatic light is used the difficulty of matching colors is eliminated but for practical reasons the wavelength should be one in which the blood pigment shows considerable absorption. The Wratten color filter 74, epsilon, shows a high transmission at 540 mμ and the center of one of the absorption bands of oxyhemoglobin is at 541.7 mμ. Furthermore, the transmission of this Wratten filter is in so narrow a band as to appear monochromatic to the eye. Hence the Newcomer glass standard may be used for determining oxyhemoglobin if this Wratten filter is placed in the eyepiece of the colorimeter. A slight change in the spectrum of the Newcomer glass as has been made by Bausch and Lomb, does not prevent a color match being made. Diluting the blood 1-502 with distilled water resulted in complete laking in 15 minutes so that only this amount of time was required before making the reading. After a number of hours the formation of methemoglobin changed the reading, so it is necessary to take the reading between 15 minutes and 3 hours after diluting the blood.

If blood is to be collected during the night and the colorimeter readings made next day, the Newcomer method is preferable, but if the readings are to be made immediately (as during a physiological experiment) the present method is preferable.