MICRODETERMINATION OF OXYHEMOGLOBIN, METHEMOGLOBIN, AND SULFHEMOGLOBIN IN A SINGLE SAMPLE OF BLOOD

Abstract

Methemoglobin--When sodium cyanide is added to a solution of MHb (Fig. l), the characteristic absorption band at 635 mp is almost completely abolished by the conversion of MHb into cyanmethemoglobin (MHbCN). The resulting change in optical density is directly proportional to the concentration of MHb. This change in optical density may be measured on the photoelectric calorimeter (1) with a color filter which transmits a narrow spectral band in the vicinity of 635 mp (Fig. 1). Sulfhemoglobin-The depth of the 620 rnp absorption band of SHb (Fig. 2) is unchanged by the addition of cyanide, hence the concentration of SHb in a solution containing HbOt, MHb, and SHb is proportional to the residual optical density of the solution after the MHb has been converted into MHbCN by addition of cyanide. This measurement can be made on the photoelectric calorimeter with a suitable filter (Curve 620 of Fig. 2) on the same solution used for the MHb determination. A correction must of course be made for the small, though not negligible, absorption of HbOn and MHbCN at 620 m/l.