298 VI. HEMOGLOBIN 



been developed by van Slyke and are fully described in the book of 

 Peters and van Slyke (2141) • 



The determinations of the oxygen capacity (e.g., by the method of van 

 Slyke and Neill (2531,2574) measure the sum of hemoglobin and oxyhemo- 

 globin. In order to measure hem/globin also, this must first be reduced to 

 hemoglobin. Most reducers, however, interfere with the subsequent oxygen 

 liberation by ferricyanide and only titanous tartrate has so far been shown 

 to be applicable (480). 



Determination of the carbon monoxide capacity without reduction give 

 the sum of hemoglobin, oxyhemoglobin and sulf hemoglobin (2572). In the 

 presence of dithionite (2573) hemiglobin, sulfhem?globin, and choleglobin are 

 also included (cf. Chapter X, Section 5.3.). 



9.3. Spectrophotometric, Photoelectric, 

 and Spectrocolorimetric Methods 



These methods are little less exact than manometric methods. It 

 is advisable, however, not to rely on the values of the extinction 

 coefficient given in the literature, but to measure these under standard 

 conditions with hemolyzed normal blood of a concentration known 

 by manometric oxygen capacity determination. These methods 

 require expensive apparatus, but the estimations are easy and rapid, 

 and hence suitable for clinical use by well-trained workers. The 

 particular advantage of spectrophotometry is its adaptability to a 

 variety of problems, such as measuring the concentrations of hemo- 

 globin, sulfhemoglobin, or carboxyhemoglobin in mixtures with oxy- 

 hemoglobin or even in more complex mixtures (cf. Section 9.6.). 

 Clear solutions must be obtained and the absorption of the stroma 

 is not entirely negligible, but even faint cloudiness can be detected 

 by carrying out control measurements in regions in which the absorp- 

 tion of hemoglobin derivatives is small. 



The direct spectrophotometric or photoelectric estimation of oxy- 

 hemoglobin in dilute hemolyzed blood is probably the best method 

 for future clinical use. Practically clear solutions are easily obtained 

 by the use of dilute ammonia (0.01 to 0.1%) or sodium carbonate 

 (0.01 to 0.1%) as dilution liquid. 0.4% ammonia as suggested by 

 some authors is less suitable (1878,2728). Phosphate buffer of pH 8 

 has been recommended' C56>^). In our institute the measurement is 

 carried out on a 1 : 100 dilution of blood in 0.01% sodium carbonate 

 and the extinction is read at 576 mn. This method has given results 

 comparable in exactness with the manometric method, and similar 



