Haemoglobin test

II. Acid haematin method using a haemoglobinometer (Sahli�s method)

In the course of a study of the blood in the anemias of infancy, certain discrepancies were encountered in the acid hematin method of determination of hemoglobin described by Sahli.The study of the cause of these discrepancies has led to a modification of the method to produce accurate determinations comparable with those obtainable when a determination of hemoglobin by measuring its iron content, or by the carbon monoxide hemoglobin method, is made. These modifications consist in: first, the use of N/10 hydrochloric acid as the diluent of the acid hematin instead of water; and second, the employment of heat to bring the reaction of formation of the acid hematin to its endpoint of equilibrium more quickly than it occurs in the cold.

Since the introduction of the acid hematin method by Sahli, various criticisms of it have been made. From the mechanical side these have been well summed up

 instument

1.haenoglobinometter

2.hemoglobin matching box 

3.hemoglobin tube

4.glass rod

5.alcohol  pad

6.N/10 HCL

7.leancet

  

Procedure

1. The diluent is N/10 Hydrochloric acid (HCL). Add it from the dropping bottle provided to the graduated tube, up to mark 2.
2. Measure 0.2 ml (20 �l) of well-mixed blood, with the provided micropipette (Sahli�s pipette) and transfer it to the HCL in the tube.
3. With the pipette beneath the surface of the acid, gently blow the blood.
4. Rinse the pipette by sucking up and blowing out diluent 2-3 times.
5. Thoroughly mix blood and acid using a fine glass rod (HCL will react with the haemoglobin and convert it into acid-haematin, which has a brown color).
6. Wait up to 3 minutes after adding the blood to allow the color to develop sufficiently to achieve an accurate comparison.
7. Add distilled water gradually to the mixture and mix the solution with glass rode.
8. Place the tube in the haemoglobinometer and compare it with the standard.
9. Continue to add distilled water until the sample firstly appears to be detectably pallor than the standard.
10. Note the level of the liquid in the tube.
    
    
    
    
    
    

Disadvantages

 

1.    It is tedious and time consuming to perform, especially with large number of samples.

It is not accurate (its accuracy is of the order � 15 %).