Siemens ADVIA 2120, Operator'S Manual, Page: 290 / 477

Methods 8-21
Hemoglobin Method
Chemical Reactions
The ADVIA 22120/2120i/22120/2120ii Hematology system normally uses a
cyanide-free hemoglobin method, but can be configured to use a reagent that
contains cyanide.
The sample and the ADVIA 2120/2120i CN-FREE HGB reagent or ADVIA
2120/2120i HGB reagent are mixed in the hemoglobin reaction chamber
(colorimeter). The hemoglobin chemical reactions consist of two steps:
ADVIA CN-FREE HGB Reagent
Step 1
Red blood cells are lysed to release hemoglobin
Step 2
The heme iron in the hemoglobin is oxidized from the ferrous to the
ferric state and coordinates one hydroxide ion and one water molecule as an axial
ligand to form monoaquomonohydroxyferri-porphyrin as the reaction product.
ADVIA HGB Reagent
Step 1
Red blood cells are lysed to release hemoglobin.
Step 2
The heme iron in the hemoglobin is oxidized from the ferrous to the
ferric state, and is then combined with cyanide in the ADVIA 2120/2120i HGB
reagent to form the reaction product.
ADVIA 2120/2120i HGB
NOTE:
For more detailed information on the contents of ADVIA 2120/2120i
HGB reagent, please see Chapter 8.
ADVIA 2120/2120i HGB reagent contains a surfactant and potassium cyanide,
which are dissolved in an alkaline borate solution at pH 11.3.
The surfactant hemolyzes the red blood cells and then emulsifies the cellular
debris and lipids in a reaction mixture that is essentially free of turbidity.
After release of hemoglobin by hemolysis, the combined action of an alkaline pH
and the surfactant causes a rapid denaturation of the protein with solubilization of
the hemes by surfactant micelles.
The hemes then undergo air oxidation of ferrous iron to the ferric state and
combine with cyanide forming micellized ferriheme. Published studies show that
each ferriheme combines with two cyanide ions.
The mechanism and clinical performance of the Siemens Hemoglobin method
have been described. The presence of carboxyhemoglobin (even up to 100%) has
no effect on the reaction rate or transformation to the cyanated product.