1-48 Rapidlab 1200 Operator’s Guide: System Overview and Intended Use
02087462 Rev. V
The loss of electrons in the oxidation of H
2
O
2
creates a current flow that is directly
proportional to the glucose concentration in the sample.
In the lactate sensor, lactic acid from the sample
interacts with the lactate oxidase on the
surface of the measuring electrode to form pyruvic acid and hydrogen peroxide:
22
)(
34322
)(
363
OHOHCOOHOHC
acidpyruvic
LOD
acidlactic
+++
→
where LOD is the lactate oxidase.
The polarizing voltage is sufficient to cause oxidation of the hydrogen peroxide to oxygen:
The loss of electrons in the oxidation of H
2
O
2
creates a current flow that is directly
proportional to the lactate concentration in the sample.
Hemoglobin and its Derivatives
Hemoglobin analysis yields important information necessary to assess the function of the
oxygen transport system. The need for hemoglobin determinations led to the development
of a number of methods to determine the concentration of total hemoglobin, hemoglobin
derivatives, and dyshemoglobins in human whole blood. The presence of dyshemoglobins
and toxins changes the oxygen binding capacity of hemoglobin and therefore its ability to
transport oxygen.
19
Hemoglobin is a tetrameric protein consisting of 2 pairs of polypeptide chains, each chain
having a heme group containing 1 atom of iron. Each molecule of hemoglobin can bind up
to 4 molecules of oxygen, 1 at each heme group. Hemoglobin has a key role in the
transport of oxygen from the lungs to the tissues and the transport of carbon dioxide from
the tissues to the lungs.
The ability of hemoglobin to bind and release oxygen depends on several factors: pH,
pCO
2
, pO
2
, 2, 3-diphosphoglycerate concentration, and temperature.
20
The presence of dyshemoglobins (hemoglobins not available for reversible binding with
oxygen), such as carboxyhemoglobin, methemoglobin, and sulfhemoglobin, may also
affect the normal oxygen transport mechanism.
21
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