Colorimetric method for estimation of haemoglobin
Answers
The method to be described for the determination of hemoglobin
depends upon the comparison, in a calorimeter, of carbon monoxide
hemoglobin solutions, one of which has a known hemoglobin
content. Hoppe-Seyler (1) was the first to describe carbon
monoxide hemoglobin and to make use of this stable combination
for estimating the hemoglobin content of blood. He
devised a “double pipette” for comparing the unknown carbon
monoxide hemoglobin solution with the standard carbon monoxide
hemoglobin solution, prepared from hemoglobin crystals; but the
method never came into general use, because of the many technical
difficulties involved. Haldane (2) suggested a much simpler
method for comparing carbon monoxide solutions, using the apparatus
employed by Gowers (3) for comparing oxyhemoglobin
solutions with a picro-carmine standard. This apparatus was
later employed by Sahli (4) who prepared an acid hematin
standard by adding dilute hydrochloric acid to blood.
A critical discussion of the various methods in use for the
estimating of hemoglobin is beyond the scope of this paper. As
Haldane (2) has pointed out, artificially colored solutions and
tinted glass present great difficulties in standardization with a
definite strength of hemoglobin solution. With a certain strength
of color solution or tinted glass, it is possible to imitate quite
perfectly the tint of a given hemoglobin solution provided the
quality of light remains the same. Any variation from these
standard conditions, either in quality of light or strength of
hemoglobin in solution leads to serious errors.
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