Abacus junior 5
User’s Manual
23
4 OPERATING PRINCIPLES
4.1 Impedance Method
The volumetric impedance method (a.k.a. Coulter method) counts and sizes cells by
detecting and measuring changes in electrical impedance when a particle in a
conductive liquid passes through a small aperture.
Figure 7. Impedance method
Each cell passing through the aperture – where a constant DC current flows between
the external and internal electrodes – causes some change in the impedance of the
conductive blood cell suspension.
These changes are recorded as increases in the voltage between the electrodes.
The number of pulses is proportional to the number of particles. The intensity of each
pulse is proportional to the volume of that particle. The volume distribution diagrams
of the particles are WBC, RBC, and PLT histograms. EOS and BAS solutions
(treated with the respective reagent) and their separate histograms are analyzed.
Pulses are counted only in channels (in terms of femtoliter, fl), which are between the
lower and upper discriminators.
4.2 Principle of HGB Measurement
The lysed sample dilution can be measured by a cyanmethemoglobin method. The
reagent lyses the red blood cells, which release hemoglobin.
Hemoglobin iron is converted from the ferrous (Fe
2+
) to the ferric (Fe
3+
) state to form
methemoglobin, which combines with potassium cyanide (KCN) to produce the stable
cyanmethemoglobin, or hemoglobincyanide. Subsequently, the HGB concentration is
measured photometrically.
Note
:
The above-mentioned measuring method is used to determine the
HGB concentration. The HGB concentration can be measured
using cyan-free lysing reagents as well. In this case the effect is
the same but the used lyse is environmental-friendly reagent.
-
+
Blood cell suspension
External electrode
Internal electrode
Aperture
