Beckman Coulter COULTER LH 750 System, Справочник

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PN 4277248DD
3-12
OPERATION PRINCIPLES
MEASUREMENT OF HEMOGLOBIN CONCENTRATION
3. The mode is between 3 and 15 fL.
4. The @PDW is < 20
5. The height of pulses in channels 0 and 1 is < 1.5 times the height of the mode channel.
The PLT is then calculated as the area under the fitted histogram.
Special conditions include, for example, the presence of microcytic red cells or red cell
fragments that might interfere with counting in the platelet channels. All special cases result
in no fitted curve (but there is high confidence in the platelet count unless the count is
flagged with R).
For samples that are not special cases, but that fail normal curve fitting criteria, the raw
histogram count is further examined for interference. This most frequently applies to platelet
counts < 20,000. The raw histogram count between the left and right low points is used to
determine the platelet count.
The initial count is then coincidence corrected, voted on, averaged.
The histograms are also voted on and averaged.
Incomplete and overrange conditions are noted.
The counts are adjusted for calibration and predilute factors.
MPV and @PDW are derived, and @Pct is calculated.
For flagging, all platelet data, plus data from the WBC and RBC histograms is further
examined. The PLT is R flagged when specific conditions indicate the confidence in the
count is low. These include the Research Use Suspect flags Low End Interference and High
End Interference. Additionally, statistics and histograms are examined for the possible
presence of Giant Platelets and Platelet Clumps.
It is possible to observe:
r
A smoothed platelet histogram without a flagged platelet count (no PLT R).
r
Giant Platelet and/or Platelet Clump Suspect message with or without a flagged platelet
count.
3.5 MEASUREMENT OF HEMOGLOBIN CONCENTRATION
After the WBC count, the lysed WBC dilution drains into the hemoglobin cuvette for Hgb
measurement.
A beam of white light from an incandescent lamp goes through the cuvette and then through
an optical filter that has a center transmission wavelength of 525 nm. Light passing through
the filter falls on a photocell. The photocurrent thus generated is proportional to the
transmittance of the contents of the cuvette at the chosen wavelength. It is sent to the COMM
INTFC card where it is digitized. The digital information is sent to the Analyzer computer,
then to the Workstation.
A significant refinement of the Beckman Coulter systems is the introduction of a reagent
blank into the cuvette during each operating cycle. After the percent transmittance is