Beckman Coulter COULTER LH 750 System, Справочник

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PN 4277248DD
3-4
OPERATION PRINCIPLES
AUTOMATIC ASPIRATION MODE
11. After the last tube in the cassette is aspirated, the cassette continues along the rocker bed
and is deposited onto the unloading bay platform. The left platform lifts the cassette into
the exit bay, where up to 12 cassettes can be stacked.
Aspiration
At the sampling station, after the cap is pierced:
1. A pump draws a maximum of 300 µL (LH 700 Series only) or 550 µL (LH 700 Series
SlideMaker) of sample through the needle and through the Blood Sampling Valve (BSV).
2. The blood detectors monitor the passage of sample through the BSV and aspiration lines.
3. The needle is withdrawn and the sample tube is reseated in the cassette.
Delivery
CBC
After the sample is aspirated:
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The center section of the BSV rotates and segments the sample into two separate
volumes.
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Beginning a few seconds before the delivery of the dilutions to the appropriate baths, 5
psi of pressure is sent to the WBC bath. This pressure allows drainage of any residual
liquid in the WBC bath, thus preventing carryover.
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The pressure continues during delivery and forms bubbles that mix each cell suspension
before sensing begins.
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At the beginning of the delivery, any residual rinse in the Hgb cuvette drains into the
waste chamber and the waste chamber drains.
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Diluent from the diluent dispensers drives the separated volumes of sample from the BSV
to the baths.
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One volume of sample, 1.6 µL, is delivered with 10 mL of diluent to the RBC bath. This
dilution is used for RBC/Plt counting and MCV/Plt sizing.
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The other volume, 28 µL, is delivered with 6 mL of diluent to the WBC bath. This
dilution is used to count WBC and develop Hgb.
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During delivery to the WBC bath, 1 mL of lytic reagent is added to the dilution to lyse
the red cells and convert Hgb.
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At the same time the lytic reagent is dispensed, 5 mL of diluent from the backwash tank
is transferred into the Hgb cuvette for the Hgb blank reading.
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The final dilution in the WBC bath is 1 part whole blood in a total volume of 251 parts.
The final dilution in the RBC bath is 1 part whole blood in a total volume of 6250 parts.
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The vent section of the piercing needle is rinsed, then dried by high vacuum.
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The center section of the BSV returns to the aspirate position.
Differential (Diff)
During aspiration of the blood sample, blood is pulled through two shear valves before it
reaches the rear blood detector. These shear valves isolate the diff and retic sample segments
for processing.