Abbott CELL-DYN 3200 System Operator's Manual page 98

Principles of Operation
Sample Analysis Cycle Overview
Hemoglobin Analysis
WBC Analysis
3-4
1. The Diluent/Sheath Syringe injects 1.7 mL of diluent through the Shear
Valve where the 12 µL HGB volume is transferred to the HGB Flow Cell.
2. The HGB Lyse Syringe dispenses 0.9 mL of HGB Lyse into the line after the
diluent has transferred the HGB volume to the HGB Flow Cell. The entry
point for the HGB Lyse is between the Shear Valve and the HGB Flow Cell.
3. The segment, lyse, and diluent are routed to the HGB Flow Cell where the
dilution is swirl mixed. The final dilution is 1:218.
4. A low-energy LED attached to the HGB Flow Cell measures the absorbance
of light at 555 nm. The absorbance is proportional to the HGB concentration
of the sample.
WBCs are analyzed optically as follows:
1. The WBC Lyse Syringe dispenses 0.973 mL of WBC Lyse reagent through
the shear valve where the 20 µL WBC volume is transferred to the WBC
Mixing Chamber.
2. The segment and reagent are then routed to the WBC Mixing Chamber where
the dilution is swirl mixed. The final dilution is 1:50. The diluted sample
remains in the mixing chamber for 14 seconds for the lysing of the red blood
cells.
3. The Sample Transfer Pump transfers the WBC dilution from the WBC
Mixing Chamber to the Optical Flow Cell Sample Feed Nozzle.
4. Diluent/Sheath reagent, under constant pressure in the Sheath Reservoir, is
directed into the Optical Flow Cell.
5. Sequentially, the Sample Metering Syringe injects 46.5 µL of the WBC
dilution into the flow cell at a pressure (and speed) lower than that of the
diluent/sheath reagent.
6. The higher speed of the sheath, which surrounds the WBC dilution, and the
special geometry of the flow cell combine to focus the WBC dilution stream
so that individual cells can be counted.
7. A laser beam is focused on the flow cell. As the sample stream intersects the
laser beam, the light scattered by the cells is measured at four different
detectors located in the forward (0° and 10°) and side (90° and 90°D) angles.
CELL-DYN ® 3200 System Operator's Manual
9140181H—October 2001
Section 3