1.2.1 QBC Centrifugal Hematology Tests
(continued)
Coated reagents in the QBC blood tube enhance the visual separation between cell layers and provide differential
staining so that tubes can be read by non-automatic and automatic QBC analyzers.
1.2.2 QBC Malaria Test
The centrifugal test for detecting malaria parasites is based on a high precision glass capillary tube containing
an equally precise plastic float. When the blood-filled tube is centrifuged at high speed for five minutes, the float
is buoyed by the packed red cells, automatically positioning the float within the buffy coat layer, between the
packed red cells and the plasma.
During centrifugation, blood cells in the buffy coat separate according to their densities, forming visibly discrete
bands (Figure 1-3). Platelets constitute the topmost layer, lymphocytes and monocytes the middle layer, and
granulocytes, being the heaviest of the buffy coat cells, concentrate immediately above the packed red cells.
Reagents coated in the QBC Malaria Test tube promote separation and metachromatic staining of these cells.
Examination of the centrifuged blood under a fluorescence microscope, or a light microscope with the QBC
ParaLens Advance
TM
LED fluorescence microscope attachment, readily permits the detection of malaria in
the infected cells and plasma. Direct malaria detection by the QBC Test method is therefore more rapid than
conventional blood-film microscopy.
1.3 PRINCIPLES OF THE PROCEDURES
1.3.1 QBC Centrifugal Hematology Tests
The QBC Capillary Centrifuge is designed to spin up to 20 QBC blood tubes at the force-time requirements
needed to produce optimally packed cell layers for cell counting and analyses. QBC blood tubes are 75 mm glass
tubes, internally coated with potassium oxalate, acridine orange, anticoagulants, and an agglutinating agent. The
tubes are sealed with a plastic closure or rubber stopper and contain a precision-molded float within the blood-
filled tube. Rotor speed and timing of the centrifuge are computer controlled for maximum consistency in the
formation of packed cell layers in spun QBC tubes.
GRANULOCYTE LAYER
LYMPHOCYTE/MONOCYTE LAYER
SECONDARY MALARIA
DETECTION ZONE
Blue Fill Lines
(55-65 µL)
White Label
Lines
PRIMARY MALARIA
DETECTION ZONE
LIGHT RED CELLS
(AROUND FLOAT)
DARK RED
CELLS
PLATELET LAYER
PLASMA
FLOAT
Figure 1-3. Differentiated Cell Layers
in Spun QBC Malaria Test.
2
Summary of Contents for QBC 425740
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