Dialab GmbH
Operator's Manual DIAcheck series Rev-4 Page 14
1.4.5 CLOTTING METHOD (PT, APTT,..)
FIGURE 4: DETERMINATION OF TURNING POINT IN CLOTTING METHOD
The final reaction in the coagulation cascade is the transformation of fibrinogen
into fibrin catalyzed by thrombin. Fibrin formation results in clouding (higher
turbidimetric level) in the sample, which is measured by the photometer and
stored as the extinction. The result in seconds is the time from the start of the
reaction to the time of half rate of change (halfpoint).
1.4.6 CHROMOGENIC METHOD (ANTITHROMBIN):
The change of optical signal is not caused by clot reaction, but by the release of
color particles (pNA) which causes a yellow color. The change of color is measured
at 405nm and expressed as “dE/60sec” and proportional to the concentration or
activity of analyte.
1.4.7 IMMUNTURBIDIMETRIC METHOD (D-DIMER):
The change of light is caused by Antigen – Antibody reactions, which scatter the
light. The antibodies are linked to latex particles to amplify the optical reaction. The
change of light is proportional to the concentration of antigen like D-Dimer and
expressed as dE/120sec
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