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(4) Prozone Check
In immunological reaction, the absorbance of calibration curve falls at high concentrations
so that correct data is unobtainable (this is called "zone phenomenon or prozone effect").
Therefore, prozone check is performed by the two methods below and a data comment is
indicated when required.
< Antigen Readdition Method >
In 1-point assay, a small amount (approx. 50 µL) of sample containing antigen is readded
for the second reagent (R2 to R4) to check the change in absorbance before and after
addition (the dashed line in Fig. 2-3 indicates that absorbance falls due to excessive
antigen).
< Reaction Rate Ratio Method >
In 2-point assay, check is performed according to the ratio of the initial reaction rate after
addition of antiserum to the mean reaction rate.
Check Abs.
R1
(antiserum)
Rn (antigen)
Fig. 2-4 Reaction Rate Ratio Method
Fig. 2-3 Antigen Readdition Method
R1
(1st reagent)
Rn (nth reagent) Time
Time
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