Other immunoenzymatic techniques

A typical consequence of this relation 17.9 is the non-linearity of the experimental curve when the concentrations are plotted along the abscissa and at the ordinate the percent absorbance of the solution relative to the reference obtained with the blank (C=0). This reference is obtained with the blank (all of the antibody sites are, in this case, occupied by the conjugated enzyme). 

The final absorbance measurement can be replaced by fluorescence detection (this is a fluorescence ELISA test). In this case the conjugated enzyme chosen is an alkaline phosphatase which converts the specific substrate into a fluorescent compound. 

This assay is essentially the same as previously described, except that since the antibody is fixed to the magnetic particles, a magnetic field is applied after incubation and before rinsing in order to maintain the antibodies against the container walls. 

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