Estriol, Free ELISA kit

The Free Estriol ELISA is a competitive immunoassay. Competition occurs between estriol present in calibrators, controls, specimen samples and an enzyme-labelled antigen (HRP conjugate) for a limited number of anti-estriol antibody binding sites on the microplate wells. After a washing step that removes unbound materials, the TMB substrate (enzyme substrate) is added which reacts with HRP to form a blue-coloured product that is inversely proportional to the amount of estriol. Following an incubation, the enzymatic reaction is terminated by the addition of the stopping solution, converting the colour from blue to yellow. The absorbance is measured on a microplate reader at 450 nm. A set of calibrators is used to plot a calibrator curve from which the amount of estriol in specimen samples and controls can be directly read. Serum and salivary assays follow the same procedure except that the volume of the calibrators, controls and samples dispensed into the microplate wells is 10 μL for serum assays and 20 μL for salivary assays.