This PSA enzyme linked immunosorbent assay (ELISA) applies a technique called a quantitative sandwich immunoassay. The microtiter plate provided in this kit has been pre-coated with a monoclonal antibody specific for PSA. Standards or samples are then added to the microtiter plate wells and PSA, if present, will bind to the antibody pre-coated on the wells. In order to quantify the amount of PSA present in the sample, a standardized preparation of horseradish peroxidase (HRP)-conjugated monoclonal antibody, specific for PSA are added to each well to “sandwich” the PSA immobilized on the plate. The microtiter plate then undergoes incubation, followed by thorough washing of the wells to remove all unbound components. Next, a TMB (3,3',5,5' tetramethyl-benzidine) substrate solution is added to each well. The enzyme (HRP) and substrate are allowed to react over a short incubation period. Only those wells that contain PSA and enzyme-conjugated antibody will exhibit a change in colour. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the colour change is measured spectrophotometrically at a wavelength of 450nm ± 2nm.

In order to measure the concentration of PSA in the sample, this Human PSA ELISA Kit includes a set of calibration standards (6 standards). The calibration standards are assayed at the same time as the samples allowing the operator to produce a standard curve of Optical Density (O.D.) versus PSA concentration (ng/mL). The concentration of PSA in the samples is then determined by comparing the O.D. of the samples to the standard curve.