This IL1 beta enzyme linked immunosorbent assay (ELISA) applies a technique called a quantitative sandwich immunoassay. The microtiter plate has been pre-coated with an Anti-IL1 beta Antibody. Standards or samples are then added to the microtire plate wells and IL1 beta, if present, will bind to the antibody pre-coated on the wells. In order to quantify the amount of IL1 beta present in the sample, Anti-IL1 beta Antibody (HRP) is added to each well to "sandwich" the IL1 beta immobilised 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 IL1 beta will exhibit a change in colour. The enzyme-substrate reaction is terminated by the addition of a stop solution and the colour change is measured spectrophotometrically at a wavelength of 450nm ± 2nm.