Cortisol, serum or plasma

Equipment : Roche Cobas Pro e801

Method : The electrochemiluminescence immunoassay “ECLIA” is intended for use on cobas e immunoassay analyzers.

Competition principle. Total duration of assay: 18 minutes.
▪ 1st incubation: 6 µL of sample is incubated with a cortisol-specific biotinylated antibody and a ruthenium complex labeled cortisol derivative. Depending on the concentration of the analyte in the sample and the formation of the respective immune complex, the labeled antibody binding site is occupied in part with sample analyte and in part with ruthenylated hapten.
▪ 2nd incubation: After addition of streptavidin-coated microparticles, the complex becomes bound to the solid phase via interaction of biotin and streptavidin.

The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell II M. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier.
▪ Results are determined via a calibration curve which is instrumentspecifically generated by 2‑point calibration and a master curve provided via the cobas link.