[The determination of cortisol in plasma with a direct luminescence enzyme immunoassay]

The assay is based on the luminescent measurement of horseradish peroxidase. The IgG fraction of a cortisol antiserum is coated on suitable polystyrene tubes (in use for the measurement of luminescence). The enzyme activity of bound label was determined using a p-iodophenol enhanced chemiluminescent reaction. The assay was sensitive and precise for a wide cortisol concentration range and showed a good agreement with conventional ELISA-technique. There was no extraction necessary for cortisol from plasma. The diluted sample was heated to 60 degrees C or 8-aniline-1-naphthalene sulfonic acid was added in order to release cortisol from protein binding in plasma.