Enhanced chemiluminescent sandwich enzyme immunoassay for hen egg lysozyme

A sensitive chemiluminescent sandwich-type enzyme immunoassay for hen egg lysozyme was developed. The assay was performed on polystyrene microtitre plates using immobilized specific polyclonal rabbit antibody against lysozyme, a peroxidase conjugate and the H2O2/luminol-enhanced chemiluminescence detection reagent. The chemiluminescent signal was detected using either a microplate luminometer, or photographic film in a camera luminometer. The detection limit for lysozyme was 0.3 ng/mL, and this was three times lower than that obtained using a colorimetric method with H2O2 and o-phenylendiamine as substrates. Recovery of the assay was 97-112% and the relative standard deviation ranged from 3.6% to 10.3%. The immunoassay overcame interference from the food sample matrix when lysozyme, used as a bacteriostatic agent, was measured.