Chemiluminescence immunoassay of aldosterone in serum

A chemiluminescence immunoassay (CLI) for the direct measurement of aldosterone in serum was developed with aminobutylethyl isoluminol (ABEI) as the label. In this competitive assay the samples are incubated with sample, antibody, aldosterone-carboxymethyl oxime-ABEI, and paramagnetic particles coated with second antibody. After magnetic separation and washing, the samples are incubated with 200 microL of NaOH (2 mol/L) at 60 degrees C for 30 min. In the luminometer the chemiluminescence is produced by the serial injection of 150 microL each of microperoxidase and H2O2 solutions. Comparison of results with an RIA method showed excellent agreement: CLI = 1.001 RIA + 0.020 (r = 0.99, n = 93). The method is simple and avoids the hazards and costs associated with isotopic waste. The label has a shelf life of at least two years.