Capillary electrophoretic immunoassay for alpha-fetoprotein with chemiluminescence detection

A capillary electrophoretic immunoassay with chemiluminescence detection (CEIA–CL) using a non-competitive format for analyzing tumor marker alpha-fetoprotein (AFP) has been developed. In this method, antigen (Ag) AFP reacts with an excess amount of horseradish peroxidase (HRP)-labeled antibody (Ab*). The free Ab* and the bound Ab*–Ag complex produced in the solution are separated by CE in a separation capillary. Then they catalyze the reaction of enzyme substrate luminol and H2O2 in a reaction capillary following the separation capillary. Parameters affecting the CE separation and CL detection were investigated. Under the optimal conditions, the free Ab* and the Ab*–Ag complex were well separated within 4 min, the linear range and the detection limit (S/N = 3) for AFP were 5–500 ng/ml and 0.85 ng/ml (1.2 × 10−11 M), respectively. The proposed method has been applied satisfactorily in the analysis of human sera samples.