An electrochemiluminescence flow through-cell and its applications to sensitive immunoassay using N-(aminobutyl)-N-ethylisoluminol

An electrochemiluminescence (ECL) now-through cell with a carbon fiber elec trode for ECL detection was developed, and a flow injection analysis system containing the cell. was established. N-(aminobutyl)-N-ethylisoluminol (AB EI), an ECL reagent, was determined by this system. A straight-line calibra tion curve for ABEI (r = 0.999) was obtained from 6 fmol to 25 pmol, The de tection limit of ABEI was 6 fmol (S/N = 2) and the relative standard deviat ion was 1.7% at 1.5 pmol (n = 10). The system was used for immunoassay of h uman immunogloblin G (hIgG) with ABEI-labeled anti-hIgG. A calibration curv e of hIgG was obtained from 80 pg/mL to 1.3 ng/mL. The detection limit of h IgG was 80 pg/mL (S/N = 2), and the relative standard deviation was 1.8% at 0.5 ng/mL (n 10), Sensitivity and accuracy for sera samples were found to considerably exceed those of the conventional methods, such as single-radia l immunodiffusion and nepherometric immunoassay. The present system should prove useful for immunoassay.