Homogeneous Potentiometric Enzyme Immunoassay for Human Immunoglobulin G

Human IgG Is determined In a homogeneous Immunoassay method which utilizes potentiometric CO₂ gas-sensing membrane electrodes. The method Is based on the Inhibition, by IgG, of CO₂ production from β-ketoadlplc acid catalyzed by chloroperoxidase (Cl-POD) enzyme conjugated to IgG antibody. Under appropriate experimental conditions, the Inhibition of the 1:1 enzyme-antibody conjugate Is shown to be a function of IgG levels In the μg mL^-1 range with good selectivity. Separation of bound from unbound conjugate or the use of a second antibody are not required In this method.