An evaluation of the detection limits possible for competitive capillary electrophoretic immunoassays

Using a high-affinity antibody for estradiol, thermodynamic and experimental limitations on detection limits for competitive capillary electrophoretic immunoassays were examined. Theoretical modeling of the dose-response curves for such assays allowed for optimization of experimental conditions. Through the examination of experimental and theoretical results generalizations could be made as to the ability of capillary electrophoretic immunoassays to achieve low detection limits. An experimental detection limit of 310 pM, corresponding to 2100 molecules, was achieved. A minimum theoretical detection limit for the antibody of interest was approximated to be 125-525 pM depending on the standard deviation. An overview of the optimization process is given as well as commentary on theoretical predictions.