Rapid immunoassays using capillary electrophoresis with fluorescence detection

Capillary electrophoresis (CE) is another technique that may be useful in performing rapid, automated immunoassays. Several groups have utilized CE for separations involving ligands, proteins, and their complexes. Most relevant to the present work, Nielson et al. demonstrated that human growth hormone (HGH), anti-HGH, and complexes of HGH and anti-HGH could be resolved by free solution capillary zone electrophoresis (CZE) with UV detection within 5 min. Fluorescent tags are a logical choice for a CZE-based immunoassay since laser-induced fluorescence (LIF) has proven to be a powerful method for detection of trace levels of compounds separated by CZE. In this paper, we describe efforts aimed at combining the selectivity of immunoassay methods with the speed, automation, and sensitivity of CZE-LIF. Two types of CZE-based immunoassay, one noncompetitive and the other competitive, are described.