Use of capillary electrophoresis-based competitive immunoassay for a largemolecule

A systematic study on the optimization of capillary electrophoresis-based i mmunoassay (CEIA) was performed using bovine serum albumin (BSA) and monocl onal anti-BSA. The immunocomplex could not be resolved from free BSA or ant i-BSA with UV detection. When fluorescein isothiocyanate-labeled BSA (FITC- BSA) was used as tracer, the free and bound FITC-BSA were well separated gi ving definite peaks with laser induced fluorescence detection. The factors affecting the separation of the free and bound FITC-BSA, including voltage, pH and ionic strength of the running buffer, were systematically analyzed. Competitive CEIAs were demonstrated in uncoated and coated capillaries wit h whole or Fab fragment of the antibody. The coefficient of variation for t he quantification of BSA in coated capillary was less than that in uncoated capillary. This study demonstrated that competitive CEIA could be applied to quantify high-molecular-mass protein in biological fluids. (C) 1999 Publ ished by Elsevier Science B.V. All rights reserved.