Compound separating and inverse screening method through capillary electrophoresis two-time on-line reaction

The invention relates to a compound separating and inverse screening method through capillary electrophoresis two-time on-line reaction, and belongs to the technical field of biological separation and analysis. The method includes the steps that reactants are subjected to capillary zone electrophoresis, the first reactant, a first-section electrophoretic buffer solution, the second reactant, a second-section reactant and the third reactant are injected as samples, subjected to on-line reaction and mixed to form the compound, then the compound passes through a window to be detected; the migration rate of the first reactant and the second reactant is small, the migration rate of the third reactant is large, and the reactants are protein and ssDNA; when the compound is separated, the first reactant and the second reactant are protein or ssDNA at the same time, and the third reactant is different from the first reactant and the second reactant; during inverse screening, ssDNA reacts with inverse screening protein