A process for synthesizing and separating secretory IgA from a mixture of IgA monmer and IgA dimer is provided. The process includes covalently binding affinity tagged or epitope tagged recombinant secretory component to the IgA dimer in the mixture and binding the affinity tagged or an epitope tagged secretory IgA to immobilized moieties on the solid phase support resin to which the affinity tag or epitope tag binds and then eluting the affinity tagged or an epitope tagged secretory IgA with release buffer. A process for synthesizing and separating secretory IgM from a mixture of IgM and other plasma proteins is also provided. The process includes covalently binding affinity tagged or an epitope tagged recombinant secretory component to the IgM in the mixture and binding the affinity tagged or an epitope tagged secretory IgM to immobilized moieties on the solid phase support resin and then eluting the peptide tagged secretory IgM with a release buffer.