Because of its small size, Ru can be easily conjugated to any
protein ligand using standard chemistries without affecting immunoreactivity or solubility
of the protein. In a typical agent-detection assay, a sample is added to a mixture of capture antibody-coated paramagnetic beads and a Ru-conjugated detector antibody. After a short incubation period, the analyzer draws the sample into the flow cell, captures and washes the magnetic beads, and measures the electrochemiluminescent signal.