Multiplex array analysis is a powerful technique enabling the simultaneous detection and quantitation of multiple analytes in a single sample. Using color coded microspheres, these tests can be carried out at flow cytometers. Cyto-Plex microspheres provide up to ten levels of red fluorescent intensities for analysis of ten different analytes. The Cyto-Plex microsphere kits consist of uniform particles with fluorescence intensities that are completely separated from each other. The microspheres are all the same size and have high-density carboxylated surfaces, providing very low non-specific binding and a consistent, uniform surface for coupling of a wide variety of anitbodies, nucleic acids and other biomolecules. Cyto-Plex microspheres have maximum emission at 700 nm, and can be excited with either 488 nm or 633 nm. Emission can be collected in 650 – 670 nm detector. Since there is little or no emission in FL1 and FL2, probes utilizing either of these channels can be effectively used as reporters.