The lanthanides provide 37 stable isotopes for measuring antigen-bound antibodies, MHC tetramers and nucleic acid probes with high sensitivity. Indium provides two additional low-sensitivity channels for highly expressed markers, and quantum dots provide one additional channel (cadmium). Rhodium and iridium, as DNA intercalators, register a cell event. Platinum, in the form of cisplatin:sulfur complexes, is used as a viability marker. Iodine, as iodo-deoxyuridine, is used for cell cycle measurements. Six palladium isotopes allow for mass tag “barcoding” and multiplexed measurement of samples.