B 1701b Berlin blue, spazial grade Cas 12240-15-2 - used to differentiate slow versus fast cycling cells by methods that monitor iron oxide particle labeling dilution thru cell division. B 1701b Berlin blue, spazial grade Cas 12240-15-2 - used as an antidote for certain kinds of heavy metal poisoning, e.g., by thallium and radioactive isotopes of caesium.