The invention provides methods and kits for detecting the presence of, the amount of, or the concentration of a substantially non-emitting metal in a sample by a) providing a sensitizer to a chelator of the substantially non-emitting metal thereby creating a sensitized-metal complex; b) adding an unsensitized chelate, and c) detecting a signal from the unsensitized chelate. The substantially non-emitting metal may be gadoliniumn and may exist in complex with a chelator. The unsensitized chelate may be terbium (Tb) or europium (Eu) and the detecting a signal may be performed by fluorescence.