Patent ID: 8722415

Claim:
A method of detecting a luminescent target ion in a sample comprising: a. Mixing a solution comprising modified magnetic microspheres with a solution comprising a target ion which is a luminescent ion selected from the group consisting of Eu, Tb, Am, U and combinations thereof and a solution comprising a second ligand to form a detection solution, wherein the magnetic microspheres have a non-reactive barrier selected from the group consisting of gold, carbon, oxide, polymer and combinations thereof are modified through attachment of a first ligand capable of forming a complex with the target ion and the second ligand wherein the first ligand is a co-ligand and the second ligand is an antenna ligand, and wherein the co-ligand is a compound selected from the group consisting of phosphine oxides, organophosphates, diglycolamides, bidentate imides and combinations thereof, and wherein one or more first ligand/target ion/second ligand complexes are formed on the surface of the magnetic microsphere in the detection solution; and b. performing Time-resolved laser fluorescence (TRLF) spectroscopy is used to illuminate the detection solution and detect the luminescent response from the ligand complex.