Patent ID: 8216856

Claim:
A detectable molecule comprising a biospecific binding reactant attached to a luminescent lanthanide chelate comprising a lanthanide ion and a chelating ligand of the formula (I) wherein, a) R 1A and R 1B are independently of each other selected from the group consisting of hydrogen, methyl, ethyl, —COOH, —COO—, —CH 2 COOH, —CH 2 COO—, hydroxyl and OR 2 ; b) R 2 is selected from the group consisting of —CH 3 , —C(CH 3 ) 3 , —C(CR 4 ) 3 , wherein R 4 is an alkyl with 1 to 6 carbon atoms, —CH 2 COOH, —CH 2 COO—, c) R 3 is a linker for coupling to said biospecific binding reactant selected from the group consisting of thiourea (—NH—CS—NH—), aminoacetamide (—NH—CO—CH 2 —NH—), amide (—NH—CO— and —CO—NH—), aliphatic thioether (—S—), disulfide (—S—S—) and 6-substituted-1,3,5-triazine-2,4-diamine; and d) the lanthanide ion is selected from the group consisting of europium(III), terbium(III), dysprosium(III) and samarium(III).