title: Co-fluorescence of europium and samarium in time-resolved fluorimetric immunoassays.
abstract: In the presence of an excess of Y3+, the fluorescence intensities of Eu3+ and Sm3+, chelated with benzoyltrifluoroacetone (BTA) or thenoyltrifluoroacetone (TTA) in an aqueous solution containing 1,10-phenanthroline, were increased by factors ranging from 209- to 811-fold. This co-fluorescence phenomenon was used in a highly sensitive time-resolved fluorimetric detection of the lanthanides, Eu3+ and Sm3+. The detection limits of Eu3+ in the BTA- and TTA-based solutions were 4 and 15 fmol dm-3, respectively. The detection limits of Sm3+ were 0.11 and 0.12 pmol dm-3, respectively. The co-fluorescence enhancement systems were also applied in the double-label time-resolved fluorimetric immunoassay of luteinizing hormone and follicle stimulating hormone using specific antibodies labelled either with Eu3+ or Sm3+. The co-fluorescence enhancement solution was superior as compared with the commercial 'direct' fluorescence enhancement solution based on the acidic solution of beta-naphthoyltrifluoroacetone, trioctylphosphine oxide and Triton X-100, in respect to the signal level obtained and the sensitivity. It is suited to time-resolved fluorimetric immunoassays in which particularly high detection sensitivities are required, and it can also be used in double-label assays employing Eu3+ and Sm3+ chelate labels.
authors.affiliation: Institute of Atomic Energy of China, Analytical Chemistry Laboratory, Beijing, People's Republic of China.
authors.forename: Y Y
authors.initials: YY
authors.lastname: Xu
authors.forename: I
authors.initials: I
authors.lastname: Hemmilä
authors.forename: V M
authors.initials: VM
authors.lastname: Mukkala
authors.forename: S
authors.initials: S
authors.lastname: Holttinen
authors.forename: T
authors.initials: T
authors.lastname: Lövgren
mesh_terms: D005063:Europium; D005453:Fluorescence; D005455:Fluorescent Antibody Technique; D005640:Follicle Stimulating Hormone / Q000032:analysis; D007986:Luteinizing Hormone / Q000032:analysis; D010618:Phenanthrolines; D012493:Samarium; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D015019:Yttrium
chemical_list: D010618:Phenanthrolines; D012493:Samarium; D005063:Europium; D015019:Yttrium; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C025205:1,10-phenanthroline