title: Development of a highly sensitive and selective microplate chemiluminescence enzyme immunoassay for the determination of free thyroxine in human serum.
abstract: A microplate chemiluminescence enzyme immunoassay (CLEIA) with high sensitivity, selectivity and reproducibility was developed for the determination of free thyroxine (FT4) in human serum. A competitive assay has been utilized with horseradish peroxidase (HRP) labeled thyroxine analog in the chemiluminescence (CL) detection. The CL signal produced by the emission of photons from luminol was directly proportional to the amount of analyte. The linear range was 0.45-7.5 ng dL(-1 )and the detection limit was 0.09 ng dL(-1). Experimental conditions, such as temperature, pH, incubation time, titration level and other relevant variables upon the CL signal have been examined and optimized. A coefficient of variance of less than 16% was obtained for intra- and inter-assay precision. The present method has been successfully applied to the analysis of FT4 in human serum. The positive and negative coincidence ratios are satisfactory. Good correlations were obtained between the results by the proposed method and radioimmunoassay (RIA), as well as a Bayer ACS-180SE detection system.
authors.affiliation: The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Jin-Ming
authors.initials: JM
authors.lastname: Lin
authors.forename: Xitang
authors.initials: X
authors.lastname: Ying
mesh_terms: D002138:Calibration; D006735:Horseradish Peroxidase / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007124:Immunoenzyme Techniques / Q000379:methods*; D008163:Luminescent Measurements; D011136:Polysorbates; D012016:Reference Values; D012680:Sensitivity and Specificity; D012980:Sodium Salicylate / Q000037:antagonists & inhibitors; D013696:Temperature; D013974:Thyroxine / Q000097:blood*; D017186:Titrimetry; D014238:Trichloroacetic Acid / Q000037:antagonists & inhibitors
chemical_list: D011136:Polysorbates; D014238:Trichloroacetic Acid; D006735:Horseradish Peroxidase; D013974:Thyroxine; D012980:Sodium Salicylate