University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Thyroxine

  • IUPAC Name: 2-amino-3-[4-(4-hydroxy-3,5-diiodophenoxy)-3,5-diiodophenyl]propanoic acid
  • Molecular Formula: C15H11I4NO4
  • CAS Registry Number: 300-30-1
  • InChI: InChI=1S/C15H11I4NO4/c16-8-4-7(5-9(17)13(8)21)24-14-10(18)1-6(2-11(14)19)3-12(20)15(22)23/h1-2,4-5,12,21H,3,20H2,(H,22,23)
  • InChI Key: XUIIKFGFIJCVMT-UHFFFAOYSA-N

@ ChemSpider@ NIST@ PubChem

Citations 7

"Flow Injection Method For The Determination Of Thyroxine By Inhibition Of Glutamate Dehydrogenase"
Anal. Chim. Acta 2000 Volume 411, Issue 1-2 Pages 45-49
T. Ghous and A. Townshend

Abstract: Thyroxine is an important hormone and is reported to be an inhibitor of glutamate dehydrogenase (G1DH). This inhibitory effect of thyroxine is used to develop a simple and highly reproducible flow injection method for its determination. The change in NADH absorbance at 340 nm in the presence of the enzyme and thyroxine is measured on-line and related to the percent inhibition (%I) which increases with inhibitor concentration. The relative standard deviation is 1.8% for 8 x 10^-6 M thyroxine (n=7) and the 3s limit of detection is 9 x 10^-7 M. The linear equation over the range 0.2-8 x 10^-5 M was %I=4.9+8.97 x 10(5) [thyroxine, M], and the correlation coefficient was 0.998 (n=7).
Biological Immunoassay Spectrophotometry Indirect

"Flow Injection Analysis With Chemiluminescence Detection In The Determination Of Fluorescein- And Fluorescamine-labeled Species"
Anal. Chim. Acta 1983 Volume 145, Issue 1 Pages 203-206
V. K. Mahant, J. N. Miller and H. Thakrar

Abstract: Many fluorescence immunoassays have indifferent limits of detection because of the background signals from biological samples. Scattered light contributes to this background, but can be eliminated by exciting conventional fluorescent labels via chemiluminescence reactions involving bis(2,4,6-trichlorophenyl)oxalate. This reaction, whose rate can be controlled, is conveniently used in a flow injection system with a luminometer as a detector. Such a system is applied to study fluorescein- and fluorescamine-labelled species at concentrations as low as 10^-11 M (ca. 0.5 pg in a 100 µL sample). The effects of antibodies on the luminescence signals from labelled antigens are discussed.
Clinical analysis Chemiluminescence Immunoassay

"Flow Injection Enzyme Immunoassay Of Haptens With Enhanced Chemiluminescence Detection"
Anal. Chim. Acta 1990 Volume 237, Issue 2 Pages 285-289
A. A. Arefyev, S. B. Vlasenko, S. A. Eremin, A. P. Osipov and A. M. Egorov

Abstract: A non-equilibrium flow injection enzyme immunoassay for thyroxine (model hapten) is described, involving affinity separation of the immunocomplex of horseradish peroxidase-labelled antibodies and antigen from the free labelled antibodies. The analyte solution and peroxidase - IgG conjugate were introduced by a two-channel microinjector into two streams of 0.05 M Tris - HCl buffer (pH 8.5) containing 0.05% of polysorbate 20. The reaction zone was incubated, the stream was combined with solution of luminol, p-iodophenol and H2O2 and the mixture was fed into the flow cell of an LKB-1250 luminometer. The chemiluminescence intensity was measured for at least 3 min. The detection limit of the antigen was 12 pM within 5 min and the coefficient of variation was 10%.
Chemiluminescence Immunoassay Detection limit

"Improved Fully Automated Continuous-flow System For Immunoassays"
Ann. Clin. Biochem. 1981 Volume 18, Issue 5 Pages 287-294
Adel A A Ismail, Peter M West, David J Goldie, Anthony C Poole*

Abstract: A modification to the Southmead continuous-flow automated immunoassay system enables the bound ligand fraction to be quantitated. The bound fraction is sequentially collected, washed, and then eluted from the separating device as a bolus. The misclassification error at separation is of the order of 0.6%, and sample-to-sample interaction is negligible. The application of the modified system to the radioimmunoassay for thyroxine at a rate of 60 samples per hour is described, and satisfactory assay characteristics and performance are documented. The application of the Southmead system to the enzyme immunoassay of thyroxine and to assays for other ligands is discussed.
Clinical analysis Immunoassay

"Continuous-flow Enzyme Immunoassay For Thyroxine In Serum"
Clin. Chem. 1981 Volume 27, Issue 5 Pages 738-741
JP Nolan, G DiBenedetto and NJ Tarsa

Abstract: We have evaluated a fully automated thyroxine assay involving the use of a homogeneous enzyme assay and a Technicon AutoAnalyzer II continuous flow system. Comparison by regression analysis with a thyroxine radioimmunoassay kit method gave a slope of 0.82 and a y- intercept of 7.81 µg/L (SE 0.86µg/L, r = 0.95). Within- run precision yielded CVs of 1.0-6.1%, between-day CVs were 2.0-14.4%; within-day precision showed a mean variance of 7.81 µg/L. Mean analytical recovery was 96.1%. Bilirubin, hemoglobin, and lipemia interfered with quantitation of results when their concentrations exceeded 50 mg/L, 300 mg/L, and 5 g/L, respectively. The reference interval for euthyroid status was calculated to be 50-110 µg/L. Sensitivity was 5.0 µg/L with a mean carryover of 1.65%. Current reagent and labor costs for enzyme immunoassay ($0.40) were less than for the manual radioimmunoassay procedure ($0.40) were less than for the manual radioimmunoassay procedure ($1.70). The assay is economical, simple to perform, and amenable to high-throughput thyroid screening in the routine laboratory.
Blood Serum Clinical analysis Immunoassay Enzyme Technicon Air segmentation Method comparison

"Stabilized Filter-supported Bilayer Lipid Membranes (BLMs) For Automated Flow Monitoring Of Compounds Of Clinical, Pharmaceutical, Environmental And Industrial Interest"
J. Autom. Methods Manag. Chem. 1997 Volume 19, Issue 1 Pages 1-8
DIMITRIOS P. NIKOLELIS and CHRISTINA G. SIONTOROU

Abstract: The method and apparatus for the preparation of phosphatidylcholine/dipalmitoylphosphatidic acid membranes, containing enzymes or antibodies, cast on glass microfiber or polycarbonate ultrafiltration membranes are described [cf. Anal. Chem., 1995, 67, 936; Electroanalysis (N.Y.), 1995, 7, 531, 1082]. The membranes were used in flow injection amperometric determinations of (i) substrates (e.g., acetylcholine, penicillin and urea) of hydrolytic enzymes, and (ii) antigens (e.g., thyroxine and triazine herbicides).
Pharmaceutical Environmental Industrial Clinical analysis Biochemical analysis Amperometry Supported lipid membrane Polycarbonate membrane Glass microfiber

"An Investigation On The Catalytic Mechanism Of Enhanced Chemiluminescence: Immunochemical Applications Of This Reaction"
J. Biolumin. Chemilumin. 1989 Volume 4, Issue 1 Pages 164-176
S. B. Vlasenko, A. A. Arefyev, A. D. Klimov, B. B. Kim, E. L. Gorovits, A. P. Osipov, E. M. Gavrilova, A. M. Yegorov

Abstract: Flow injection enzyme immunoassays were developed for (i) thyroxine (I) and (ii) IgG (II) with use of enhanced chemiluminescence. (i) Sample solution (30 µL) and peroxidase - rabbit IgG conjugate (30 µL) were mixed with 0.05 M Tris - HCl buffer (pH 8.5) and passed through an affinity column of bovine serum albumin - I conjugate immobilized on CNBr-Sepharose. The eluate was combined with luminol, 4-iodophenol and H2O2 and the chemiluminescence was measured for 3 min. (ii) Sample solution (200 µL) was mixed with peroxidase - II conjugate (200 µL), and the mixture was allowed to react with a polystyrene bead coated with rabbit antibodies to human II. The bead was transferred to the cell of the luminometer and mixed with luminol, 4-iodophenol and H2O2 before measurement of luminescence. The detection limits were 10 nM-I and 1 nM-II.
Biological Chemiluminescence Immunoassay Buffer Column Immobilized reagent Sepharose beads Polystyrene beads