ENZYME IMMUNOMETRIC ASSAY FOR L-THYROXINE USING DIRECT ULTRAVIOLET-IRRADIATION

A new enzyme immunometric assay for L-thyroxine using uv irradiation a s a cross-linking procedure is described. L-Thyroxine in plasma sample s is immunocaptured by a monoclonal anti-L-thyroxine antibody coated o n 96-well microtiter plates, After uv irradiation and methanol treatme nt, the covalently linked L-thyroxine is measured using the same monoc lonal anti-L-thyroxine antibody labeled with acetylcholinesterase. A m inimal detectable concentration of 4.8 nmol/liter was observed with a coefficient of variation less than 16% in the 20-320 nmol/liter. Speci ficity of the assay was very satisfying and a good correlation (r = 0. 959) was noted for 33 human plasma samples between this assay and a co mmercial competitive radioimmunoassay. (C) 1995 Academic Press, Inc.