Faster and Easier Radioimmunoassay of Digoxin
- 1 March 1974
- journal article
- research article
- Published by Oxford University Press (OUP) in Clinical Chemistry
- Vol. 20 (3) , 343-347
- https://doi.org/10.1093/clinchem/20.3.343
Abstract
We describe an improved radioimmunoassay method for serum digoxin, with 125I as tracer, to eliminate the problems that endanger the validity of this assay: apparent instability of tracer, time-dependence of charcoal separation of free and bound fractions, and influence of sample-to-sample differences on results. Principal innovations leading to a more rugged and reliable test are the use of (a) a stable [125I] tyros ine-methyl-ester of digoxin, (b) ammonium sulfate to separate bound and free fractions, (c) a fresh serum pool for the standard curve, and (d) individual specimen blanks. Results compare favorably with those of the properly-controlled, original tritium method of Smith et al. [New Engi. J. Med. 281, 1212 (1969)] in terms of digoxin values, while the method excels it in convenience and speed. Between-run precision is 11% (CV) over the range of interest (mean, 2.7 µg/liter), sensitivity is 0.2 µg/liter, and recovery of added digoxin averages 102%.Keywords
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