title: A rapid semi quantitative capillary enzyme immunoassay for digoxin.
abstract: A rapid and sensitive enzyme immunoassay (EIA) which does not require highly trained personnel or specialised instrumentation is described for the estimation of digoxin in serum, plasma or whole blood samples. The method is based on the ability of digoxin in a clinical sample to inhibit the binding of urease-conjugated sheep-antidigoxin immunoglobulin to a glass capillary tube coated internally with a human serum albumin-digoxin conjugate. The bound enzyme activity can then be measured using a substrate solution containing urea and a pH indicator, most suitably bromocresol purple. The enzymic hydrolysis of urea produces ammonia which causes a vivid yellow to purple colour change in the pH indicator. Plasma samples from 92 patients receiving digoxin were screened in parallel with reference plasma containing 1.3 or 3.8 nmol/l digoxin. The results were available within a total test time of 30 min, and showed excellent correlation with those obtained by radioimmunoassay.
mesh_terms: D003429:Cross Reactions; D004077:Digoxin / Q000097:blood* / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques
chemical_list: D004077:Digoxin