title: Automated particle-counting immunoassay for digoxin.
abstract: We describe a non-radioisotopic automated immunoassay for serum digoxin in the therapeutic range at 50 samples per hour by use of the particle-counting immunoassay technique and a special reagent, rheumatoid factor. Digoxin is determined by evaluating its inhibitory activity on the agglutination of digoxin-coated latex particles. The agglutinating system consists of the anti-digoxin IgG mixed with rheumatoid factor. This anti-IgG autoantibody reacts with IgG when they are aggregated or bound to a surface. Interference by serum proteins was prevented by pepsin digestion at 37 degrees C. Correlation with radioimmunoassay was r = 0.94 for 109 samples with concentrations between 0 and 5.7 micrograms/L. Analytical recovery overall averaged 102%. Within-assay precision (CV) ranged from 12.5% at 0.96 micrograms/L to 4.4% at 2.97 micrograms/L; between-assay precision varied from 8.4% at 0.75 micrograms/L to 5.8% at 2.92 micrograms/L.
mesh_terms: D000936:Antigen-Antibody Complex; D001322:Autoanalysis; D003429:Cross Reactions; D004077:Digoxin / Q000097:blood*; D006241:Haptens; D006801:Humans; D007118:Immunoassay; D007074:Immunoglobulin G; D007202:Indicators and Reagents; D012217:Rheumatoid Factor
chemical_list: D000936:Antigen-Antibody Complex; D006241:Haptens; D007074:Immunoglobulin G; D007202:Indicators and Reagents; D004077:Digoxin; D012217:Rheumatoid Factor