Homogeneous enzyme immunoassay of serum digoxin with use of a bichromatic analyzer

We applied the Enzyme Multiplied Immunoassay Technique (EMIT; Syva Corp., Palo Alto, CA) for determination of serum digoxin to the ABA-100 bichromatic analyzer. Assay conditions were almost exactly as prescribed for the manual procedure, but the ABA-100 offers high automation, smaller reagent volumes, and shorter reaction time. Precision studies gave CV's of less than 10%. Sixty patients' samples, analyzed for digoxin by radioimmunoassay and this enzyme immunoassay, gave a correlation (r) of 0.941. Results obtained with the ABA-100 were apparently slightly higher. One kit provides reagents for 250 assays, as compared to 70 assays with the manual procedure. In an emergency situation a result will be available about 60 min after the patient's sample is received; one operator can analyze about 120 samples in 8 h.