Adaptation of the Syva EMIT-cad digoxin enzyme immunoassay technique on the Instrumentation Laboratory Multistat-III microcentrifugal analyzer.
The Syva EMIT-cad digoxin assay, a three-step manual enzyme immunoassay (EIA) technique, was adapted to be run on the Multistat-III microcentrifugal analyzer. This adaptation permits semiautomation of the procedure along with a sizable reduction in sample and reagent volumes. A 5-min pretreatment of a 100-microliters sample with 0.5 N NaOH is followed by a 15-min incubation with 625 microliters of the anti-digoxin antibody and enzyme substrate reagent. A 198 microliters aliquot of this mixture and 65 microliters of the second digoxin enzyme conjugate reagent are loaded separately onto the rotor by the loader module in two successive loading cycles. The final 30-min incubation is initiated by rotation in the analyzer module. Intraassay performance [coefficient of variation (CV)] using patient samples (n = 10) is 10.5% at 0.6 ng/ml, 10.2% at 1.4 ng/ml, and 10.5% at 2.9 ng/ml. Interassay performance (CV) using the Hyland Omega II (1.4 ng/ml) and Omega III (2.8 ng/ml) ligand quality control sera (n = 13) is 12.3% and 9.7%, respectively. Assay linearity is excellent up to 5.0 ng/ml. Correlation of the results with a radioimmunoassay (RIA) method is EMIT = 0.98 RIA + 0.02, r2 = 0.92, standard error of estimate = 0.23 (52 patient samples). The time required for a normal run (10 patients) or a single urgent analysis is approximately 75 min.
D001322:Autoanalysis; D002498:Centrifugation / Q000379:methods; D004077:Digoxin / Q000097:blood*; D006801:Humans; D007124:Immunoenzyme Techniques; D008832:Microchemistry; D011863:Radioimmunoassay / Q000379:methods
D004077:Digoxin