Comparison of analysis of digoxin in cardiac patients by HPLC and RIA.

A sensitive and selective high-performance liquid chromatographic-post column derivatization (HPLC-PC) method was used to determine the digoxin levels in the sera of cardiac patients and was compared to the values obtained from analysis of the same samples by conventional radioimmunoassay (RIA) procedures. A statistical comparison of the results obtained by the RIA and HPLC-PC methods showed an overall lower assay value for the samples determined by the HPLC-PC method. High cross-reactivity values for the metabolites of digoxin were determined using RIA kits currently available for digoxin measurements.