QUANTITATION OF DIGITOXIN, DIGOXIN, AND THEIR METABOLITES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING PULSED AMPEROMETRIC DETECTION

A novel detection method for the cardiac glycosides digitoxin, digoxin, and their metabolites is described. Both isocratic and gradient water-acetonitrile elutions were employed with an octadecylsilane column. The effluent was monitored by integrated pulsed amperometry in an alkaline medium (pH>12) by adding sodium hydroxide post-column. Using isocratic elution, peak responses were linear from 10 to 70 ng, with lower limits of detection between 4 and 15 ng. This method allows easy modification of well-estalished high-performance liquid chromatographic systems, as well as comparable sensitivity and greater selectivity than UV detection.