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 wate r-acetonitrile elutions were employed with an octadecylsilane column. The effluent was monitored by integrated pulsed amperometry in an alka line medium (pH>12) by adding sodium hydroxide post-column. Using isoc ratic elution, peak responses were linear from 10 to 70 ng, with lower limits of detection between 4 and 15 ng. This method allows easy modi fication of well-estalished high-performance liquid chromatographic sy stems, as well as comparable sensitivity and greater selectivity than UV detection.