Quantitation of the antineoplastic agent indicine-N-oxide in human plasma by differential pulse polarography

A sensitive and reproducible differential pulse polarographic method of analysis was developed for indicine-N-oxide (NSC 132319) in human plasma. Lyophilized plasma is extracted with methanol, and the extract is chromatographed over partially deactivated aluminum oxide and reversed-phase silica gel columns. Indicine-N-oxide is eluted from the silica gel column with 25% aqueous methanol and quantitated by differential pulse polarography by measurement of the peak current at -0.72 +/- 0.03 v (versus the saturated calomel electrode). Recovery of indicine-N-oxide from plasma was 88 +/- 7% (SD) in the 1-20-microgram/ml range. The method was linear over the range of 0.5-10 microgram/ml of pH 4.6 buffer.