Adsorptive stripping voltammetric detection of daunomycin at mercury and bismuth alloy electrodes

We investigated the analytical response of daunomycin, an effective drug used for cancer chemotherapy, at different types of electrodes. The following five different materials for the electrodes have been compared: hanging mercury drop, gold, gold/bismuth, gold/mercury and silver mercury. Especially at the hanging mercury drop electrode and also at the silver/mercury and gold/mercury amalgam electrode, nicely shaped cyclic voltammograms with nearly no peak separation could be found whereas both the gold and the gold/bismuth electrode showed a significant peak separation. The linear dependency to the scan rate of the signal of all the electrodes is a hint for adsorption rather than diffusion control. In adsorptive stripping voltammetry it could be shown that especially the gold/bismuth alloy (4 % Bi) has a great linear calibration range of daunomycin, whereas the linear range at the hanging mercury drop electrode is surprisingly limited. The reason for the advantageous properties of the gold/bismuth alloy in adsorptive stripping analysis can probably be addressed to sufficiently strong and particularly constant adsorption at low daunomycin concentrations at the electrode surface. Hence, the gold/bismuth electrode can be recommended for adsorptive stripping voltammetry of trace amounts of daunomycin.