Adsorptive stripping voltammetric determination of low levels of daunorubicin
The surface-active properties of the antitumour agent daunorubicin are exploited for developing a highly sensitive adsorptive stripping voltammetric method for the determination of trace amounts of this compound. Effective pre-concentration is obtained at the hanging mercury drop and carbon-paste electrodes, with the surface species being measured via its reduction or oxidation, respectively. The former yields more sensitive and reproducible results. After a 5 min pre-concentration, a 50-fold enhancement of the response is observed, resulting in a detection limit near 1 × 10–9M. Cyclic voltammetry is used to explore the interfacial and redox behaviours. The optimum conditions include a pre-concentration potential of –0.30 V and a pH 4.4 acetate buffer solution. The relative standard deviation at the 1.5 × 10–7M level is 1.5%. Possible interferences (electroinactive surfactants, co-administered drugs) are investigated. The applicability to direct assays of urine, and simultaneous measurement of methotrexate and daunorubicin, is described.