Study of the electrochemical behavior of mitoxantrone and its determination at a Co-C modified ultramicroelectrode.

In 0.005 mol dm-3 Tris-0.05 mol dm-3 NaCl buffer solution (pH 7.10), the electrochemical behavior of mitoxantrone was studied by linear-sweep voltammetry and cyclic voltammetry at a Co-carbon fiber ion implantation modified ultramicroelectrode. A sensitive reduction peak was obtained. The peak potential was -0.798 V (vs. SCE), the peak current was proportional to the concentration of mitoxantrone over the range of 2.0 x 10(-7)-6.0 x 10(6) mol dm-3 and the detection limit was 4.2 x 10(-8) mol dm-3. This method was applied to the direct determination of mitoxantrone in urine. Recoveries were in the range 95.4-105.8%. The reduction process was quasi-reversible with absorptive characteristics at a Co-C ultramicroelectrode. According to Laviron's theory, the electrode reaction rate constant ks and the electron transfer alpha of mitoxantrone were 4.4 s-1 and 0.48, respectively. The composition and depth distribution of elements on the surface of the Co-C ultramicroelectrode were determined by Auger electron spectroscopy. The experiments showed that Co was implanted into the surface of the carbon fiber, and the Co-C ultramicroelectrode had good stability and reproducibility.