Adsorptive stripping voltammetry of bleomycin

In 0.05 M H2SO4 solution, two reductive peaks, P-1 and P-2, of bleomycin were obtained. The peak potentials E-P1 and E-P2 were -0.83 and -1.09 V (versus Ag/AgCl), respectively. The sensitivity of P-2 was much higher than that of P-1. The peak current of P-2 was proportional to the concentration of bleomycin over the range 1.0 X 10(-9)-1.0 X 10(-7) M with a detection limit of 5.0 X 10(-10) M using adsorptive voltammetry at an accumulation time of 120 s (E-i = -0.80 V). The behaviour of the reduction wave was studied and applied to the determination of bleomycin in mouse serum. The reduction process of P-1 was irreversible with adsorptive characteristics and the adsorption behaviour obeyed the Frumkin adsorptive isotherm. The adsorptive coefficient beta was 8.9 X 10(5), the interaction factor alpha was 0.94 acid the Gibbs energy adsorption Delta G degrees was -33.93 kJ mol(-1). P-2 was an irreversible adsorption peak with catalytic hydrogen properties.