Voltammetric Characterisation of Anticancer Drug Irinotecan

Electrochemical reduction of irinotecan was investigated on a static mercury drop electrode using square-wave voltammetry. The mechanism of irinotecan electroreduction is a complex, pH- dependent, quasireversible process and includes the transfer of two electrons and two protons. In acidic medium, the first electron transfer reaction is followed by the chemical reaction, and the product of this chemical reaction undergoes further electrochemical reduction at more negative potentials. Both irinotecan and the product of its reduction adsorb on the mercury electrode surface. Based on the adsorptive character of irinotecan, a new adsorptive stripping square-wave voltammetric method for its electroanalytical determination has been proposed. The voltammetric response could be used to determine irinotecan in the concentration range from 1×10−7 mol/L to 1.5×10−6 mol/L and from 5×10−9 mol/L to 1.2×10−7 mol/L, if the accumulation time is 20 s and 300 s, respectively. The calculated limit of detection for irinotecan was found to be 8.7×10−9 mol/L (if tacc=300 s).