Determination of 6-mercaptopurine in the presence of uric acid using modified multiwall carbon nanotubes-TiO2 as a voltammetric sensor

In this work, a multiwall carbon nanotubes modified electrode (prepared by incorporating TiO2 nanoparticles with p-aminophenol as a mediator) was used as voltammetric sensor for the determination of 6-mercaptopurine (6-MP) in the presence of uric acid (UA). The voltammograms of 6-MP and UA in a mixture can be separated from each other by differential pulse voltammetry with a potential difference of 380 mV at a scan rate of 10 mV s-1. These conditions are sufficient to allow for the determination of 6-MP and UA both individually and simultaneously. The electrocatalytic currents increase linearly with 6-MP concentration in the ranges of 0.09350 mu mol L-1 (two linear segments with different slopes). The detection limit for 6-MP was 0.065 mu mol L-1. The RSD% for 1.0 and 15.0 mu mol L-1 6-MP were 0.7%, and 1.2%, respectively. The kinetic parameters of the system were determined using electrochemical approaches. The method was successfully applied for the determination of 6-MP in drug sample, and 6-MP plus UA in urine samples. Copyright (c) 2011 John Wiley & Sons, Ltd.