The Galvanostatic Reduction on Modified Platinum Electrode and Determination of Trinitrotoluene in Neutral Solution

Abstract

The study of the electrochemical reduction on acetonitrile modified platinum electrode and determination of trinitrotoluene (TNT) in neutral solution by simple galvanostatic technique is presented here. The obtained potential-time responses on the applied constant cathodic current pulses showed two potential transitions before achieving the steady-states, referring to the multi-step reduction process of nitro groups in TNT molecule. The calibration curves of the dependence of the square root of the first transition time (tau(0.5)) on the TNT concentration were linear in the ranges 4.4 - 303.8 mu M and 0.09 - 4.40 mu M for applied constant current of 0.1 mA. The detection limit was 0.09 mu M. The method was tested in the river water. The results indicated the sensitivity of the galvanostatic method for TNT determination in the environmental samples. From the first transition on the E-t curves the characteristics important for the understanding the mechanism of the reduction process were obtained. It was found that four electrons are involved in the reduction process of the first nitro group, indicating that the reduction product in a neutral electrolyte is hydroxylamine.