Electrochemical detection of trinitrotoluene in water samples based on a natural mineral attapulgite modified electrode

Abstract

This study reports an electrochemical approach for an assay of trinitrotoluene (TNT) in water samples. This assay is based on the electrochemical reduction of TNT at a natural mineral, attapulgite, modified glassy carbon (attapulgite/GC) electrode. To detect TNT, TNT is first accumulated on an attapulgite/GC electrode by holding the electrode at a constant potential of 0V versus Ag/AgCl for 40s in an aqueous TNT solution. Next, the attapulgite/GC electrode with accumulated TNT is transferred to a fresh PBS solution (0.1M, pH7.0, without TNT), where the TNT reduction current at −0.36V versus Ag/AgCl in a linear sweep voltammogram (LSV) shows a linear response to TNT concentrations in the aqueous solution from 1 to 200ppb with a correlation coefficient of 0.998 and a detection limit of 0.2ppb at a signal/noise (S/N) of 3. Moreover, the attapulgite/GC electrode displays high stability, good anti-interference ability to certain common interferents in real water samples, and reliable detection precision. Along with the abundance, low price, and environmental friendliness of attapulgite, the developed electrochemical sensor for the TNT assay has great potential for the practical determination of TNT levels in real water samples.