Cyclic voltammetry as a screening tool for the fungal degradation of 2,4,6-trinitrotoluene in aqueous media

The use of an electrochemical technique based on cyclic voltammetry (CV) that can be implemented to monitor the degradation of the important nitroaromatic explosive 2,4,6-trinitrotoluene (TNT) in aqueous media when in contact with a microorganism is presented. The microorganism used in this study was an isolated fungus belonging to the Aspergillus genus. In the degradation experiments, during the first 21 days of exposure of the fungal growth to a 68 mg L^?1 TNT aqueous stock solution, the analyte concentration decreased by 44% to 38 mg L^?1 before plateauing through the 58th day of the study. Statistical figures of merit of the technique included linearity in the 1–92 mg L^?1 range and correlation coefficients above 98% for the three reduction peaks of TNT, a limit of detection (LOD) of 3 mg L^?1, a limit of quantification of 10 mg L^?1 and a method precision of 3.8% relative standard deviation (%RSD). Day-to-day and week-to-week repeatability were low at 5.1%RSD and 5.8%RSD, respectively. The results herein exhibit first-order kinetics for the ‘ortho’ nitro group. A clear to yellow colour transition in the control solution and fungi samples suggests the appearance of a TNT metabolite. UV-Vis spectrophotometry supports the presence of a possible derivative of TNT in the fungi samples.