Voltammetric Determination of Ecotoxic Nitro Compounds Using Polished Silver Amalgam Composite Electrode

Abstract

Voltammetric behavior of biologically active 5-nitro­benzimidazole (NB) and 2,4,6-trinitrophenol (TNP) was investigated using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) at a polished Ag amalgam composite electrode (p-AgSA-CE). The optimum conditions were found for their determination in Britton-Robinson buffer of pH 5.0 and 2.0 for NB and TNP, respectively. Unfortunately, due to inferior repeatability of measurements, the voltammetric method for NB could not be developed. A probable reason is the formation of a complex of NB with the epoxy resin on the electrode surface. The TNP calibration curves were linear in the concentration ranges 0.1–100 μmol l^–1 (DCV) and 2–100 μmol l^–1 (DPV), with the limits of quantification (L_Q) ≈ 0.1 and 1 μmol l^–1 for DCV and DPV, respectively. The applicability of the DCV method was verified by direct determination of TNP in model samples of drinking and river water, with L_Q ≈ 0.6 and 2 μmol l^–1, respectively.