Voltammetric Determination of Selected Nitro Compounds at a Polished Silver Solid Amalgam Composite Electrode

Abstract

AbstractVoltammetric behavior of selected biologically active organic nitro compounds, namely 2‐nitrofluorene, picric acid (2,4,6‐trinitrophenol) and metronidazole, has been investigated using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) at a polished silver solid amalgam composite electrode (p‐AgSA‐CE). The optimum conditions have been found for their determination in a 1 : 1 mixture of methanol and aqueous Britton–Robinson buffer of pH 5.0 for 2‐nitrofluorene and in the aqueous Britton–Robinson buffer solutions of pH 2.0 and 4.0 for picric acid and metronidazole, respectively, with the limits of quantification (LQs) 4, 0.1 and 2 µmol L−1 (DCV at p‐AgSA‐CE) and 3, 1 and 4 µmol L−1 (DPV at p‐AgSA‐CE) for 2‐nitrofluorene, picric acid and metronidazole, respectively. An attempt to increase the sensitivity using adsorptive stripping voltammetry was not successful for all three test substances. For comparison, the UV‐vis spectrophotometric determinations of studied compounds have also been carried out in methanol for 2‐nitrofluorene (LQ≈1 µmol L−1) and in deionized water for picric acid (LQ≈3 µmol L−1) and metronidazole (LQ≈2 µmol L−1). Practical applicability of the newly developed voltammetric methods was verified on direct determination of the studied compounds in drinking and river waters with LQs around 10−6 mol L−1 for all the studied compounds.