Voltammetric Determination of Ecotoxic Nitro Compounds Using Polished Silver Amalgam Composite Electrode
Charles University in Prague, Faculty of Science, Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry, Prague
Voltammetric behavior of biologically active 5-nitro¬benzimidazole (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 l1 (DCV) and 2-100 μmol l1 (DPV), with the limits of quantification (LQ) ? 0.1 and 1 μmol l1 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 LQ ? 0.6 and 2 μmol l1, respectively.
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