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Voltammetric Determination of Quinoxaline at a Mercury Meniscus Modified Silver Solid Amalgam Electrode
Kotasová, Marcela ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
The aim of this Bachelor Thesis was to develop sensitive, inexpensive, and less time-consuming voltammetric methods for the determination of quinoxaline. For this purpose, DC voltammetry (DCV) and differential pulse voltammetry (DPV) at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) were used. The optimization consisted of finding a suitable medium and a suitable regeneration of the electrode surface. The optimal medium for the determination of quinoxaline was a solution of the Britton-Robinson buffer of pH 13,0, and it was also found that for both techniques, it is advisable to use regeneration potentials Ein = -100 mV a Efin = -1800 mV for the cleaning of the electrode surface. Concentration dependences were measured in the concentration range of 1.10-7 - 1.10-4 mol.L-1 of quinoxaline. Over all concentration ranges, the dependences were non-linear, however, it was possible to fit them with a high correlation using a polynomial function of the second order. The limits of quantification (LQ) reached were 8.2×10-7 mol.L-1 (DCV - evaluated the peak height), 3.9×10-7 mol.L-1 (DPV - evaluated the peak height), and 2.8×10-7 mol.L-1 (DPV - evaluated the peak area). The spectrophotometric determination of quinoxaline, which was performed for a comparison, provided two peaks with the...
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