DETERMINATION OF MANGANESE IN WATER SAMPLES BY GALVANOSTATIC STRIPPING CHRONOPOTENTIOMETRY IN A FLOW-THROUGH CELL

A dow-through electrochemical cell, with a porous working electrode made of crushed glassy carbon, was used for the complete electrochemical deposition of the Mn-II species from a flowing sample solution at + 1.2 V versus an Ag-AgCl reference electrode. The deposit was then dissolved galvanostatically by applying a current of between - 50 and - 1000 mu A while monitoring the potential of the working electrode. The measured potential values were mapped into the memory of a computer, enabling the dt/dE versus E relationship and the corresponding chronopotentiometric transition times to be obtained directly. The analyte concentration was directly calculated from this value by making use of Faraday's law. The flow rate, deposition potential, pH and dissolution current were optimized. The influence of Pb2+, Fe2+, Fe3+, surfactants, EDTA and humic acids on the analytical signal was studied. The method elaborated was used for analyses of water samples.