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 ma de 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 disso lved galvanostatically by applying a current of between - 50 and - 100 0 mu A while monitoring the potential of the working electrode. The me asured potential values were mapped into the memory of a computer, ena bling the dt/dE versus E relationship and the corresponding chronopote ntiometric transition times to be obtained directly. The analyte conce ntration was directly calculated from this value by making use of Fara day's law. The flow rate, deposition potential, pH and dissolution cur rent were optimized. The influence of Pb2+, Fe2+, Fe3+, surfactants, E DTA and humic acids on the analytical signal was studied. The method e laborated was used for analyses of water samples.