QUANTITATIVE IN-SITU DETERMINATION OF IRON IN A SODA-LIME-SILICA GLASS MELT WITH THE AID OF SQUARE-WAVE VOLTAMMETRY

Square-wave voltammetric measurements are fairly convenient to determi ne thermodynamic data and diffusion coefficients of polyvalent element s in glass melts. In principle, these methods also allow the quantitat ive in-situ determination of the total concentrations of polyvalent io ns. For the in-situ determination of small quantities, however, improv ements of the measuring and analyzing procedures were necessary. This was achieved by approximating background currents using polynoms and d escribing Faradaic currents using theoretically derived equations. Sim ulations using least square approximations then allow a much more deta iled analysis of the current potential curve. Further improvements wer e possible by preelectrolyzing the melt at negative potentials and the n shifting the potential to zero while recording the square-wave volta mmogram. Using both procedures, a quantitative determination of iron c oncentrations as low as 0.004 mol% Fe2O3 is possible.