SYNERGETIC CATALYTIC EFFECT OF MOLYBDATE AND TUNGSTATE ON THE HYDROGEN-PEROXIDE IODIDE SYSTEM AND ITS ANALYTICAL APPLICATIONS

The synergetic catalytic effect of molybdate and tungstate on the hydr ogen peroxide-iodide system has been studied by using the I-3(-)-starc h complex as the indicator with a stopped flow injection technique. Th e degree of the synergetic effect was expressed by the proposed concep t of a synergetic catalytic coefficient, D. The deviations from additi vity of absorbance outside certain concentration ranges in the previou s procedures could be compensated for by introducing the synergetic co efficient in the simultaneous measurement of a binary mixture with the stopped now injection method. The linear concentration ranges could t hus be extended by compensation, to 0-1.1 mu g/ml for Mo and 0-2.0 mu g/ml for W, in comparison to 0-0.6 mu g/ml for Mo and 0-0.8 mu g/ml fo r W as obtained with the procedure in which no compensation was applie d, and the sensitivities also have been improved. The molybdenum and t ungsten content in steel and simulated samples was determined, and the recoveries and relative standard deviations were 97.3-102.8% and 2.1- 2.9%, respectively, for molybdenum, and 96.5-102.1% and 2.3-3.4% for t ungsten.