The synergistic inductive effect of iron(II) and antimony(III) upon the chromium(VI)-iodide kinetic reaction systems had been studied, and the concept of synergistic inductive coefficient was defined. The deviations from additivity of absorbance within certain concentration ranges in previous procedures can be compensated effectively, by introducing the synergistic coefficient into the simultaneous determination of a binary mixture with stopped flow-FIA method, and the linear concentration ranges have also been enlarged remarkably. Iron and antimony contents in wastewater, a simulated sample and a zinc standard had been determined, the results are satisfactory.

Key words: SPECTROPHOTOMETRY, STIBIUM, IRON, SYNERGISTIC EFFECT, SIMULTANEOUS DETERMINATIONS, FLOW INJECTION ANALYSIS, INDUCTIVE EFFECT, DICHROMIC ACID