INDICATOR TUBES FOR THE DETERMINATION OF REDUCING AGENTS IN SOLUTION

A method using indicator tubes is developed for the determination of r educing agents in solutions. The reactions of ion associates formed by thiazine dyes (Methylene Blue and Toluidine Blue) and triiodide ions with reducing agents (S2O32-, SO32-, diethyl dithiocarbamate, ethyl xa nthate, and ascorbic acid) in solution are studied. Indicator tubes ar e proposed for determining total reducing agents and ascorbic acid. Th e dependence of the length of colored zones on the tube diameter, the flow rate of the solution, and the concentration of the Triton X-100 s urfactant was examined. The tubes proposed are essentially superior to commercial test kits in reproducibility and compare well with them in sensitivity and analytical range. The tubes are recommended for the d etermination of total reducing agents in waste water and of ascorbic a cid in fruit juices.