Simultaneous determination of chlorine, bromine, and iodine in organic materials

A simple method is described for the simultaneous determination of chlorine, bromine, and iodine when present together in an organic material. The sample is combusted in a closed flask containing hydrazine sulfate, and contents transferred quantitatively to a volumetric flask. One aliquot is titrated directly for iodide content. Another equal aliquot is trated with acidic K2Cr2O7 and boiled to remove I2; the remaining contents are then titrated for chloride and bromide. An accuracy of +-0.33% was obtained for Cl, +-0.39% for Br, and +-0.26% for I. Binary mixtures can be sequantially titrated without pretreatment