A sensitive colorimetric method for the micro determination of iodine in marine water

More than 70% of the earth surface is covered by water bodies. Marine pollu tion is associated with the discharge of oils, petroleum products, sewage a gricultural wastes, pesticides, heavy metals, waste substances and dumping of radioactive waters in sea. This in turn results in hazards to human heal th, hindrance to aquatic organisms and impairment of quality for use of sea water. Sea water is reported to contain iodine but the concentration varie s according to the location and depth. Here a simple and sensitive method i s described for the determination of iodine using leucocrystal violet as a reagent in different samples of sea water. The method is based on the oxida tion of iodine to iodate with bromine water and the liberation of free iodi ne from the iodate by addition of potassium iodide in acedic medium. This i odine selectively oxidises leucocrystal violet to form the crystal violet d ye. Beer's law is obeyed over the concentration range of 0.04-0.36 ppm of i odine at lambda(max) 592 nm. The dye was further extracted in chloroform. T he extracting system obeys Beer's law in the range of 0.008-0.08 ppm at lam bda(max) 588 nm. (C) 1999 Elsevier Science B.V. All rights reserved.