A simple and sensitive spectrophotometric method for the determination of iodine in environmental samples

A simple and sensitive spectrophotometric method for the determination of iodine in various samples is described. The method is based on oxidation of iodide to iodate with bromine water and liberation of free iodine from iodate by addition of potassium iodide in acidic medium. The iodine is then reacted with leuco crystal violet and the crystal violet dye liberated shows maximum absorbance at 591 nm. Beer's law is obeyed over the concentration range from 0.04 to 0.36 mg l(-1) of iodine in a final solution volume of 25 ml. The molar absorptivity of the colour system is 5.6 x 10(5) l mol(-1) cm(-1). The method is free from the interference of other major toxicants. The analytical parameters have been optimized and the method has been applied to the determination of iodine in environmental samples i.e. tap water, sea water, soil, iodized salt and pharmaceuticals.