Appljcation of the thermal lens effectfor determination of iodide

A new method for the determination of trace amounts of iedide has been developed by using thethermal lens effect. The ion - pair complex formed from iedide with ethyl violet was measured using a singlebeam thermal lens experiment with a He - Ne laser as a light source. The sensitivity of the methed for determining iodide is 102 times higher than that of conventional spectrophotometry using the same colorimetric reaction. The detection limit of iodide is 50 pg. The method proposed has been applied to the determination of iodide at ppb levels in natural waters.