An improved method for the flow-injection determination of iodine using the luminol chemiluminescence reaction in a reversed micellar medium of cetyltrimethylammonium chloride in 1-hexanol-cyclohexane.

To eliminate the use of chlorinated hydrocarbons, we have improved the method for the flow-injection (FI) determination of iodine based on the chemiluminescence reaction of iodine with luminol in a chloroform-free reversed micellar medium of the surfactant cetyltrimethylammonium chloride (CTAC) using a mixture of 1-hexanol-cyclohexane as a bulk solvent. The FI procedure used simply involves the mixing of an iodine solution in cyclohexane with the chemiluminescent reagent solution of luminol in the reversed micellar medium of CTAC in 0.38 M 1-hexanol in cyclohexane/water (buffered with sodium carbonate). The optimum conditions for the iodine determination were evaluated and a detection limit (DL) of 0.05 ng cm(-3) iodine was achieved. The calibration graph obtained was linear with a dynamic range from the DL to 10 ng cm(-3) iodine. The relative standard deviations (n=5) observed at all concentrations within the linear range were less than 2.5%. The improved FI method is rapid and equally sensitive like the original one and was found to be suitable for the determination of trace iodine.