Flow-injection method for the determination of iodide/iodine using Ru(bpy)(3)(3+)-NADH chemiluminescence detection.

A two-channel flow-injection (FI) method is reported for the determination of iodide and iodine by its enhancement effect on the Ru(bpy)(3)(3+)-NADH chemiluminescence (CL) system. The limit of detection (3 s of blank) was 1.0 x 10(-9) mol/L iodide/iodine, with a sample throughput of 60/h. The calibration graphs over the range 1.0-50 x 10(-8) mol/L gave correlation coefficients of 0.9994 and 0.999 (n = 5) with relative standard deviations (RSD; n = 4) of 1.0-2.5%, respectively. The effects of interfering cations, anions and some organic compounds were also studied. The method was applied to iodized salts and pharmaceutical samples and the results obtained were in good agreement with the value quoted. The CL method developed was compared with spectrophotometric method.