ABSTRACT
Differential pulse polarographic [DPP] and two spectrophotometric methods have been utilized for the quantitation of low levels of iodide [I-] in nine water samples collected from various stages of treatment for Riyadh city municipality water. The [DPP] method involves the conversion of I- into iodate [IO[-][3]] in alkaline medium and the consequent measurement of the peak current [Ip] in the voltage range -0.9 to -1.50 v. the electrode assembly employed consisted of the dropping mercury electrode [DME] as a working electrode; platinum as auxiliary and Ag/AgCI as reference electrodes. The spectrophotometric methods were based on reacting I with hydrogen peroxide [H2 O2] in acid medium to liberate I2 whose absorbance [A] was measured at [i] 352 nm [i.e. A[352]] and [ii] as iodo-starch complex at 602 nm [i.e. A[602]]. The limits of detection, based on signal-to-noise ratio of 3:1 were 0.035,3 and 5ppm for the DPP A[352] and A[602] methods respectively. Of the three methods investigated the DPP method proved to be superior in terms of sensitivity selectivity and applicability