Spectrophotometric Determination of Periodate, Iodate and Bromate Mixtures Based on Their Reaction with Iodide

Abstract

IntroductionPeriodate, iodate and bromate are important oxidants which can oxidize many inorganic and organic compounds. These ions have been extensively used as ingredients for indicators in catalytic-kinetic analysis involving redox processes. Iodate and bromate have been reported to be toxic ions. 1,2 The major rout of enviromental exposure to these oxihalides is drinking water. Bromate is a by-product of bromide containing water ozonization. Iodide ions may be found in brakish water and, to a lesser extent, in freshwater, and may form iodate during ozonization. Therefore, their determinations are required for enviromental protection.Several methods have been reported for the determination of periodate, iodate and bromate in mixtures. These include the spectrophotometric determination of periodate-iodate mixtures, [4][5][6] spectrophotometric, 7-9 chromatographic 10,11 and polarographic 12 determination of iodate-bromate and periodatebromate mixtures. To the best of our knowledge, there is only one report concerning the determination of ternary mixture of periodate, iodate and bromate.Kavalenties 13 determined periodate, iodate and bromate mixtures by means of 3,4-dihydroxybenzaldehyde guanylhydrazone (3,4-DHGB). Periodate, iodate and bromate oxidized 3,4-DHGB in slightly acidic medium, in 0.1 M HClO4 medium and in 20% HClO4, respectively. The absorbance of the oxidized 3,4-DHGB was measured at 420 nm. Periodate, iodate and bromate could be determined in the ranges of 1 -30, 0.5 -16 and 0.4 -14 µg/ml, respectively.In this paper we describe a rapid, simple, precise and accurate method for the spectrophotometric determination of periodate, iodate and bromate ions in mixtures. The method is based on the reaction of periodate, iodate and bromate with iodide in acidic media at three different pH values. Experimental ApparatusA Shimadzu Model UV-265 UV-Visible recording spectrophotometer with 1-cm glass cells was used for absorbance measurements. ReagentsTriply distilled water and analytical-reagent grade chemicals were used.Standard solutions of periodate, iodate and bromate were prepared by dissolving an appropriate amount of sodium periodate, sodium iodate and potassium bromate (all from Merck) in water. A 0.15 M iodide solution was prepared by dissolving 5.625 g sodium iodide (Merck) in water and diluting to the mark in a 50-ml volumetric flask. Citrate buffer solutions (0.1 M) of pH 6 and 3.3 were prepared from sodium citrate, sodium hydroxide and hydrochloric acid solutions and 0.1 M glycine buffer solution of pH 1 was prepared from glycine and hydrochloric acid solutions. ProceduresThree runs were needed for each sample. In the first run, an aliquot of a solution containing 1.5 -17 µg of periodate, 1.0 -18 µg of iodate and 2.0 -120 µg of bromate was transferred into a 10 ml volumetric flask. Then, a 2 ml volume of a pH 6.0 buffer solution was added. The solution was diluted to ca. 9 ml with water and 1.0 ml of a 0.15 M iodide solution was added. A stopwatch was started just after the addition of the iodide s...

Thermal gelation and tissue adhesion of biomimetic hydrogels

“…Unentrapped NaIO 4 was removed from the liposome suspension by washing with iso-osmotic PBS (pH 6), centrifuging at 20 000 × g, and decanting the supernatant. This process was repeated a minimum of five times or until NaIO 4 could not be detected in the supernatant, using a standard spectrophotometric method [27]. CaCl 2 -entrapped liposomes (CCVs) used for control experiments were prepared by the reported method [26].…”

Sensitive Kinetic-Spectrophotometric Determination of Iodate in Iodized Table Salt Based on Its Accelerating Effect on the Reaction of Bromate with Chloride Ion in the Presence of Hydrazine

“…2 Several methods have been reported on the determination of iodate, such as gas chromatography-mass spectrometry, 3 ion chromatography, 4 chemiluminescence, 5 flow injection amperometry 6 and spectrophotometry. [7][8][9][10][11] Some reported spectrophotometric methods for the determination of iodate are based on its reaction with excess iodide to form triiodide. [7][8][9] In other spectrophotometric methods, iodate was determined after prior oxidation to periodate.…”

“…[7][8][9][10][11] Some reported spectrophotometric methods for the determination of iodate are based on its reaction with excess iodide to form triiodide. [7][8][9] In other spectrophotometric methods, iodate was determined after prior oxidation to periodate. 10,11 The ion-associate of periodate with a suitable ion pairing agent was then extracted into an organic solvent and determined by spectrophotometric methods.…”

Simultaneous kinetic spectrophotometric determination of Cu(II), Co(II) and Ni(II) using partial least squares (PLS) regression

“…A number of differential kinetic methods were developed for resolving mixtures of analytes with similar or identical spectra that could not be resolved by equilibrium-based methods [9][10][11][12][13][14][15][16][17]. The simultaneous kinetic determination of such analytes is usually based on the difference in their reaction rate constants.…”