Determination of Chemical Species of Iodine in Seawater by Radiochemical Neutron Activation Analysis Combined with Ion-Exchange Preseparation

Abstract

A method for the determination of iodide, iodate, organic iodine, and total iodine in seawater was developed. The behaviors of loading, washing, and eluting of iodide, iodate, and organic iodine in a strongly basic anion-exchange column (AG1-×4, chlorine form) were studied by 131I tracer. Iodide was separated from other iodine species and other ions by directly passing filtered natural seawater through an anion-exchange column, washing with deionized water and 0.5 mol/L KNO3 solution, and eluting with 2.0 mol/L KNO3. Organic iodine was separated by passing seawater through an ion-exchange column after iodate had been converted to iodide by KHSO3 and collecting effluent during loading and washing with deionized water. The iodine content was determined by neutron activation analysis with postirradiation separation using CCl4 extraction. Studies of the effect of chlorine, bromine, and iodine concentrations on the extraction separation show that the recovery of iodine decreases with increasing Br- and Cl- concentrations and decreasing I- concentration. Under the experimental conditions, iodine in seawater was quantitatively recovered, and a 0.2 μg/L detection limit for iodine was obtained. Concentrations of total iodine, I-, IO3 -, and organic iodine in seawater collected from Roskilde Fjord, Denmark, were determined.

Measurement of 129I Radioactivity in Groundwater of Radioactive Waste Disposal Site

“…The mechanism of conversion among iodine species is still not clear because of the difficulties associated with distinguishing the origin of newly produced and converted iodine species. 3,4,7) It is possible that the chloride anion competes with iodide anion in the separation step. The groundwater sampled in the disposal site was analyzed.…”

“…The concentrations of 129 I and 127 I were determined from those of 130 I and 126 I. 2,6,7) AMS was also used to measure the 129 I and 127 I radioactivity after pretreatment. 4,5) Measurement of 129 I can be carried out by an X-ray detector and liquid scintillation counter.…”

“…The iodine was separated by CCl 4 extraction or anion exchange. 2,3,4,7,9) These methods have been used for the seperation of 129 I in the analysis using NAA or AMS. In this study, the oxidant and reductant were used for the fixation of iodine species in the water.…”

Kinetic Spectrophotometric Determination of Trace Amounts of Iodide in Food samples

“…Several sensitive methods used for determination of trace amounts of iodide in various samples include inductively coupled plasma-atomic emission spectrometry (ICP-AES), 6,7 inductively coupled plasma-mass spectrometry (ICP-MS), 8,9 neutron activation analysis (NAA), 10,11 ion chromatography (IC), [12][13][14] molecular absorption spectrometry 15 and an optical redox sensor. 16 These methods are expensive and require preconcentration [6][7][8][9][10][11][12][13][14] and/or separation [10][11][12][13][14] of the samples or special instruments.…”

“…16 These methods are expensive and require preconcentration [6][7][8][9][10][11][12][13][14] and/or separation [10][11][12][13][14] of the samples or special instruments. [6][7][8][9][10][11]15,16 However, we need a simple, sensitive and selective method that does not require any excess process of foods in order to analyze a large number of samples.…”