Iodine in mineral waters: A comparison of results from two analytical techniques

Abstract

Abstract.A comparative study of the determination of iodine in mineral waters is presented. Iodine was first determined by a standard titrimetric method and the results obtained were compared with those obtained by the faster and more sensitive radiochemical neutron activation method. For a series of waters, the results obtained by the two techniques were in fair agreement for the higher concentration levels of iodine, but for very low iodine levels the titrimetric method was insufficiently sensitive. The RNAA procedure was checked by standard addition experiments, and shown to be also valid when iodine was present as iodate.Key words: iodine, mineral waters, titrimetry, radiochemical neutron activation analysis.Underground waters with a higher content of dissolved mineral substances or compounds (> 1 g/l) and gases (> 250 mg/1) and with natural biological purity are classified as mineral waters [1,2]. The utilization of mineral waters for drinking and medico-balneological purposes necessitates reliable quantitative data on their essential micro-constituents, including iodine.Correlations between endemic goitre and iodine deficiency date from the last century. Clinical research on this phenomenon in different parts of the world also shows a good correlation between goitre and the iodine content of drinking waters. The frequency of its incidence is higher in areas where the iodine content in drinking waters is less than 3 #g/l, and iodination of the water considerably reduces this effect /-3, 4]. In comparison with normal ground and surface waters, mineral waters are usually enriched with iodine, though this can depend on the geological structure of

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

“…It has been reported that neutron irradiation of aqueous samples with iodine in polyethylene vials resulted in a significant loss of activity of iodine on the walls (up to 60−70% of total iodine), which can be avoided by addition of ammonia or ethanol, − but a reverse result has also been reported for the analysis of organic bound iodine and mineral water . Thus, we tested the adsorption of iodine in deionized water and seawater on the wall of a polyethylene vial during neutron irradiation by measuring the iodine content on the polyethylene vial after irradiation.…”

“…In seawater, the concentrations of sodium, chlorine, and bromine are quite high, and it is difficult to directly determine iodine by instrumental NAA. Thus, ion-exchange preconcentration 30 and postirradiation radiochemical NAA 32 (RNAA) have been used for the determination of iodine in seawater. In this work, the postirradiation NAA was chosen for the determination of iodine content in natural seawater and the different separated fractions.…”

“…It has been reported that neutron irradiation of aqueous samples with iodine in polyethylene vials resulted in a significant loss of activity of iodine on the walls (up to 60-70% of total iodine), which can be avoided by addition of ammonia or ethanol, [33][34][35] a reverse result has also been reported for the analysis of organic bound iodine 36 and mineral water. 32 Thus, we tested the adsorption of iodine in deionized water and seawater on the wall of a polyethylene vial during neutron irradiation by measuring the iodine content on the polyethylene vial after irradiation. The results (Table 2) indicate that about 1% of iodine was adsorbed onto the polyethylene walls from deionized solution of iodine during irradiation, and no remarkable difference was found between the results determined with and without the addition of NH 4 OH (final NH 4 + concentration of 0.7 mol/L).…”

“…Neutron activation analysis (NAA) is a sensitive method for the determination of iodine. It has been used extensively for the determination of total iodine in biological samples, − air particles, and water (rain, freshwater, mineral water, and seawater) samples, − I - , IO 3 - , and organic iodine in seaweed, I - and IO 3 - in rainwater, and organic, inorganic, and particulate iodine in air particles . However, NAA of seawater for different chemical species of iodine, such as IO 3 - and organic iodine, has not been reported.…”

A study of iodine loss during the preparation and analysis of samples using 131I tracer and neutron activation analysis

“…However, few papers describing detailed studies of iodine stability in the preparation and analysis process are available. Belling et al 5,6 studied the recovery of iodine in dry, alkali ash and acid digestion, Zaichick and Zaichick 7 and Ishikawa et al 8 studied the loss of iodine in lyophilisation of biological samples and Heurtebise and Ross 9 and Byrne et al 10,11 investigated the loss of iodine in neutron irradiation. However, in all these papers, the analyte investigated was total iodine in the samples, and no study of the stability of different chemical species of iodine in the sample preparation process was reported.…”