Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 179

electrode in a solution at pH 9 [347,348]. No interference was caused by fluoride,
chloride, bromide or thiosulphate. Only low concentrations of sulphide and cyanide can
be tolerated.
Nakayama et al. [349] carried out automated determination of iodate in non saline
waters using a flow-through electrode system. Following oxidation to iodine, quantitative
concentration was obtained on a carbon wool electrode in a preconcentration cell.
Residual chloride and bromide ions were then removed by rinsing the preconcentration
cell with acetic acid. Iodine was eluted with reducing agent in a detection cell housing a
polished silver electrode and iodate determined after being reduced to iodide. Current
voltage curves obtained with the polished electrode are illustrated. The effect was studied
of various salts on the peak current obtained in the analysis of filtered seawater. A
detection limit of 5ng of iodine is claimed for this method.
2.49.6 High performance liquid chromatography
Salov et al. [115] determined iodate, chloride, iodide, chlorate and bromate in non saline
waters by high performance liquid chromatography with an inductively coupled argon
plasma mass spectrometric device.
The application of this technique is also discussed under multianion analysis in section
13.1.1.7.
2.49.7 Micelle exclusion ion chromatography
Okada [350] has used micelle exclusion chromatography to determine iodate in the
presence of other anions (iodide, bromide, nitrite and nitrate) in water. The method is
based on partition of the anions to a cationic micelle phase and shows different selectivity
from ion exchange chromatography.
This technique has been applied to the determination of iodate, nitrite, nitrate, bromide
and iodide in non saline waters [351].
2.49.8 Preconcentration
The preconcentration of iodate is discussed in section 15.1.5.
2.50 Iodide
2.50.1 Titration methods
The potentiometric titration procedure described by Kuttel et al. [117] for the
determination of chloride in non saline waters has also been applied to the determination
of iodide.
Bardin and Tolstousov [352] used a flow-type concentration cell with two silver-silver
iodide electrodes for the potentiometric determination of down to 3µg L − 1 of iodide in
non saline waters. At iodide concentrations of up to 0.6µM the variation in emf of the cell
is rectilinearly proportional to the concentration of iodide.