Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 319

iodide and nitrate in non saline water.
The application of this technique is also discussed under multianion analysis in
sections 13.1.1.2 and 13.1.1.4.
2.100.5 Micelle chromatography
The application of this technique is discussed under multianion analysis in section
13.5.1.3.
2.100.6 Gas chromatography
Nota et al. [866] have described a gas chromatographic headspace analysis technique for
the determination of 0.01-100mg L −1 thiocyanate (and cyanide) in coke oven effluents.
2.100.7 Miscellaneous
Gonzalez et al. [867] described the miscellar determination of mixtures of thiocyanate
and sulphite. The method is based on reaction with 5,5 ′ -dithiobis-(2-nitrobenzoic acid) in
aqueous cetyltrimethyl ammonium bromide miscelles. Down to 0.5-1.5×10 −4 mol L −1
concentrations of thiocyanate can be determined with a relative error of less than 5%.
Thieleman [868] attempted the separation of thiocyanate, cyanate and cyanide ions by
thin layer and paper chromatography. Thin layer chromatography was not successful but
these three ions were successfully separated by paper chromatography with the solvent
methanol:pyridine:dioxan (7:2:1) in 7-8h. Cyanide and cyanate were identified by means
of bromocresol purple and thiocyanate by 15% ferric chloride solution, as spray reagent.
Carbonate ions have the same R F value as cyanide and cyanate.
2.101 Thiosulphate
2.101.1 Titration methods
Thiosulphate (and sulphate) can be titrated potentiometrically with mercuric ions using a
sulphide ion selective electrode in 0.1N sodium hydroxide medium [853]. Sulphite can be
decomposed with formaldehyde and, consequently, thiosulphate can be titrated alone.
Polysulphide and sulphide can be converted to thiosulphate and titrated. Thiosulphates
can be determined in non saline waters by titration with mercury(II) solutions. Sulphides,
polysulphides and sulphites interfere in this procedure [663].
2.101.2 Flow injection analysis
The application of this technique is discussed under multianion analysis in section
14.4.1.1.