Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 318

spectrometry and inductively coupled plasma mass spectrometry. The detection limit for
both elements by inductively coupled plasma atomic mass spectrometry was 0.06µg L −1
and by inductively coupled plasma atomic emission spectrometry the detection limits
were 1.2 and 0.4µg L −1 , respectively, for tungsten and molybdenum.
2.98.3 Preconcentration
The preconcentration of tungstate is discussed in section 15.1.13.
2.99 Tellurate
2.99.1 Spectrophotometric methods
A spectrophotometric method utilising tetramethyl thiourea as chromogenic reagent has
been described for the determination of tellurate in water [861].
2.100 Thiocyanate
2.100.1 Spectrophotometric methods
The spectrophotometric method for the determination of free cyanide in non saline waters
described by Nagashima and Ozawa [862] has also been applied to the determination of
thiocyanate.
A spectrophotometric method has been described for the determination of thiocyanate
(and simple and complex cyanides) in water in which the sample is reacted with acid
cuprous chloride and the released hydrogen cyanide absorbed in sodium hydroxide
solution. The alkali is then acidified and reacted with chloramine-T to produce cyanogen
chloride. A pyridine-pyrazolone reagent is added and the absorbance of the resulting blue
dye is evaluated at 620nm [863].
Thiocyanate, after complexation with mercury(II) and n -phenylbenzo hydroxamic acid,
has been determined spectrophotometrically [864].
2.100.2 Ion selective electrodes
Thiocyanate has been determined using a liquid membrane electrode [865].
2.100.3 Ion chromatography
The application of this technique is discussed under multianion analysis in section 12.2.5.
2.100.4 High performance liquid chromatography
Stetzenbach and Thompson [138] employed high performance liquid chromatography on
anion exchange columns to determine thiocyanate in admixture with chloride, bromide,