Chemistry Reference
In-Depth Information
sample bottles and apparatus. Ramachandran and Gupta [6] performed studies on the
effects of different reducing agents on silicate determination by the molybdenum blue
method. Best results were obtained using ascorbic acid and antimony. The antimony did
not participate in the complex but enhanced its absorbance. The recommended procedure
is described. It was relatively rapid and sensitive. Beer's law was obeyed for silicate
concentrations of 20-1000µg L−1.
Pilipenko
et al.
[9] compared Spectrophotometric and chemiluminescent methods of
determining silicate in deionised water. They studied different reducing agents in the
molybdenum blue Spectrophotometric method, namely tungstosilicic acid, stannous
chloride, 1-amino-2-naphtholsulphonic acid and mixtures of metal and sodium sulphite.
They also studied the extraction of the blue tungstosilicic acid complex by isobutanol and
the formation of complexes of tungstosilicic acid with crystal violet and methylene blue.
The chemiluminescent method was based on the oxidation of luminol by molybdosilicic
acid in alkaline medium. These workers concluded that the best method, from the points
of view of detection limit, reproducibility simplicity and rapidity, was one based on the
reduction of molybdosilicic acid by 1-amino-2-naphthol-4-sulphonic acid.
11.2.5
Sulphate
11.2.5.1
Ion chromatography
The application of this technique is discussed under multianion analysis in sections
12.10.1 and 12.10.2.
11.2.6
Sulphite
11.2.6.1
Ion chromatography
Stevens and Turkelson [18] have described a procedure for the determination of down to
1mg L
−1
of sulphite in boiler blow down water.
11.3
Nuclear reactor cooling waters
11.3.1
Iodide
11.3.1.1
Titration method
Erdey and Kozmutza [19] used xenon difluoride as a reagent for the determination of mg
L
−1
quantities of iodide and iodine in nuclear reactor cooling waters. The test solution is
made IN in sulphuric acid and excess solid xenon difluoride added to convert iodide to
periodate which is then determined by standard iodometric procedures.
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