Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 131

A further method [174] is based on the oxidation of chloride to free chlorine by
potassium permanganate solution. Chlorine is then swept out of the solution by a nitrogen
purge and determined by the o-toluidine Spectrophotometric method at a wavelength of
450nm.
Rossner and Schwedt [175] have described a Spectrophotometric method for the
determination of chloride in non saline water which is based on the FeII-Hg tripyridyl-s-
triazine system. This method is applicable in the 10µg L −1 to 10mg L −1 concentration
range. A modification of the technique based on continuous flow analysis has a detection
limit of 5µg L −1 .
McCurdy et al. [176] give details of a procedure developed for routine determination
of chloride in environmental groundwater samples using a Cobas Fara centrifugal
analysis; the procedure was based on the Spectrophotometric hexacyanoferrate method.
Ferric nitrate was a more sensitive donor of trivalent iron than ammonium ferric sulphate.
The method was tested on several reference mineral samples and the results were
compared with those obtained using a Technicon AAII continuous-flow analyser. The
procedure gave results that were both accurate and precise.
Yoshida et al. [177] stirred a chloride-containing sample with thiocyanate-loaded anion
exchange resin for 10min. The displaced thiocyanide reacted with iron(III) that was
added to the system to produce a red colour; measurement of the absorbance at 455nm
provided