Anions in trade effluents - Determination of Anions in Natural and Treated Waters - page 594

10.14 Polythionate
10.14.1 Titration method
The application of this technique is discussed under multianion analysis in section
14.3.2.1.
10.14.2 High performance liquid chromatography
The application of this technique is discussed under multianion analysis in section
13.1.4.1.
10.15 Selenate and selenite
10.15.1 Spectrofluorometry
A fluorometric procedure based on the use of 2,3-diaminonaphthalene has been used to
determine µg amounts of total selenate and selenite in industrial wastes then desorbed
using an acetonitrile gradient [41]. The eluate was monitored with an ultraviolet variable
wavelength detector.
10.15.2 Polarography
AC polarography and differential pulse polarography [42] and anodic stripping
voltammetry [43] have been used to determine selenium.
Batley [44] has given details of a procedure for determination of tetravalent selenium
in effluents, in the concentration range 2-100µg L −1 by using the sensitive adsorption
controlled peak obtained by differential pulse polarography in dilute acid solution. Heavy
metals which could interfere were removed on Chelex 100 resin. Hexavalent selenium
could be determined by the same method after photolytic reduction in the absence of
oxygen. For selenium concentrations below 2µg L −1 preconcentration by anion exchange
was necessary.
10.15.3 X-ray fluorescence spectrometry
Robberecht and Agemian [45] determined µg L −1 levels of total dissolved selenium and
selenite in natural waters by X-ray fluorescence spectrometry. Detection limits for
tetravalent selenium and total selenium are 50ng L −1 and 60ng L −1 .