Anions in aqueous precipitation - Determination of Anions in Natural and Treated Waters - page 429

on a paper tissue to remove the grey tarnish and then rinsing with deionised water. An
applied potential of 0.10V and a detector output range of 100nA V −1 were used.
A Technicon autosampler IV automatically delivered the sample to the ion
chromatograph and a Spectra Physics SP-4100 integrator measured the peak heights.
All reagent solutions prepared in deionised water. Use reagent grade sodium bromide
for the preparation of standards. The eluent mixture, consists of 0.003mol L −1 sodium
bicarbonate and 0.002mol L −1 sodium carbonate. The precolumn mix is Dionex 4×50mm
fast run anion and the separator column is 4×250mm.
The eluent is allowed to flow for approximately 30min to reach equilibrium. It takes
about 10min to complete the chromatogram using a 200µL sample loop. The retention
time of bromide was 5.4min. Use two calibration graphs, one for bromide concentration
of 0.10-1.0mg L −1 (with a 10V input) using a quadratic fit, and another for bromide
concentrations of 0.01-0.10mg L −1 (with a 1V input) using single point calibration with
intercept of zero. A reference water sample is used in every twentieth position of the tray.
To determine recoveries, known concentrations of bromide were added to several non
saline water samples; recoveries ranged from 97 to 110%. Typical results are given in
Table 5.1.
The application of ion chromatography is also discussed under multianion analysis in
sections 5.1.14.3, 12.4.1 and 12.4.2.

5.1.2.7 High performance liquid chromatography

The application of this technique is discussed under multianion analysis in section
13.1.3.1.

5.1.2.8 Ion exchange chromatography

The application of this technique is discussed under multianion analysis in section
13.3.2.1.

Table 5.1 Recovery of bromide in filtered water samples.

Sample No. Concentration (mg L −1 )
Chloride

Bromide Bromide added Bromide found Recovery (%)

1 31 0.59 0.5 1.13 108

2 263 0.46 0.5 1.03 108

3 63 0.33 0.3 0.65 107

4 56 0.30 0.3 0.61 103

5 2.28 0.22 0.3 0.51 97

6 5.95 0.040 0.05 0.089 98

7 4.59 0.037 0.05 0.086 98