Anions in aqueous precipitation - Determination of Anions in Natural and Treated Waters - page 428

5.1.2.2 Continuous flow analysis
The application of this technique is discussed under multianion analysis in section
5.1.14.1.

5.1.2.3 Flow injection analysis
The application of this technique is discussed under multianion analysis in section
14.4.2.1.

5.1.2.4 X-ray fluorescence spectroscopy
The application of this technique is discussed under multianion analysis in section
14.7.1.1.

5.1.2.5 Neutron activation analysis
Slanina et al. [2] claim that a detection limit of 1µg L −1 can be achieved in the
determination of bromide in rainwaters by neutron activation analysis. Typical accuracy
was 5% relative using a 1ml sample.

5.1.2.6 Ion chromatography
Ion chromatography using an amperometric detector has been used to determine down to
10µg L −1 bromide in rainwater and ground waters [3]. The equipment features an
automated ion chromatograph, including a programme controller, an automatic sampler,
an integrator and an amperometric detector. A fixed potential is applied to the cell. Any
electroactive species having an oxidation-reduction potential near the applied potential
will generate a current that is directly proportional to the concentration of the
electroactive species.
The detection limits for bromide is 0.01mg L −1 and the relative standard deviation is
less than 5% for bromide concentrations between 0.05 and 0.5mg L −1 . Chloride interferes
if the chloride to bromide ratio is greater than 1000:1 for a range of 0.01-0. 1mg L −1
bromide; similarly, chloride interferes in the 0.1-1.0mg L −1 range if the ratio is greater
than 5000:1. In the latter case, a maximum of 2000mg L − 1 chloride can be tolerated.

Recoveries of bromide ranged from 97 to 110%.
This analysis is performed using a Dionex Model 12 ion chromatograph with 200µL
sample loop, an eluent flow rate of 2.3ml min −1 (30% of full capacity) and a sample
pump flow rate of 3.8ml min −1 (50% of full capacity). Pulse damper is installed just
before the injection valve to reduce flow pulsation. A Dionex amperometric detector
consisting of cell and potentiostat. The cell contains a silver working electrode, a
platinum counter electrode and an Ag/AgCl reference electrode. This cell is installed
between separator and suppressor columns. The working silver electrode should be
cleaned monthly by polishing the surface with a small amount of an abrasive toothpaste