Chemistry Reference
In-Depth Information
8.2
Bromide
8.2.1
Ion chromatography
The application of this technique is discussed under multianion analysis in section 12.7.1.
Table 8.7
Typical results: 10 samples of coal mine waste water were analysed in
triplicate
Sample No
Result in
mg L
−1
Sample No
Result in
mg L
−1
1
3.21
6
2.64
2
2.89
7
2.57
3
2.79
8
3.01
4
1.86
9
2.56
5
2.85
10
3.43
Relative standard deviation for all samples is between 0.5 and 3% for three analyses.
Approximate time of analyses is 2.8min.
Source: Reproduced with permission from Orion Research Inc. [12]
8.3
Chloride
8.3.1
Titration method
Barrera and Martinez [11] compared two methods, the Mohr procedure based on
precipitation of silver chloride with a chromate indicator and the mercuric nitrate method
based on the formation of soluble, slightly ionised mercuric chloride, for the volumetric
determination of chlorides in waste waters. Results are in agreement. The mercuric nitrate
method is preferred because the end-point is sharper, a magnetic stirrer is not required,
the range of concentrations is 0-700mg L
−1
(against 5-300mg L
−1
) and it is less
expensive for both high and low chloride concentrations.
Workers at Orion Research Inc. [12] have described a method for the determination of
chloride in mine waste water using the KAP analysis technique of multiple known
addition. Although the samples could be measured by titration with silver nitrate, use of
the KAP technique offers some advantages; it is more reliable at low levels (at few mg
L
−1
) of chloride, especially when there may be interfering ions such as phosphate present,
which also react with silver; and the KAP technique can be used over a very wide range
of sample concentration, without the need to adjust the standard concentration (Table
8.7).
Search WWH ::
Custom Search