Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 91

[24,25].
The application of this technique is also discussed under multianion analysis in
sections 12.2.1 and 12.2.5.

2.8.5 Combustion method
Harmsen et al. [26] have described a rapid method for the determination of bicarbonate in
ground water and surface water. Using the inorganic channel of the Beckmann total
organic carbon analyser these workers determined the TOC content of a 2.0µL water
sample. Since the total inorganic carbon is dependent on the pH of the water, use of a
determined pH value allows determination of the total bicarbonate based on the
equilibrium equations of carbonic acid in water. Calculation in terms of mg L −1 is also
possible. These workers tabulate the percentages of carbon dioxide, bicarbonate ion and
carbonate ion and total organic carbon in water at 20°C as a function of pH over the
range pH 7.0 to 8.0 at 0.1 pH unit intervals. The method is rapid (2-3 min) and has an
accuracy of better than 2%, is insensitive to other weak acids and requires only small
sample volumes.

Table 2.1 Comparison of results obtained by the FIA-method, the electrometric method
and the automated segmented bromecresol geren method*

Sample Automated segmented
method
(HCO 3 − ] in mg L −1

Electrometric
method
[HCO − ] in mg L −1

FIA-method
[HCO 3 -1 ] in
mg L −1

Coefficient of
variation

1 226 268 248 0.99

2 485 546 532 0.46

3 266 298 305 0.98

4 266 306 313 0.56

5 213 232 236 0.71

6 250 276 288 0.66

7 120 142 135 0.98

8 160 259 287 0.48

9 267 291 324 0.31

10 480 317 332 0.56

11 107 120 110 0.26

12 117 123 110 0.27

13 119 123 112 0.24

14 120 125 113 0.31

15 113 109 110 0.42