Anions in potable waters - Determination of Anions in Natural and Treated Waters - page 516

Fig. 7.13 Layout of a continuous flow analysis system for determination of
sulphate
Source: Reproduced with permission from the Royal Society of
Chemistry [82]
produce a blue complex with absorption maximum at 620µm. Sulphate precipitated out
of the barium sulphate complex resulting in a loss of coloration which was measured
photometrically.
The methyl thymol blue flow injection method discussed in section 5.1.11.3 has also
been applied to the determination of sulphate in potable waters.
7.25.5 Atomic absorption spectrometry
Montiel [84] reacted sulphate in a buffered medium with excess standard barium
chloride. Unreacted barium was then determined by atomic absorption spectrometry at
553.55µm and the concentration of sulphate in the sample calculated. Errors due to the
presence of alkali and alkalineearth metals are corrected for by the incorporation of
calcium in the standard solution and by the presence of sodium in the buffer solution.
Siemer et al. [85] determined sulphate in potable waters by non-resonance line furnace
atomic absorption spectroscopy. Direct sulphur determination is not routinely performed
by flame or non-flame atomic absorption because of difficulties associated with the use
of the farultraviolet resonance lines of that element. Therefore, efforts were