Anions in aqueous precipitation - Determination of Anions in Natural and Treated Waters - page 438

A computer controlled multichannel continuous flow analysis system has been applied to
the measurement of phosphate (and nitrite, nitrate, chloride and sulphate) in rainwater
[22,23].
The application of this technique is also discussed under multianion analysis in
sections 5.1.14.4 and 14.4.2.1.

5.1.10.3 Gas chromatography

Faigle and Klockow [32] applied gas chromatography to the determination of traces of
phosphate (and nitrate and sulphate) in rainwater. The salts were freeze dried and
converted to the corresponding silver salts. These were then converted to n -butyl esters
with the aid of n -butyl iodide, the n -butyl esters being determined by

Table 5.4 Determination of phosphate in rainwater by ion chromatography

Type of water sample Co-determined onions Ref

Cl, F, Br, NO 2 , BrO 2

Rain [12]

NO 3 , SO 4

Rain [15]

Cl, NO 3 , SO 4 Rain [10]

Cl, NO 2 , NO 3 , SO 4 Rain [34]

Cl, I, Br, NO 2 , NO 3 , SO 4 , SO 3

Rain [6]

Source: Own files

direct injection into a gas chromatographic column comprising 3%OV-17 on Chromosorb
G.
The application of this technique is also discussed under multianion analysis in section
14.1.2.1.

5.1.10.4 Ion chromatography
Applications of ion chromatography to the determination of phosphate and other anions
in rainwater are summarised in Table 5.4. The application of this technique is also
discussed under multianion analysis in sections 5.1.14.3 and 12.4.1.

5.1.11 Sulphate
Sulphate is present in rain water at concentrations between 1 and 10mg L −1 and its
determination may provide valuable information on global pollution levels, atmospheric
circulation and geophysical phenomena. Also, the recent adoption of the catalytic
converter by the automobile industry has increased the interest in sulphate determinations
in rain water. The sulphate ion is considered to be the best indicator of change [35] in
aqueous precipitation composition due to anthropogenic activities.