Chemistry Reference
In-Depth Information
Cranston and Murray [235] have reviewed methods for the determination of chromium
species in non saline waters.
2.20
Cis aconitate
2.20.1
Ion chromatography
The application of this technique is discussed under multianion analysis in section 12.2.4.
2.21
Citrate
2.21.1
Spectrofluorometric method
Bishop [236] has proposed spectrofluorometric tests for the presence of citrate in water.
2.21.2
Ion chromatography
The application of this technique is discussed under multianion analysis in section 12.2.4.
2.21.3
Ion exclusion chromatography
The application of this technique is discussed under multianion analysis in section
13.2.1.4.
2.22
Condensed phosphates
Condensed phosphate is a generic title for all phosphates which are formed by the
removal of one or more water molecules from orthophosphoric acid, which may be
represented as 3H
2
O·P
2
O
5
. These include metaphosphoric acid (H
2
O·P
2
O
5
ie HPO
3
),
pyrophosphoric acid (2H
2
O·P
2
O
5
ie H
4
P
2
O
7
), ultraphosphoric acid (general formula
mH
2
O·P
2
O
5
where 0
≤
m
≤
1), and polyphosphoric acid (general formula mH
3
PO
4
- (m-
1) H
2
O where 1
≤
m
≤∞
). The most common condensed phosphates are pyrophosphate
and tripolyphosphate which have dissociable protons and behave as typical polyprotic
acids. Both exist in three forms.
P
yrophosphoric acid is represented as H
4
P
2
O
7
(2H
2
OP
2
O
5
). The three forms of
pyrophosphate are:
H
3
P
2
O
7
1−
, H
2
P
2
O
7
2−
and HP
2
O
7
3−
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