Anions in aqueous precipitation - Determination of Anions in Natural and Treated Waters - page 440

chloride, sodium bicarbonate, ammonium chloride, calcium nitrate and ferric nitrate)
(Table 5.6).
Reijnders et al. [37] concluded that segmented continuous flow analysis and flow
through titrimetry are suitable methods for the determination of sulphate in real samples.
Results of (segmented) flow injection analysis

Table 5.6 Comparison of interferences with respect to the examined methods

Found µmol L −1 sulphate

Sulphate
given
µmol L −1

Interference Cont flow

photometry;
thorin

Cont flow
photometry;
DMSA (III)

Flow-injection
photometry;
DMSA (III)

Cont. flow
titrimetry;
DMSA (III)

0.00 1 3 <1.4 <2.6 <5

0.00 2 140 3 7 <5

0.00 3 270 8 14 8

50.0 1 51 51 50 50

50.0 2 190 45 50 51

50.0 3 300 34 48 53

100.0 1 100 101 100 100

100.0 2 240 95 96 104

100.0 3 350 77 90 106

Key to interference:
1 No interference
2 Sulphate and interferences as specified in a 3 in a 1:1 dilution
3 Sulphate and 0.02mol L −1 NaCl, 0.0015mol L −1 KCl, 0.01 mol L −1 NaHCO 3 , 0.005mol L −1
NH 4 Cl, 0.0002mol L −1 Fe(NO 3 ) 3 , 0.01 mol L −1 Ca(NO 3 ) 2
Source: Reproduced with permission from Springer Verlag [37]

and flow through titrimetry are less affected by interfering ions. The dimethyl-sulphonazo
(III) chemical system is superior to the system with thorin.
The application of this technique is discussed under multianion analysis in section
14.5.1.1.
Hara et al. [38] have described a continuous flow determination of sulphate in rain
water using a lead selective electrode.

5.1.11.3 Flow injection analysis

Reijnders et al. [37] compared results obtained by the continuous flow method with those
obtained using a continuous flow apparatus and a flow through titrimeter. In each case
dimethylsulphonazo(III) was used as a chromogenic reagent. Results obtained by these