Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 135

2.17.7 Column coupling capillary isotachophoresis
This technique offers very similar advantges to ion chromatography in the determination
of anions in water, namely multiple analysis, little or no sample pretreatment, speed,
sensitivity and automation. Very similar advantages are offered by capillary
isotachophoresis. Bocek et al. [189] determined chloride (and sulphate) in mineral waters
by this technique and Zelinski et al. [190] applied the technique to the determination of
0.02-0.1 mg L −1 quantities of chloride, fluoride, nitrate, sulphate, nitrite and phosphate in
river water.
The application of this technique is also discussed under multianion analysis in section
14.6.1.1.

Table 2.9 Results of determinations in potable water with the flow-through system in
comparison with reference methods (mg L −1 )

Sample Chloride Fluoride

Flow-through
system

Titration with
Ag

% Flow-through

system

Potentiometric with
TISAB

1 115.7 112.8 +2.6 0.178 0.174 +2.2

2 108.6 109.0 −0.4 0.166 0.166 0

3 119.2 118.6 +0.5 0.198 0.199 −0.5

4 119.8 119.5 +0.2 0.197 0.209 −5.9

5 66.1 72.4 −8.7 0.169 0.174 −2.9

Source: Reproduced with permission from the American Chemical Society [192]

2.17.8 Ion selective electrodes

Zeinalova and Senyavin [191] examined conditions for the potentiometric determination
of chloride in non saline water using an ion selective electrode. A pH range of 1-12 is
suitable for the determination of chloride. Macro- and microcomponents of non saline
water did not interfere with determining chlorides.
Trojanowicz and Lewardowski [192] have described a multiple potentiometric system
for the continuous determination of chloride, fluoride, nitrate and ammonia in non saline
waters. They describe a flowthrough system for the simultaneous determination of
chloride (30-150mg L −1 ), fluoride (0.08-0.4mg L −1 ), nitrate (5-20mg L −1 ) and ammonia
(0.05-0.5mg L −1 ). Solid state chloride and fluoride electrodes, a PVC membrane nitrate
electrode and a gas-sensing Orion 95-10 ammonia electrode were employed, the air-
segmented sample stream being mixed with appropriate buffering solutions before
entering the measuring cell. During continuous operation, calibration twice daily was
necessary to eliminate the effects of potential drift; best results were obtained when the
chloride-nitrate ratio in the calibrating solution was similar to that in the non saline water