Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 169

Magnesium-quinolin-8-ol system
Fluoride ions cause fluorescence quenching on the magnesium-quinolin-8-ol system. This
is used to measure air pollution with a fluoride analyser in which air is drawn past a
moving 35mm tape freshly impregnated with magnesium-quinolin-8-ol [318,319].
Variations in the fluorescence are recorded continuously for the assay of fluoride. Ivie
[320] and Thompson et al. [321] also designed a simplified fluoride analyser with the
same system.

2.31.3 Flow injection analysis
Manzoori and Miyazaki [322] applied indirectly coupled plasma atomic emission
spectrometry to the determination of 0.03µg L −1 of fluoride in solvent extracts of non
saline water.
Gehlhausen and Carnahan [323] have described a method for the determination of
aqueous fluoride by flow injection analysis with a helium microwave-induced plasma.
This system operates at 500W and utilises a modified TM 010 resonator cavity with a
demountable plasma torch. Both direct nebulisation and flow injection analysis in
conjunction with ultrasonic nebulisation were investigated. Flow injection analysis was
found to be the most reliable method because extended nebulisation of aqueous fluoride
was found to cause memory effects. Detection limits for aqueous fluoride of 35 and 4ppm
were observed for flow injection analysis and direct ultrasonic nebulisation respectively.
The interference effects of pH and selected elements were also studied.

2.31.4 Inductively coupled plasma atomic emission spectrometry
To preconcentrate fluoride, Miyazaki and Brancho [324] converted fluoride into the
ternary lanthanum-alizarin complexone fluoride and extracted it into hexanol containing
N,N -diethylaniline. The extract was analysed directly by inductively coupled plasma
atomic emission spectrometry for the determination of fluoride. Measurement of the
lanthanum(II) 333.75nm, emission line and comparison with a calibration graph enabled
fluoride concentrations as low as 0.59µg L −1 to be determined in Japanese river water
(polluted and unpolluted), coastal seawater, and potable water samples. The relative
standard deviation was 2.6% for 40µg L −1 of fluoride. Alkali and alkaline earths do not

interfere with this method.

2.31.5 Column coupling capillary isotachophoresis
This technique offers very similar advantages to ion chromatography in the determination
of anions, namely multiple ion analysis, ie little or no sample pretreatment, speed,
sensitivity and automation. Very similar advantages are offered by capillary
isotachophoresis. Zelinski et al. [325] applied the technique to the determination of 0.02-
0.1mg L −1 quantities of fluoride, chloride, 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.