2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P87 ThE FLuORIMETRIC DETERMINATION OF
ALuMINIuM, GALLIuM AND INDIuM wITh
8-hyDROxyQuINOLINE-5-SuLPhONIC ACID
IN AQuEOuS AND SubMICELLAR MEDIuM
ŠIMOn VOJTA and LUMíR SOMMER
Institute of Environmental Protection, Faculty of Chemistry,
Brno University of Technology, Purkyňova 118, 612 00 Brno,
Czech Republic,
halapaloosa@email.cz
Introduction
The complexing and analytical properties of 8-Hydroxyquinoline-5-sulphonic
acid (QSA) are similar to 8-Hydroxyquinoline
but the solubility of complexes in aqueous solutions
increases and no fluorescence of the reagent in the large
pH interval has been observed. The QSA was formerly used
as a fluorogenic reagent for a number of metal ions including
Mg 2+ , Zn 2+ , Cd 2+ , Ce 3+ and Al 3+ (ref. 1 ). The fluorimetry
of Gallium and Indium complexes in aqueous solutions was
only briefly mentioned.
The fluorescence of metal complexes with QSA can be
considerably enhanced in the presence of surfactants in submicellar
and micellar medium 2,3 . The fluorescence properties
of the metal species with QSA were tested in the presence
of surfactants and exploited chromatographically in very low
concentrations.
Thus the cationic surfactants were widely used for the
enhancement of fluorescence of metal complexes with QSA 4 .
The attention was also paid to the fluorimetric determination
of Al with QSA also in mixtures with Zn using derivative
synchronous scan in the presence of surfactant 5 . The Partial
Least Square Method (PLS) in combination with pH gradient
FIA was used in binary mixtures of ions in complexes with
QSA whose fluorescence was enhanced by the surfactant 6 .
In this paper the fluorescent Al 3+ , Ga 3+ and In 3+ complexes
with QSA were studied in detail in the absence and
presence of surfactants and optimal conditions were recommended
for the determination of particular metals in the presence
of Zephyramine. normal and first derivative spectra
were evaluated.
Experimental
I n s t r u m e n t s
Spectrofluorimeter Aminco Bowman, Series 2 with
1 cm quartz cells, 4 nm exit slits, photomultiplier under 450–
850 V. Sample cell was tempered to 20 °C.
The calculation of the first derivative was made by using
the instrument software using Golay-Savitzky 11-point convolution.
C h e m i c a l s
Standards used, Analytica s.r.o., Prague:
Aluminium chloride 1.000 ± 0.002 g dm –3 containing 5 % HCl
Gallium chloride 1.000 ± 0.002 g dm –3 containing 10 % HCl
Indium chloride 1.000 ± 0.002 g dm –3 •
containing 10 % HCl
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8-Hydroxyquinoline-5-sulphonic acid hydrate (QSA),
Sigma–Aldrich was used without purification
0.1M Benzyldimethyltetradecylammonium chloride
(Zephyramine ® ) – Sigma-Aldrich Co.
0.1M 1-ethoxykarbonylpentadecyltrimethylammonium
bromide (Septonex ® )–Sigma-Aldrich Co.
0.1M Dodecylbenzyldimethylammonium bromide (Ajatin
® ) – Sigma-Aldrich Co.
1% Didodecyldimethylammonium bromide – Sigma-
Aldrich Co.
1% Polyoxyethylene(23) lauryl ether (Brij 35) – Sigma-
Aldrich Co.
1% Hexadecyltrimethylammonium chloride – Fluka.
1% 4-(1,1,3,3-Tetramethylbutyl)phenyl-polyethylene
glycol (Triton X-100) – Calbiochem Co.
0.1 M Sodium dodecylsulphate (SDS) - BDH Chemicals,
England.
E v a l u a t i o n o f D a t a
The limits of detection X D α and XD β calculated according
to Graham 7 follow from the calibration plots and their
confidence intervals were compared with those from multiple
measurements of the background according to IUPAC 8 .
The stoichiometry of complexes was evaluated by using
the modified continuous variations method 9 in the absence
and presence of cationic surfactant Zephyramine. The fluorescence
was measured for several sums of equimolar solutions,
where c o = c M + c L .
Results
The complexes of 8-Hydroxyquinoline-5-sulphonic acid
with Al, Ga, and In produce an outstanding fluorescence for
wavelengths over 430–600 nm with λ max at 495 nm for Al,
λ max at 504 nm for Ga and λ max at 519 nm for In. The corresponding
excitation λ max are 360 nm, 365 nm and 367 nm.
The fluorescence shows considerable pH dependence which
reaches the maximum in solution with c L = 7.4 × 10 –5 M
Fig. 1. Excitation(a) and emission(b) spectra of Aluminium(III)
in the presence of 7.4 × 10 –5 mol dm –3 QSA at 620 V in dependence
on concentration of Al(III) at ph 4
1 – 1.6 μg cm –3 , 2 – 0.8 μg cm –3 , 3 – 0.4 μg cm –3 , 4 – 0.2 μg cm –3 ,
5 – 0.05 μg cm –3 , 6 – 0 μg cm –3