Determination of the speciation of aluminum(III) in natural waters by adsorption stripping voltammetry and complexation with AlIII–solochrome violet RS

The biological effects of aluminium have received much attention in recent years. Speciation of Al is of basic relevance as it concerns its reactivity and bioavailability. A differential pulse voltammetry (DPV) procedure is proposed for speciation analysis of AlIII in natural waters and biological fluids using six catechols (L-dopa, dopamine, epinephrine, norepinephrine, caffeic acid and o-benzenediol) as electroactive ligands. The decrease of the DPV anodic peak current for each catechol ligand is linear with the increase of Al concentration. This speciation analysis idea is based on the measurement of the complexation capacity, namely, different affinities of AlIII for catechols and organic ligands under two pH conditions. The labile monomeric Al fraction (mainly inorganic aluminium) is determined at pH 4.6, while the total monomeric Al fraction is determined at pH 8.5. The principle for AlIII speciation analysis by an electrochemical method is discussed. This sensitive and simple fractionation method is successfully applied to the speciation analysis of Al in natural waters and the results agree well with those of Driscoll’s method. The speciation analysis of Al in biological fluids is also explored and the results are compared with those obtained by ultrafiltration and dialysis. Compared with other speciation protocols the electrochemical method possesses some remarkable advantages: rapidity, high sensitivity, cheap instrumentation and a simple operation procedure.

Speciation analysis of aluminium(III) in natural waters and biological fluids by complexing with various catechols followed by differential pulse voltammetry detection

Two alternative sample mineralization procedures to permit subsequent polarographic determination of total soluble aluminium in haemodialysis water

An electrochemical procedure is proposed for the speciation of aluminum (Al) by derivative adsorption chronopotentiometry on a hanging mercury drop electrode (HMDE) using pyrocatechol violet (PCV) as a complexing agent. Labile monomeric Al fraction (mainly inorganic Al) was determined at pH 4.9 (accumulation time 60 s, accumulation potential −0.45 V, PCV concentration 1.5×10−6 mol dm−3 and stripping current 5 μA), while total monomeric Al fraction was determined at pH 8.2 (accumulation time 60 s, accumulation potential −0.50 V, PCV concentration 2.5×10−6 mol dm−3 and stripping current 5 μA). This sensitive and simple fractionation method was successfully applied to the speciation of Al in natural water samples. Five fractions were determined and measured: i) labile monomeric Al (Ali); ii) total monomeric Al (Ala); iii) acid reactive Al (Alr); iv) nonlabile monomeric Al (Alo); v) acid soluble Al (Als). The results were satisfactorily in agreement with those of the 8-hydroxyquinoline extraction/ion exchange method.

Aluminum Speciation with Adsorptive Pyrocatechol Violet-Al(III) Complex by Derivative Adsorption Chronopotentiometry

The determination of aluminum in water samples is performed with capillary electrophoresis after a convenient preconcentration procedure involving simple evaporation and subsequent filtration. By using a fluorescence detector, a detection limit lower than 20 μ/L aluminum is readily obtained. Only one peak from the aluminum-lumogallion complex is observed, which indicates the elimination of interference from foreign ions and lumogallion. analytical chemists to exploit the high separation efficiency and instrumental simplicity for environmental analysis (15,16). However, to our knowledge, there has been no report to date on the determination of trace levels of aluminum in water by cap­ illary electrophoresis (CE). In this paper, the determination of aluminum in water samples was performed by detection of the fluorescence from aluminum-lumogallion complex after it had been separated from potential interferences by using CE. The results were quite close to those obtained by using induc­ tively coupled plasma-mass spectrophotometry (ICP-MS).

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Determination of Trace Levels of Aluminum by Capillary Electrophoresis with Lumogallion Fluorometric Detection

The determination of total aluminum in water by furnace atomic absorption spectrometry is best performed with a prior sample treatment with 1% HNO3 + 2% H2O2 or Acid Alizarin Violet N: detection limits of a few μgL−1 are reliably obtained. Ionic aluminum may be measured at levels down to 25 μgL−1 by differential pulse polarography of the aluminum complex with Acid Alizarin Violet N; excesses of Fe3+, Cl−, and EDTA interfere.

A. Karen Brichta

Papers

Trace analysis for aluminum by furnace atomic absorption spectroscopy and differential pulse polarography