Fast determination of aluminium reactive to 1,2-dihydroxyanthraquinone-3-sulfonic acid in sea-water

Abstract

A modification of the method for the determination of aluminium by adsorptive cathodic stripping voltammetry of its 1,2-dihydroxyanthraquinone-3-sulfonic acid (DASA) complex is described. Rapid determination is achieved by using staircase modulation and high potential scan speeds (20 V s-1). Square wave modulation was found inefficient above 2 V s-1 because the potential pulse is distorted by the ohmic drop. The staircase modulation is also distorted, but the determination is not disturbed and high faradaic currents are obtained. The method was not sensitive to the turbulence of the solution during the scan, as a short scan time is required (several ms) and very high currents (FA) are obtained from the reduction of the DASA-A1 complex. Interference from oxygen was also overcome as DASA-A1 to oxygen current ratios are increased and background subtraction is feasible. The natural calcium concentration of sea-water enhances the DASA-A1 peak height; calcium should therefore be added to fresh water to enhance the determination. The method is proposed in particular for the determination of A1 on board oceanographic vessels. There is no need to purge samples, noise due to vibrations of motions of the ship during scanning is avoided, and the sensitivity is enhanced. The total analysis time can be decreased to 8-12 min per sample by using an adsorption time of 40 s. The technique has been tested s u c d u l l y for the on-board determination of Al in sea-water. Results obtained for seawater samples irradiated by ultraviolet tight were similar to those obtained using an existing fiuorimetric method.

Determination of Aluminum by Adsorptive Cathodic Stripping Voltammetry with 1,2‐Dihydroxyanthraquinone‐3‐Sulfonic Acid (DASA): Effect of Thin Mercury Film Electrode

“…Previous work on the Al-DASA system [5,7] reported that a peak at À 0.8 V was consistently present in stripping voltammograms performed at a HMDE. Furthermore, the current response for this peak is greater than for the peak P4 when analyzed at HMDEs.…”

“…Previous published work showed that the Al/DASA complex is reducible on a HMDE electrode, producing two voltammetric peaks [5,7]. The use of the TMFE was investigated for the electroanalytical determination of aluminum through cathodic stripping voltammetry with DASA.…”

Antivibration Electrode Support for Shipboard Stripping Voltammetry

“…One way to minimize these problems is to use high-frequency square-wave scans, or fast linear-sweep scans [3]. The fast scans tend to lead to increased peak currents, which might then become greater than the interfering capacitance currents, albeit at a loss of resolution for poorly reversible reactions.…”

Voltammetric determination of aluminum(III) using a reagentless sensor fabricated by sol–gel process

“…Aluminum, like alkaline earth and rare earth metal ions, cannot be easily determined by conventional voltammetry because of the difficulty in reducing them at the electrode in aqueous solutions. The development of an adsorptive complex wave relying on the electrochemical responses of organic chelants and/or their "Al-organic ligand complexes" overcame those obstacles [3][4][5]. Chemically modified electrodes, which were prepared by adsorption of dye, were also developed for the determination of aluminum due to their selectivity and simple detection instrumentation [6,7].…”