Ian C. Hamilton

The study of a membrane for extracting gold(III) from hydrochloric acid solutions

A membrane is described consisting of Aliquat 336 chloride immobilized in poly(vinyl chloride) (PVC) which extracts gold(III) selectively from hydrochloric acid solutions in the presence of a 500-fold higher concentration of copper(II). Gold is recovered from the membrane by stripping with a thiourea solution. The stability of the membrane is reported in terms of the extent of leaching of the reagent from the membrane in aqueous solutions.

Mathematical modelling of membrane extraction of gold(III) from hydrochloric acid solutions

Abstract A mathematical model describing the selective extraction of gold(III) from hydrochloric acid solution into a membrane consisting of Aliquat 336 chloride immobilized in poly(vinyl chloride) (PVC) is developed. The extraction rate is assumed to be governed by both the rate of chemical reactions occurring at the interface and the diffusion of the Aliquat 336 chloride species within the membrane. The fairly good agreement between the model and experimental results confirms its validity and shows that the model can be used successfully for the mathematical description and optimisation of membrane extraction utilised in analytical and process systems as well as in environmental chemistry.

Photocured polymers in ion-selective electrode membranes

A fast and convenient method is reported for preparing ion-selective electrode membrane based on bisphenol. A epoxyacrylate, 1,6-hexanedioldiacrylate and benzophenone photoinitiator. A calcium-selective electrode is used as example; responses are Nernstian in the range 10−1–10−5 M with the calcium salt of bis-[4-(1′,1′,3′,3′-tetramethylbutyl)phenyl]phosphoric acid as the active substance.

A multi-ion sensor cell and data-acquisition system for flow injection analysis

Abstract The flow-injection system described is used for the determination of four ions simultaneously with detection by solid-contact polymer-membrane ion-selective electrodes. The construction of the flow cell and data-acquisition system are discussed. The programming language FORTH facilitates the fast data acquisition required for flow injection analysis. The utility of the system is demonstrated by applying it to the simultaneous determination of potassium, calcium, nitrated and chloride in soil extracts; the results are compared with standard procedures.

Photo-cured polymers in ion-selective electrode membranes : Part 3. A Potassium Electrode for Flow Injection Analysis

Abstract The preparation of a calcium-selective electrode based on a photo-cured polymer membrane containing a neutral carrier is described. This electrode is suitable for use in flow injection analysis because of its fast initial response and the harness and mechanical strength of the membrane.

Versatile manifold for the simultaneous determination of ions in flow injection analysis

A flow injection analysis system is described for the simultaneous determination of several ions in a single sample using a combination of potentiometric and spectrophotometric detection. A composite manifold has been designed consisting of a flow cell containing four ion-selective electrodes and two spectrophotometric transducer flow cells. The system has been applied to the determination of K+, Ca2+, NH4+, Cl–, NO3– and PO43– ions in a number of plant nutrient solutions.

Determination of free sulphur dioxide in red wine by alternating current voltammetry

Anthocyanins and oxygen interfere in the determination of ‘free SO2’ in red wine by d.c. and differential-pulse voltammetry. However, the a.c. voltammetric behaviour of anthocyanins extracted from red wine shows that there is no interference in the determination of SO2. Furthermore, there is minimal interference from oxygen which overcomes the need for de-oxygenation and its associated loss of SO2. A phase-selective second harmonic a.c. voltammetric procedure is described for the determination of free SO2 in red wine. The results of the analyses of several red wine samples are compared with those given by the spectrophotometric method accepted by the Australian wine industry.

Flow-injection spectrophotometric determination of fluoride by using the zirconium/alizarin red S complex

A spectrophotometric flow-injection procedure is described for fluoride in aqueous samples. The method is based on the decrease in absorbance of the zirconium/alizarin red S complex at 520 nm; linear response is obtained for the range 0.1–10 mg l−1 fluoride at a sampling rate of 100 h−1. Aluminum(III), iron(III) and phosphate interfere.

Determination of the quaternary ammonium ion components of Aliquat 336 by electrospray mass spectrometry

A procedure is described for the identification and determination of the quaternary ammonium ion components of the commercial solvent extraction reagent Aliquat 336 using Electro Spray Mass Spectrometry (ESMS). The procedure is extremely rapid when compared with an existing procedure based on gas chromatography and produces comparable results in terms of accuracy and precision.

Photo-cured polymers in ion-selective electrode membranes : Part 4. An Ultraviolet Laser Cured Membrane for Potassium

Abstract The preparation of an ultraviolet-laser cured polymer membrane electrode selective for potassium is reported. The epoxyacrylate membrane in this valinomycin-based electrode is cured without using a photoinitiator. This leads to improved compatibility of the membrane components and to better response characteristics for the electrode, particularly for use in flow injection, compared with an earlier procedure in which a photoinitiator was used in the curing process. An improved method for preparing very thin films on the metallic substrate of the electrode provides a very fast electrode response.