In this work, preparation of a molecularly imprinted polymer (MIP) film and its recognition properties for sulfamethoxazole were investigated. The overoxidized polypyrrole (OPPy) film was prepared by the cyclic voltammetric deposition of pyrrole (Py) in the presence of supporting electrolyte (tetrabutylammonium perchlorate-TBAP) with and without a template molecule (sulfamethoxazole) on a pencil graphite electrode (PGE). The voltammetric behaviour of sulfamethoxazole on imprinted and non-imprinted (NIP) films was investigated by differential pulse voltammetry (DPV) in Britton-Robinson (BR) buffer solutions prepared in different ratio of acetonitrile-water binary mixture, between the pH 1.5 and 7.0. The effect of the acetonitrile-water ratio and pH, monomer and template concentrations, electropolymerization cycles on the performance of the MIP electrode was investigated and optimized. The MIP electrode exhibited the best reproducibility and highest sensitivity. The results showed that changing acetonitrile-water ratio and pH of BR buffer solution changes the oxidation peak current values. The highest anodic signal of sulfamethoxazole was obtained in BR buffer solution prepared in 50% (v/v) acetonitrile-water at pH 2.5. The calibration curve for sulfamethoxazole at MIP electrode has linear region for a concentration range of 25.10-3 to 0.75 mM (R2=0.9993). The detection limit of sulfamethoxazole was found as 3.59.10-4 mM (S/N=3). The same method was also applied to determination of sulfamethoxazole in commercial pharmaceutical samples. Method precision (RSD<1%) and recoveries (>87%) were satisfactory. The proposed method is simple and quick. The polypyrrole (PPy) electrodes have low response time, good mechanical stability and are disposable simple to construct.

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In this study, the dissociation constants of a series of phenolic acids, including benzoic acid, four hydroxylated derivatives (p-hydroxybenzoic, protocatechuic, vanillic, and gallic), and four hydroxylated cinnamic acid derivatives (p-coumaric, caffeic, ferulic, and sinapinic) have been determined in water by capillary electrophoresis (CE) from the electrophoretic mobilities at different pH value. The pK a values have also been obtained from the absorbance spectra at the maximum of the electrophoretic peaks, which were measured with a diode-array detector (CE-DAD methodology). The pK a values obtained from both methodologies (CE and CE-DAD) have been compared with those previously published in the literature and also with the values predicted by the SPARC online pK a calculator.

In this work, composite cation‐exchange membrane was prepared by chemical polymerization of pyrrole on the surface of the poly(vinylidene fluoride) (PVDF) membrane using ferric ions. The changes in the surface morphologies of non‐modified and polymer‐modified PVDF membrane were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The ion‐exchange capacity, water uptake, and fixed group concentration of the composite membrane were investigated. The polypyrrole/PVDF composite membrane was used for the removal of copper (II), chromium (III), iron (III), and aluminum (III) ions from aqueous solution with Donnan dialysis experiments. The flux values (J) and recovery factors (RF) of Cu(II), Cr(III), Fe(III), and Al(III) were obtained. Because of the smaller ion charge and hydration volume, the transport of the Cu(II) ion is higher than that of the other metals. Copyright © 2011 John Wiley & Sons, Ltd.