Sabriye Perçin Özkorucuklu

Voltammetric Behaviour of Sulfamethoxazole on Electropolymerized-Molecularly Imprinted Overoxidized Polypyrrole

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.

Voltammetric behavior and determination of doxycycline in pharmaceuticals at molecularly imprinted and non-imprinted overoxidized polypyrrole electrodes

In this paper, electrochemical behavior of a member of tetracycline group compounds doxycyline (DC) was investigated in 20, 30, 40% (v/v) acetonitrile (ACN)-water binary mixture at the pH of 2.0-4.0 prepared Britton-Robinson (BR) buffers, by the differential pulse voltammetric method (DPV). Voltammetric determination of DC was carried out using molecularly imprinted (MIP) and non-imprinted polypyrrole (NIP) modified electrodes. Both types of electrode were prepared by the cyclic voltammetric method. The effect of the ACN-water ratio and pH, on the performance of the MIP electrode was investigated and optimized. The highest anodic signal of DC with MIP electrode was obtained in BR buffer solution was prepared in 30% (v/v) ACN-water at pH 2.0. The detection limit was determined as 4.35×10(-5)M (S/N=3). The method was also applied for electrochemical determination of DC in pharmaceutical samples. The recovery factors for Tetradox(®) and Monodox(®) were found 96.30%, 61.18% respectively with the relative standard deviations 0.46 and 0.54. The results of experiments using two commercial drugs showed that the MIP electrode can be used as a sensor to determine DC in pharmaceuticals.

Electroanalytical Determination of Some Sulfonamides on Overoxidized Polypyrrole Electrodes

The electrochemical behaviours of five sulfonamides (sulfanilamide, sulfadiazine, sulfamerazine, sulfamonomethoxine, sulfamethoxazole) were investigated with overoxidized polypyrrole (OPPy) modified pencil graphite electrodes. The performance of the OPPy electrode was evaluated by differential pulse voltammetry in Britton–Robinson buffer solutions prepared in different ratio of acetonitrile-water binary mixture, between pH 1.5 and 7.0. The highest anodic signals of sulfonamides were obtained in Britton–Robinson buffer solution prepared in 50% (v/v) acetonitrile-water at pH 2.5 and 3.0. The OPPy electrodes exhibited good performance for sulfonamides with wide linear ranges (≈10–5–10–3u2009M), highly reproducible responses (RSD% ≤0.92) and correlation coefficients (≥0.9990). The calculated limits of detection were ~10–6 or 10–7u2009M at 3σ. In order to verify the reliability of the OPPy electrode as a sensor, it is used for determination of sulfamethoxazole in a pharmaceutical tablet. The recovery was found as 95.96% with the RSD% of 0.68. The overoxidized polypyrrole modified pencil graphite electrode showed a stable and reproducible response without any influence of interferent commonly existing in pharmaceutical containing sulfamethoxazole.

Rapid tissue dissolution efficiency of electrically-activated sodium hypochlorite on bovine muscle

Objective: Sodium hypochlorite (NaOCl) is a common antimicrobial and tissue-dissolving irrigant. The aim of this in vitro study is to evaluate and compare dissolution capacities of sodium hypochlorite solutions after electrically activation (E-NaOCl) on bovine muscle specimens at various time periods and concentrations. Materials and Methods: Three sodium hypochlorite solutions of 1.25%, 2.5%, and 5% were tested at 3-min. and 5-min. with and without activation by electrically. Distilled water and NaOCl solutions without electrically activation were used as controls. Pieces of bovine muscle tissue (34 ± 2 mg) were placed in 10 mL of each solution at room temperature. In the group of E-NaOCl, electrically activation was performed through the potentiostat. The tissue specimens were weighed before and after treatment, and the percentage of weight loss was calculated. Results: Weight loss of the tissue increased with the concentration of E-NaOCl and NaOCl. Higher concentration and electrically activation considerably enhanced the efficacy of sodium hypochlorite. The effect of electrically activation on tissue dissolution was much greater than that of same concentrations in the groups of NaOCl (P < 0.001). Tissue weight loss was significantly higher in 2.5% and 5% E-NaOCl at 3 min. than in 2.5% and 5% NaOCl at 5 min. (P < 0.05). There were not any significant differences between the 2.5% E-NaOCl and 5% NaOCl at 5 min. (P > 0.05). Conclusion: Electrically activation can improve the tissue-dissolving effectiveness of sodium hypochlorite.

Determination of sulfamethoxazole in pharmaceutical formulations by flow injection system/HPLC with potentiometric detection using polypyrrole electrode

In this work, it was used a polypyrrole (PPy) electrode as a potentiometric electrochemical detector in a flow injection system in order to determine sulfamethoxazole in pharmaceutical formulations. The PPy electrode was prepared by cyclic voltammetry in acetonitrile solution. A linear relationship was observed over the concentration range of 2.5 × 10-5-1.25 × 10-3 mol L-1 with a correlation coefficient of 0.9977 and limit of detection (LOD) of 1.03 × 10-6 mol L-1 (S/N = 3). The recoveries in tablet and syrup formulations were found as 97.4 and 90.8% with the relative standard deviations of 0.62 and 1.04%, respectively, which closely agree with those measured by high performance liquid chromatography (HPLC) with UV detector. Therefore, it was concluded that the PPy electrode can be used as an alternative novel potentiometric detector material for determination of sulfamethoxazole in pharmaceuticals with the advantages of easy preparation and regeneration capability of the electrode surface.

The effect of micro-electric current and other activation techniques on dissolution abilities of sodium hypochlorite in bovine tissues

BackgroundThe aim of the study was to evaluate the effects of micro-electric current on sodium hypochlorite’s (NaOCl’s) tissue-dissolution abilities, compared with other activation methods, including sonic, ultrasonic, pipetting, and temperature.MethodsBovine muscle tissues (nu2009=u2009154) with standard sizes and weights were prepared and divided into two temperature groups: room temperature and 45xa0°C. Each temperature group was divided into seven sub-groups by activation methods: Du2009=u2009distilled water (−control); NaOClu2009=u20095.25xa0% passive NaOCl (+ control); Pu2009=u20095.25xa0% NaOCl with pipetting; SAu2009=u20095.25xa0% NaOCl with sonic activation; UAu2009=u20095.25xa0% NaOCl with ultrasonic activation; E-NaOClu2009=u20095.25xa0% NaOCl with micro-electric current; and E-NaOClu2009+u2009Pu2009=u20095.25xa0% NaOCl with micro-electric current and pipetting. Specimens were weighed before and after treatment. Average, standard deviation, minimum, maximum, and median were calculated for each group. Resulting data were analyzed statistically using multi-way ANOVA and Tukey HSD tests. The level of the alpha-type error was set atu2009<u20090.05.ResultsAt room temperature, the E-NaOClu2009+u2009P group dissolved the highest amount of tissue (pu2009<u20090.05), and the UA, SA, and P groups dissolved significantly higher amounts of tissue than did the positive control or E-NaOCl groups (pu2009<u20090.05). At 45xa0°C, there was no significant difference between the SA and E-NaOCl groups (pu2009>u20090.05), and the E-NaOClu2009+u2009P group dissolved a higher amount of tissue than any other group (pu2009<u20090.05).ConclusionsUsing NaOCl with micro-electric current can improve the tissue-dissolving ability of the solution. In addition, this method can be combined with additional techniques, such as heating and/or pipetting, to achieve a synergistic effect of NaOCl on tissue dissolution.

Removal of Cr(III) from aqueous solutions using P-EAn and P-MAn/PVDF composite membranes

Abstract In this work, composite membranes were prepared by chemical polymerization of a thin layer of substitute anilines (methylaniline and ethylaniline) in the presence of an oxidant on the surface polyvinylidenefluoride (PVDF) membrane support sheet. Poly-N-ethylaniline (P-EAn) and poly-N-methylaniline (P-MAn)/PVDF composite membranes were obtained from this polymerization. Scanning electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy studies for composite membranes confirmed substitute anilines loading on the PVDF membrane. The membrane thickness and their ion-exchange capacities were also measured. Donnan dialysis experiments were performed using P-EAn and P-MAn/PVDF composite membranes for the removal of chromium (III) from aqueous solution. The flux values (J) of Cr(III) were obtained at 25°C. The flux value of Cr(III) for P-EAn/PVDF composite membranes was higher than the other membrane because of the high ion-exchange capacity.