The quantification of methyldopa in pharmaceuticals has been carried out using a glassy carbon electrode（GCE） modified with multi-walled carbon nanotubes（MWCNTs）. Methyldopa exhibited a quasi-reversible response w...The quantification of methyldopa in pharmaceuticals has been carried out using a glassy carbon electrode（GCE） modified with multi-walled carbon nanotubes（MWCNTs）. Methyldopa exhibited a quasi-reversible response with a peak potential separation of 473 m V on a bare GCE. However, the cyclic voltammetric behaviour of methyldopa was improved with the increase of the amount of MWCNTs. It was also shown that the electrocatalytic activity of the electrode towards the response of methyldopa was higher with larger amount of film on the surface. The results showed that the peak current was proportional to the concentration of methyldopa with a linear dynamic range of 0.005-0.388 mmol/L and a detection limit of 1.0 nmol/L was obtained using square wave voltammetry. The experimental data showed that the detection limit of methyldopa and peak separation from interfering compounds such as ascorbic acid（AA） and uric acid（UA） were improved using the proposed procedure. The method was successfully applied for the determination of methyldopa in pharmaceuticals.展开更多
The drug administered for any disease may play an unwanted function in biological system. They may have multiple counter effects, one of which is their interaction to bioactive metals. Iron is most common bio essentia...The drug administered for any disease may play an unwanted function in biological system. They may have multiple counter effects, one of which is their interaction to bioactive metals. Iron is most common bio essential metal and is reported to interact with antihypertensive drug methyldopa. In the present study, above said complex is analyzed by UV-Visible spectrophotometry. Formation constant of the complex is calculated by using mole ratio method and single point statistical method which is in the range of 1010, values are also calculated which are independent of pH like formation constant. Absorbance maxima were found to be dependent on pH. At lower pH complex shows two broad bands centered at 430 nm and 730 nm. With the rise in pH later peak shifts toward lower wavelength, so 615 nm is selected for further studies. Molar extinction coefficient of the complex is explored by serial dilution method. At all wavelengths it increases with increase in pH. Mole ratio and slope ratio methods are used for exploring stoichiometry. Metal to ligand combining ratio in the complex is 1:2 at pH 4.0 and pH 4.5 while 1:3 at pH 5.0 and pH 5.5.展开更多
Sensitive and simple colorimetric method was developed for determination of methyldopa and terbutaline sulphate in pure and pharmaceutical dosage forms.The method was based on reduction of silver ions by the cited dru...Sensitive and simple colorimetric method was developed for determination of methyldopa and terbutaline sulphate in pure and pharmaceutical dosage forms.The method was based on reduction of silver ions by the cited drugs in basic medium at 90℃ to silver nanoparticles in the presence of stabilizing agent as polyvinylpyrrolidone.The formed silver nanoparticles were distinguished by UV-Vis absorption spectroscopy indicating the characteristic surface plasmon resonance which can be also observed as intense yellow color solution.The plasmon absorbance of the silver nanoparticles was measured at 410 nm for quantitative estimation of methyldopa and terbutaline sulphate over the range of 80-480 and 40-600 ng/mL respectively.Limit of detection was obtained as 26,13 ng/mL for methyldopa and terbutaline sulphate respectively.The eco-friendly developed method could be successfully applied to the pharmaceutical formulations with studying the interference of different excipients.展开更多
基金the financial support from the University of Harran (HüBAK)
文摘The quantification of methyldopa in pharmaceuticals has been carried out using a glassy carbon electrode（GCE） modified with multi-walled carbon nanotubes（MWCNTs）. Methyldopa exhibited a quasi-reversible response with a peak potential separation of 473 m V on a bare GCE. However, the cyclic voltammetric behaviour of methyldopa was improved with the increase of the amount of MWCNTs. It was also shown that the electrocatalytic activity of the electrode towards the response of methyldopa was higher with larger amount of film on the surface. The results showed that the peak current was proportional to the concentration of methyldopa with a linear dynamic range of 0.005-0.388 mmol/L and a detection limit of 1.0 nmol/L was obtained using square wave voltammetry. The experimental data showed that the detection limit of methyldopa and peak separation from interfering compounds such as ascorbic acid（AA） and uric acid（UA） were improved using the proposed procedure. The method was successfully applied for the determination of methyldopa in pharmaceuticals.
文摘The drug administered for any disease may play an unwanted function in biological system. They may have multiple counter effects, one of which is their interaction to bioactive metals. Iron is most common bio essential metal and is reported to interact with antihypertensive drug methyldopa. In the present study, above said complex is analyzed by UV-Visible spectrophotometry. Formation constant of the complex is calculated by using mole ratio method and single point statistical method which is in the range of 1010, values are also calculated which are independent of pH like formation constant. Absorbance maxima were found to be dependent on pH. At lower pH complex shows two broad bands centered at 430 nm and 730 nm. With the rise in pH later peak shifts toward lower wavelength, so 615 nm is selected for further studies. Molar extinction coefficient of the complex is explored by serial dilution method. At all wavelengths it increases with increase in pH. Mole ratio and slope ratio methods are used for exploring stoichiometry. Metal to ligand combining ratio in the complex is 1:2 at pH 4.0 and pH 4.5 while 1:3 at pH 5.0 and pH 5.5.
文摘Sensitive and simple colorimetric method was developed for determination of methyldopa and terbutaline sulphate in pure and pharmaceutical dosage forms.The method was based on reduction of silver ions by the cited drugs in basic medium at 90℃ to silver nanoparticles in the presence of stabilizing agent as polyvinylpyrrolidone.The formed silver nanoparticles were distinguished by UV-Vis absorption spectroscopy indicating the characteristic surface plasmon resonance which can be also observed as intense yellow color solution.The plasmon absorbance of the silver nanoparticles was measured at 410 nm for quantitative estimation of methyldopa and terbutaline sulphate over the range of 80-480 and 40-600 ng/mL respectively.Limit of detection was obtained as 26,13 ng/mL for methyldopa and terbutaline sulphate respectively.The eco-friendly developed method could be successfully applied to the pharmaceutical formulations with studying the interference of different excipients.
