Antioxidant Investigation of Marjoram using Aminated CarbonNanoparticles/Glassy Carbon Modified Electrode

Development of new methods for determination of antioxidants in natural compounds hasreceived considerable interests in recent years. Various methods such as chromatography,spectrophotometry and capillary electrophoresis (CE) have been developed for this purpose.These techniques are limited by poor accuracy or the need for expensive instrumentation withhigh operating costs. Among the various reported methods, electrochemical techniques are oftenpreferred because of their high selectivity, rapid detection, low cost and their lack of a substantialsample preparation setup [1]. Marjoram belongs to the mint family. Flowers and leaves are theparts of the plant are used in medicinal preparations. Marjoram is packed with vitamins andminerals, that gives the following health related properties: anti-microbial, anti-septic, antiinflammatory,anti-depressant, anti-viral and antioxidant. Gallic acid is a natural antioxidant thatnot synthesized in the human body [2]. It has reported that the main compound responsible forantioxidant properties of Marjoram is Gallic acid. In this study, glassy carbon electrode has beenmodified by using Alginate/CNP-NH3+ bilayer. The formation of bilayer is based on electrostaticinteraction between two components. The modified electrode has been studied using cyclicvoltammetry, electrochemical impedance spectroscopy (ESI) and scanning electron microscopy(SEM). The modified electrode has been employed for determination of gallic acid. The gallicacid has been used as standard for antioxidant properties of Marjoram.MethodVoltammetric experiments were performed using a Metrohm Computrace VoltammetricAnalyzer model 797 VA. To evaluate the electrochemical sensing ability of the Alginate/CNP NH3+ through Gallic acids, modification of glassy carbon electrode has been performed bycasting method. First 10 mL of alginate solution was casted on the GCE surface and dried in theair to evaporate solvent. Then 10 mL of CNP-NH3+ suspension was casted on the GCE surfaceand dried in the air to evaporate solvent too. The modified electrode has been used forvoltammetric measurements.Result and discussionA glassy carbon electrode modified in situ with bilayer of alginate/CNP-NH3+, and the ability ofelectrode for sensing in Marjoram was investigated. Differential pulse voltammetry has beenemployed as a sensitive method for determination of gallic acid that exists in Marjoram usingstandard addition. Currents versus GA concentration shows linear relationship from 0.5 mM to 0.1 mM with thecorrelation coefficient equal to 0.99 and limit of detection for modified electrode is: 0.43 mMConclusionThe present study demonstrates an excellent approach for the development of a voltammetricsensor for investigating antioxidant properties of some herbs such as Marjoram.

کلیدواژه ها:

Marjoram ، Ascorbic acid ، Gallic acid ، Modified electrode ، Voltammetry ، Antioxidant