Abstract
A proficient and cost-effective electrochemical method for the determination of DL-methionine (DLM) has been successfully developed. The in-situ single-step AgO modification of the graphite pencil electrode (GPE) was characterized by Field Emission Scanning Electron Microscope (FE-SEM), Energy Dispersed X-ray (EDX), X-ray Photoelectron Spectroscopy (XPS), and cyclic voltammetry. The electrocatalytic activity of the silver ions in 0.10 M NaOH (pH 13.7 ± 0.2) initiated the oxidation reaction of DLM on the GPE surface via Ag2+ metal-induced reaction of hydroxyl radical (OH·). Electrode linearity dependence obtained is given as iμA= 68.1CDLM + 2.99 for a linear range concentration of 60 μM - 500 μM with a correlation coefficient (R2) of 0.986 and limit of detection of 0.42 μM. Effects of potential interferences such as ascorbic acid (AA), l-alanine (Aln) and cysteine was found to be insignificant. The developed detection method was found to be suitable for both voltammetric and amperometric techniques for the development of non enzymatic sensor of DLM, and its real life application in human serum sample by standard addition method with a correlation coefficient (R2) of 0.999.
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