Carbon black as a glassy carbon electrode modifier for high sensitive melatonin determination

Carbon nanomaterials are becoming a significant part of science development nowadays. In this work, carbon black nanopowder was used as an electrode modifier in order to improve sensitivity of glassy carbon electrode. A rapid and high sensitive method of melatonin determination was successfully developed on glassy carbon electrode modified with carbon black using differential pulse voltammetry. The electrochemical behaviour of melatonin electro oxidation on carbon black layer was investigated using cyclic voltammetry. A linear voltammetric response was obtained for analyte in the concentration range from 0.05·10− 6 mol L− 1 (1.16·10− 5 g L− 1) to 12.0·10− 6 mol L− 1 (2.78·10− 3 g L− 1), with a detection limit of 1.9·10− 8 mol L− 1 for preconcentration time of 45 s. Repeatability of method was determined as RSD % for melatonin concentration of 2·10− 6 mol L− 1 as 1.3% (n = 7). The proposed method was successfully applied and validated by studying the recovery of melatonin in different pharmaceutical products. Amperometric measurements of melatonin were performed as well to indicate the possibility of its fast and accurate determination.