Disposable Printed Electrode Based on Chinese Shellac and Carbon Black for Melatonin Detection

Screen-Printed Electrodes (SPE) have emerged as an innovative technology in the field of electrochemical sensors, offering advantages such as ease of fabrication, potential for miniaturization, large-scale production of carbon electrodes at relatively low cost, with reproducibility and the possibility to be disposable [1-2]. In this work was developed a sensor based on a conductive ink composed of carbon black, Chinese shellac, and acetone, resulting in an electrochemical device printed by screen-printing technique. Characterizations, including scanning electron microscopy, Fourier-transform infrared spectroscopy, x-ray diffraction and electrochemical were performed. To demonstrate the analytical potential of the SPE, it was used for the determination of melatonin, a hormone that regulates the sleep cycle in human beings [3]. The electrochemical behavior and determination of melatonin were investigated using cyclic voltammetry and square wave voltammetry, where its oxidation peak was observed at 0.7V. The optimization of parameters of the technique, step, amplitude, and frequency, was also carried out as well as the pH. Thus, the analytical curve was obtained with a linear range between 1.0 to 100 µmol L−1 , and a detection limit of 0.1 µmol L−1 . In addition, addition and recovery analyses were performed in synthetic urine samples, in which observed values ranged from 86.7% to 110%. Based on the results, it can be concluded that the developed conductive ink has favorable characteristics for the fabrication of printed electrodes and that the analytical device shows promising results for melatonin detection.

[1] J.H.S. Carvalho, et.al. Sensors and Actuators Reports, 3(2021) 100056.

[2] R.C. Freitas, et al. Journal of Electroanalytical Chemistry, 897(2021) 115550.

[3] J.R. Camargo, et al. Talanta, 208(2020) 120458