Vol.:(0123456789) 1 3 Monatshefte für Chemie - Chemical Monthly (2021) 152:1183–1191 https://doi.org/10.1007/s00706-021-02839-y ORIGINAL PAPER Simple and sensitive electrochemical analysis of ribofavin at functionalized carbon nanofber modifed carbon nanotube sensor D. N. Varun 1,2  · J. G. Manjunatha 1  · N. Hareesha 1  · S. Sandeep 2  · P. Mallu 2  · C. S. Karthik 2  · N. S. Prinith 1  · N. Sreeharsha 3,4  · S. M. Basheeruddin Asdaq 5 Received: 2 June 2021 / Accepted: 11 August 2021 / Published online: 25 August 2021 © Springer-Verlag GmbH Austria, part of Springer Nature 2021 Abstract The present work demonstrates the development of functionalized carbon nanofber and carbon nanotube composite paste electrode towards the electrochemical analysis of ribofavin (RF) in 0.2 M phosphate bufer solution of pH 7.0 in the pres- ence of ascorbic acid. RF shows the enhanced electrochemical reaction at the modifed electrode surface with well-resolved and distinct redox peaks than bare carbon nanotube paste electrode. The material characteristics were analyzed using feld emission scanning electron microscopy, X-ray powder difraction, electrochemical impedance spectroscopy, and cyclic vol- tammetry methods. The proposed electrode gives a fne linear relation between the concentration of RF and oxidation peak current in the linear range of 5.0–60.0 µM with the limit of detection of 15.35 nM and limit of quantifcation of 51.18 nM. Also, the sensing capability of the electrode for RF analysis was tested in B-complex capsule with fne recoveries. Graphic abstract Keywords Ribofavin · Functionalized carbon nanofber · Carbon nanotubes · X-ray powder difraction study · Voltammetry · Electron transfer · Sensors Introduction Vitamins are the vital organic compounds for human health, which are necessary contents in food for the living organ- isms for their regular growth and nutrition. Vitamins are varying in their structure, solubility, and biological charac- ters and their insufciency will lead to many diseases in the human body [1, 2]. Ribofavin (RF, also called vitamin B2) is an elemental water-soluble component that appears in two important co- enzymes of favonoids observed in numerous food compo- nents such as wine, beans, eggs, cheese, and so on [3]. RF is essential for health, tissue maintenance, energy, organic degradation, oxidation, reduction, and redox reactions in the * J. G. Manjunatha manju1853@gmail.com 1 Department of Chemistry, FMKMC College, Constituent College of Mangalore University, Madikeri, Karnataka, India 2 Department of Chemistry, SJCE, JSS Science and Technology University, Mysuru, Karnataka, India 3 Department of Pharmaceutical Sciences, College of Clinical Pharmacy, King Faisal University, 31982, Al-Ahsa, Saudi Arabia 4 Department of Pharmaceutics, Vidya Siri College of Pharmacy, Of Sarjapura Road, Bengaluru 560 035, Karnataka, India 5 Department of Pharmacology, College of Pharmacy, AlMaarefa University, Riyadh, Saudi Arabia