ORIGINAL PAPER Acrylonitrile-butadiene-styrene (ABS) composite electrode for the simultaneous determination of vitamins B 2 and B 6 in pharmaceutical samples Grasielli C. de Oliveira 1 & Lucas C. Pereira 1 & Ana L. Silva 1 & Felipe S. Semaan 1 & Marilza Castilho 2 & Eduardo A. Ponzio 1 Received: 13 July 2017 /Revised: 6 January 2018 /Accepted: 7 January 2018 /Published online: 12 February 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract A lab-made affordable composite electrode based on acrylonitrile-butadiene-styrene (ABS) and graphite was developed and applied for the simultaneous determination of vitamins B 2 (riboflavin, VB 2 ) and B 6 (pyridoxine, VB 6 ) in pharmaceutical samples. Different ABS-graphite composite electrodes (AGCE) were prepared in proportions ranging from 40 to 80% (graphite, m/m) and characterized by a many complimentary techniques such as thermogravimetry (TG), Raman spectroscopy, Fourier transform-infrared (FTIR), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron micros- copy (SEM), and atomic force microscopy (AFM). Differential pulse voltammetry (DPV) was employed for analytical purposes, being several parameters investigated to determine the optimum experimental conditions. Best performance was obtained using as electrolyte 0.1 mol L -1 acetate buffer solution (pH 4.0), with a pulse amplitude of 100 mV, a scan increment of 5 mV, a modulation of time of 0.05 s, and a time interval of 0.5 s, resulting in a scanning rate of 10 mV s -1 . The use of a 70% AGCE electrode under optimized conditions provided as linear responses for VB 2 and VB 6 intervals from 0.25 to 1.2 μmol L -1 (r = 0.997), and from 25 to 454 μmol L -1 (r = 0.989), respectively, with limits of detection of 0.15 μmol L -1 for VB 2 and 10 μmol L -1 for VB 6 . The AGCE presented satisfactory results for the simultaneous determination of VB 2 and VB 6 in commercially available tablets, with recoveries between 99.5 and 98.0%, being those statistically compatible to those found by a reference spectropho- tometric procedure. Keywords Composite electrode . Graphite . ABS . Pyridoxine . Riboflavin Introduction The term Bvitamin^ comes from vital amine, a class of essential nutrients which acts, even in small amounts, in many different biochemical processes in the human body, and since they are not synthesized by the own organism, people must have a suit- able uptake to obtain them from food or dietary supplements. Such category of nutrients can be classified as either water soluble (vitamin C and the B group) or fat soluble (A, D, E, K). Vitamin B 2 (VB 2 ) or riboflavin, is a required compound for the normal metabolic activity of the human body by mediating the conversion of other vital nutrients like carbohydrates, fats, and proteins into ATP. Inadequacy of VB 2 uptake results in various problems such as itching and burning eyes, sensitivity to light, sore tongue, and peeling skin. In the case of vitamin B 6 (VB 6 ), it must be considered that it has different chemical forms (pyridoxine, pyridoxal, pyridoxamine, and their Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10008-018-3897-z) contains supplementary material, which is available to authorized users. * Grasielli C. de Oliveira grasiellimt@gmail.com 1 Grupo de Eletroquímica e Eletroanalítica (G E), Instituto de Química, Universidade Federal Fluminense, Campus Valonguinho, Niterói, RJ CEP 24020-141, Brazil 2 Grupo de Eletroanalítica e Novos Materiais (GENMAT), Departamento de Química, Universidade Federal de Mato Grosso, Cuiabá, MT CEP 78060-900, Brazil Journal of Solid State Electrochemistry (2018) 22:1607–1619 https://doi.org/10.1007/s10008-018-3897-z