Analytical and Bioanalytical Electrochemistry is an international scientific journal published online by the Center of Excellence in Electrochemistry at the University of Tehran, Tehran, Iran. The journal was published quarterly from 2009 to 2011, bimonthly from 2011 to 2018, and has been published in at least eight issues per year since 2018. Analytical and Bioanalytical Electrochemistry - 12 2 2020 02 01 Determination of Nicotinic Acid by Square Wave Voltammetry on a Carbon Paste Electrode: the Crucial Effect of Electrode Composition and Analytical Conditions 250 262 38718 EN Taher Alizadeh Department of Analytical Chemistry, Faculty of Chemistry, University College of Science, University of Tehran, Tehran, Iran P.O. Box 14155-6455, Tehran, Iran Somayeh Amjadi Journal Article 2019 11 10 The foregone studies have shown that nicotinic acid cannot produce noticeable reductive signal at carbon-based electrodes without appropriate modification of the electrode. This is an obvious reason that mercury is known as the main electrode material for electro-reduction of nicotinic acid. In this study, it has been shown that it is possible to create a remarkable reduction signal for NA at a carbon paste electrode (CPE) without any modification. This achieved by precisely adjustment of electroanalysis pH, appropriately choosing of binder kind, precisely controlling of the percentage of the binder in the electrode composition and utilizing of an effective voltammetric technique. A carbon paste electrode, containing 30% of n-eicosane (as binder) was shown to be the best electrode for NA determination. It was also shown that utilizing of square wave voltammetry in place of differential pulse voltammetry led to remarkably improvement in the analytical signal of NA. The pH value of the electroanalysis solution was shown to be a crucially effective factor for creating of NA signal and an optimum value of pH equal to 2.2 was chosen as the best pH condition. The optimized method exhibited a dynamic concentration linear range of 3.0×10⁻⁶-3.0×10⁻³ molL^-1 with a detection limit of 5.63×10⁻⁷ molL^-1. As an analytical application, the proposed sensor was successfully used for determination of nicotinic acid in the urine, serum and pharmaceutical samples. https://www.abechem.com/article_38718_54e6004b6582e10b9133900cf885a313.pdf