Selective Determination of Verapamil in Pharmaceutics and Urine Using a Boron‐doped Diamond Electrode Coupled to Flow Injection Analysis with Multiple‐pulse Amperometric Detection

• Published in: Electroanalysis (New York, N.Y.) N.Y.), 2018-08, Vol.30 (8), p.1880-1885
• Main Authors: Barbosa Lima, Amanda, Ferreira, Lucas Franco, Barbosa, Sandro Luiz, de Souza Gil, Eric, Amorim Bezerra da Silva, Rodrigo, Pio dos Santos, Wallans Torres
• Format: Article
• Language: English
• Subjects: Antiarrhythmic drugs; BDD; FIA; Multiple Pulse Amperometry; Pharmaceutical Analysis
• ISSN: 1040-0397; 1521-4109
• DOI: 10.1002/elan.201800206

This work presents a simple and low‐cost method for fast and selective determination of Verapamil (VP) in tablets and human urine samples using a boron‐doped diamond working electrode (BDD) coupled to a flow injection analysis system with multiple pulse amperometric detection (FIA‐MPA). The electrochemical behaviour of VP in 0.1 mol L−1 sulfuric acid showed three merged oxidation peaks at around +1.4 V and upon reverse scan, one reduction peak at 0.0 V (vs. Ag/AgCl). The MPA detection was performed applying a sequence of three potential pulses on BDD electrode: (1) at +1.6 V for VP oxidation, (2) at +0.2 V for reduction of the oxidized product and (3) at +0.1 V for cleaning of the working electrode surface. The FIA system was optimized with injection volume of 150 μL and flow rate of 3.5 mL min−1. The method showed a linear range from 0.8 to 40.0 μmol L−1 (R>0.99) with a low limit of detection of 0.16 μmol L−1, good repeatability (RSD