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Selective Determination of Verapamil in Pharmaceutics and Urine Using a Boron‐doped Diamond Electrode Coupled to Flow Injection Analysis with Multiple‐pulse Amperometric Detection
Author(s) -
Barbosa Lima Amanda,
Ferreira Lucas Franco,
Barbosa Sandro Luiz,
de Souza Gil Eric,
Amorim Bezerra da Silva Rodrigo,
Pio dos Santos Wallans Torres
Publication year - 2018
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201800206
Subject(s) - detection limit , amperometry , flow injection analysis , ascorbic acid , electrode , analytical chemistry (journal) , repeatability , working electrode , chromatography , chemistry , electrochemistry , food science
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<2.2 %; n=10) and sample throughput (45 h −1 ). Selective determination of VP in urine was performed at+0.2 V due to absence of interference from ascorbic and uric acids in this potential. The addition‐recovery tests in both samples were close to 100 % and the results were similar to an official method.