title: A highly improved method for sensitive determination of amitriptyline in pharmaceutical formulations using an unmodified carbon nanotube electrode in the presence of sulfuric acid.
abstract: The present paper describes a novel, simple and reliable differential pulse voltammetric method for determining amitriptyline (AMT) in pharmaceutical formulations. It has been described for many authors that this antidepressant is electrochemically inactive at carbon electrodes. However, the procedure proposed herein consisted in electrochemically oxidizing AMT at an unmodified carbon nanotube paste electrode in the presence of 0.1 mol L(-1) sulfuric acid used as electrolyte. At such concentration, the acid facilitated the AMT electroxidation through one-electron transfer at 1.33 V vs. Ag/AgCl, as observed by the augmentation of peak current. Concerning optimized conditions (modulation time 5 ms, scan rate 90 mV s(-1), and pulse amplitude 120 mV) a linear calibration curve was constructed in the range of 0.0-30.0 μmol L(-1), with a correlation coefficient of 0.9991 and a limit of detection of 1.61 μmol L(-1). The procedure was successfully validated for intra- and inter-day precision and accuracy. Moreover, its feasibility was assessed through analysis of commercial pharmaceutical formulations and it has been compared to the UV-vis spectrophotometric method used as standard analytical technique recommended by the Brazilian Pharmacopoeia.
authors.affiliation: Departamento de Química, Universidade Estadual de Londrina (UEL), Centro de Ciências Exatas, Rodovia Celso Garcia Cid, PR 445 Km 380, CEP 86050-482, Londrina, Parana, Brazil.
authors.forename: Eduardo Henrique
authors.initials: EH
authors.lastname: Duarte
authors.affiliation: Departamento de Química, Universidade Estadual de Londrina (UEL), Centro de Ciências Exatas, Rodovia Celso Garcia Cid, PR 445 Km 380, CEP 86050-482, Londrina, Parana, Brazil.
authors.forename: William Pereira
authors.initials: WP
authors.lastname: dos Santos
authors.affiliation: Departamento de Química, Universidade Estadual de Londrina (UEL), Centro de Ciências Exatas, Rodovia Celso Garcia Cid, PR 445 Km 380, CEP 86050-482, Londrina, Parana, Brazil.
authors.forename: Felipe Fantinato
authors.initials: FF
authors.lastname: Hudari
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-Carlense, CEP 13566-590, São Carlos, Sao Paulo, Brazil.
authors.forename: José Luiz
authors.initials: JL
authors.lastname: Bott Neto
authors.affiliation: Departamento de Química, Universidade Estadual de Londrina (UEL), Centro de Ciências Exatas, Rodovia Celso Garcia Cid, PR 445 Km 380, CEP 86050-482, Londrina, Parana, Brazil.
authors.forename: Elen Romão
authors.initials: ER
authors.lastname: Sartori
authors.affiliation: Departamento de Química, Universidade Estadual de Londrina (UEL), Centro de Ciências Exatas, Rodovia Celso Garcia Cid, PR 445 Km 380, CEP 86050-482, Londrina, Parana, Brazil.
authors.forename: Luiz Henrique
authors.initials: LH
authors.lastname: Dall'Antonia
authors.affiliation: Departamento de Ciências Naturais, Universidade Federal de São João del Rei, Campus Dom Bosco, Praça Dom Helvécio 74, Fábricas, 36301-160 São João del Rei, Minas Gerais, Brazil.
authors.forename: Arnaldo César
authors.initials: AC
authors.lastname: Pereira
authors.affiliation: Departamento de Química, Universidade Estadual de Londrina (UEL), Centro de Ciências Exatas, Rodovia Celso Garcia Cid, PR 445 Km 380, CEP 86050-482, Londrina, Parana, Brazil; Instituto Nacional de Ciência e Tecnologia (INCT) de Bioanalítica, Universidade Estadual de Campinas (UNICAMP), Instituto de Química, Departamento de Química Analítica, Cidade Universitária Zeferino Vaz s/n, CEP 13083-970, Campinas, Sao Paulo, Brazil. Electronic address: ctarleyquim@yahoo.com.br.
authors.forename: César Ricardo Teixeira
authors.initials: CR
authors.lastname: Tarley
mesh_terms: D000327:Adsorption; D000639:Amitriptyline / Q000032:analysis* / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D005079:Excipients / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D004364:Pharmaceutical Preparations / Q000737:chemistry; D013464:Sulfuric Acids / Q000737:chemistry
chemical_list: D005079:Excipients; D037742:Nanotubes, Carbon; D004364:Pharmaceutical Preparations; D013464:Sulfuric Acids; D000639:Amitriptyline; C033158:sulfuric acid
keywords: Carbon nanotube paste electrode; Differential pulse voltammetry; Sulfuric acid medium; Tricyclic antidepressants