title: Validation of a tubular bismuth film amperometric detector. Determination of diclofenac sodium by multisyringe flow injection analysis.
abstract: A tubular bismuth film electrode (BFE), installed as part of a multisyringe flow injection system, was used as an amperometric detector to determine the concentration of diclofenac sodium in pharmaceutical formulations. A tubular voltammetric detection cell was employed, in which the hydrodynamic flow conditions were not disturbed. This automated method allows the continuous regeneration of the BFE, preventing passivation of the detector and improving the sensitivity of detection. The influence of several variables on this sensitivity, such as the injection volume, deposition time and flow rate were evaluated; a two-level factorial experimental design was employed for this. In optimal conditions, the linear range of the calibration curve varied from 6.0-50.0 micromol L(-1), with a detection limit of 4.3 micromol L(-1). A sampling rate of 90 determinations/h was achieved; the relative standard deviation of analytical repeatability was <3.5%. After 30 injections the bismuth film on the electrode surface was automatically renewed. The method was validated by comparing the results obtained with those provided by RP-HPLC; no significant difference were seen (p<0.05).
authors.affiliation: Centro de Investigaciones Quimicas, Universidad Autonoma del Estado de Hidalgo, Carr. Pachuca-Tulancingo km 4.5, 42060 Pachuca, Hidalgo, Mexico; QUIANE, Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid, Spain. Electronic address: jara78@qa.uva.es.
authors.forename: José A
authors.initials: JA
authors.lastname: Rodríguez
authors.affiliation: QUIANE, Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid, Spain. Electronic address: ebarrado@qa.uva.es.
authors.forename: Enrique
authors.initials: E
authors.lastname: Barrado
authors.affiliation: QUIANE, Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid, Spain. Electronic address: ycastril@qa.uva.es.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Castrillejo
authors.affiliation: REQUIMTE, Departamento de Química-Física, Faculdade de Farmácia, Universidade do Porto, Rua-Aníbal-Cunha 164, 4099-030 Porto, Portugal. Electronic address: jrssantos@ff.up.pt.
authors.forename: J Rodrigo
authors.initials: JR
authors.lastname: Santos
authors.affiliation: REQUIMTE, Departamento de Química-Física, Faculdade de Farmácia, Universidade do Porto, Rua-Aníbal-Cunha 164, 4099-030 Porto, Portugal. Electronic address: limajlfc@ff.up.pt.
authors.forename: José L F C
authors.initials: JLFC
authors.lastname: Lima
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004008:Diclofenac / Q000032:analysis*; D004563:Electrochemistry; D004566:Electrodes; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods; D004364:Pharmaceutical Preparations / Q000592:standards*
chemical_list: D004364:Pharmaceutical Preparations; D004008:Diclofenac; D001729:Bismuth