title: Direct determination of copper in urine using a sol-gel optical sensor coupled to a multicommutated flow system.
abstract: In this work, a multicommutated flow system incorporating a sol-gel optical sensor is proposed for direct spectrophotometric determination of Cu(II) in urine. The optical sensor was developed by physical entrapment of 4-(2-pyridylazo)resorcinol (PAR) in sol-gel thin films by means of a base-catalysed process. The immobilised PAR formed a red 2:1 complex with Cu(II) with maximum absorbance at 500 nm. Optical transduction was based on a dual-colour light-emitting diode (LED) (green/red) light source and a photodiode detector. The sensor had optimum response and good selectivity towards Cu(II) at pH 7.0 and its regeneration was accomplished with picolinic acid. Linear response was obtained for Cu(II) concentrations between 5.0 and 80.0 microg L(-1), with a detection limit of 3.0 microg L(-1) and sampling frequency of 14 samples h(-1). Interference from foreign ions was studied at a 10:1 ( w/ w) ion:Cu(II) ratio. Results obtained from analysis of urine samples were in very good agreement with those obtained by inductively coupled plasma mass spectrometry (ICP-MS); there was no significant differences at a confidence level of 95%.
authors.affiliation: REQUIMTE/Departamento de Química-Física, Faculdade de Farmácia, Universidade do Porto, R. Aníbal Cunha 164, 4099-030, Porto, Portugal.
authors.forename: Paula C A
authors.initials: PC
authors.lastname: Jerónimo
authors.forename: Alberto N
authors.initials: AN
authors.lastname: Araújo
authors.forename: M Conceição B S M
authors.initials: MC
authors.lastname: Montenegro
authors.forename: Celio
authors.initials: C
authors.lastname: Pasquini
authors.forename: Ivo M
authors.initials: IM
authors.lastname: Raimundo
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002384:Catalysis; D003300:Copper / Q000652:urine*; D005782:Gels; D006801:Humans; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry / Q000379:methods; D008567:Membranes, Artificial; D055095:Optics and Photonics / Q000295:instrumentation*; D010316:Particle Size; D016062:Porosity; D012118:Resorcinols / Q000737:chemistry; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013997:Time Factors
chemical_list: D005782:Gels; D008567:Membranes, Artificial; D012118:Resorcinols; D003300:Copper; C028398:4-(2-pyridylazo)resorcinol