title: A SO2-selective electrode based on a Zn-porphyrin for wine analysis.
abstract: This work describes the assessment of a SO2-selective electrode based on the use of the neutral carrier 5,10,15,20-tetraphenyl(porphyrinate)zinc(II) in a PVC membrane plasticized with 2-nitrophenyl phenyl ether. After being conditioned in 2 mol L(-1) diethylamine solution for 24 h, the electrode exhibited selective anionic response toward the analyte in a concentration interval of more than four decades, with an slope of -59.5 mV dec(-1), a practical detection limit of 3.7×10(-6) mol L(-1) and a low limit of linear range of 7.2×10(-6) mol L(-1). The response mechanism is based on the displacement of the diethylamine:metalloporphyrin complex equilibrium within membrane bulk, inducing a variation in the cationic-sites to ionophore ratio. In turn, free hydroxyl ions are complexed by the displaced ionophore in a ratio 1:1 and translated as single negative charge nernstian response. Finally, the selectivity of the electrode is evaluated in view of its application to wine analysis. Results had high accuracy and precision when compared with a reference method.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia, Murcia, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Cuartero
authors.forename: Célia G
authors.initials: CG
authors.lastname: Amorim
authors.forename: Alberto N
authors.initials: AN
authors.lastname: Araújo
authors.forename: Joaquín A
authors.initials: JA
authors.lastname: Ortuño
authors.forename: Maria C B S M
authors.initials: MC
authors.lastname: Montenegro
mesh_terms: D017736:Ion-Selective Electrodes; D008665:Metalloporphyrins / Q000737:chemistry*; D013458:Sulfur Dioxide / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
chemical_list: D008665:Metalloporphyrins; D013458:Sulfur Dioxide; C017802:zinc hematoporphyrin
keywords: Ion-selective electrodes; Metalloporphyrins; Potentiometry; Sulfur dioxide; Wine analysis