title: Graphite Screen-Printed Electrodes Applied for the Accurate and Reagentless Sensing of pH.
abstract: A reagentless pH sensor based upon disposable and economical graphite screen-printed electrodes (GSPEs) is demonstrated for the first time. The voltammetric pH sensor utilizes GSPEs which are chemically pretreated to form surface immobilized oxygenated species that, when their redox behavior is monitored, give a Nernstian response over a large pH range (1-13). An excellent experimental correlation is observed between the voltammetric potential and pH over the entire pH range of 1-13 providing a simple approach with which to monitor solution pH. Such a linear response over this dynamic pH range is not usually expected but rather deviation from linearity is encountered at alkaline pH values; absence of this has previously been attributed to a change in the pKa value of surface immobilized groups from that of solution phase species. This non-deviation, which is observed here in the case of our facile produced reagentless pH sensor and also reported in the literature for pH sensitive compounds immobilized upon carbon electrodes/surfaces, where a linear response is observed over the entire pH range, is explained alternatively for the first time. The performance of the GSPE pH sensor is also directly compared with a glass pH probe and applied to the measurement of pH in "real" unbuffered samples where an excellent correlation between the two protocols is observed validating the proposed GSPE pH sensor.
authors.affiliation: Institute of Chemistry, University of Campinas-UNICAMP , P.O. Box 6154, 13083-970, Campinas, São Paulo Brazil.|Faculty of Science and Engineering, School of Science and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University , Chester Street, Manchester M1 5GD, U.K.
authors.forename: Flávia E
authors.initials: FE
authors.lastname: Galdino
authors.affiliation: Faculty of Science and Engineering, School of Science and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University , Chester Street, Manchester M1 5GD, U.K.
authors.forename: Jamie P
authors.initials: JP
authors.lastname: Smith
authors.affiliation: Université Paris-Est Créteil-Val de Marne , Faculté des Sciences et Technologie, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex France.
authors.forename: Sophie I
authors.initials: SI
authors.lastname: Kwamou
authors.affiliation: Faculty of Science and Engineering, School of Science and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University , Chester Street, Manchester M1 5GD, U.K.
authors.forename: Dimitrios K
authors.initials: DK
authors.lastname: Kampouris
authors.affiliation: Physical Chemistry Department and Institute of Electrochemistry, University of Alicante ,03690, San Vicente del Raspeig, Alicante Spain.
authors.forename: Jesus
authors.initials: J
authors.lastname: Iniesta
authors.affiliation: Faculty of Science and Engineering, Department of Natural Sciences, University of Chester Thornton Science Park, Pool Lane, Ince, Chester CH2 4NU, U.K.
authors.forename: Graham C
authors.initials: GC
authors.lastname: Smith
authors.affiliation: Institute of Chemistry, University of Campinas-UNICAMP , P.O. Box 6154, 13083-970, Campinas, São Paulo Brazil.
authors.forename: Juliano A
authors.initials: JA
authors.lastname: Bonacin
authors.affiliation: Faculty of Science and Engineering, School of Science and the Environment, Division of Chemistry and Environmental Science, Manchester Metropolitan University , Chester Street, Manchester M1 5GD, U.K.
authors.forename: Craig E
authors.initials: CE
authors.lastname: Banks