Graphite Screen-Printed Electrodes Applied for the Accurate and Reagentless Sensing of pH

Author(s)

Galdino, Flavia E. ^{[1, 2]} ; Smith, Jamie P. ^[2] ; Kwamou, Sophie I. ^[3] ; Kampouris, Dimitrios K. ^[2] ; Iniesta, Jesus ^{[4, 5]} ; Smith, Graham C. ^[6] ; Bonacin, Juliano A. ^[1] ; Banks, Craig E. ^[2]

Affiliation

^[1] Univ Campinas UNICAMP, Inst Chem, BR-13083970 Campinas, SP - Brazil

^[2] Manchester Metropolitan Univ, Fac Sci & Engn, Sch Sci & Environm, Div Chem & Environm Sci, Manchester M1 5GD, Lancs - England

^[3] Univ Paris 12, Fac Sci & Technol, F-94010 Creteil - France

^[4] Univ Alicante, Dept Phys Chem, Alicante 03690 - Spain

^[5] Univ Alicante, Inst Electrochem, Alicante 03690 - Spain

^[6] Univ Chester, Fac Sci & Engn, Dept Nat Sci, Chester CH2 4NU, Cheshire - England

• Document type: Journal article
• Source: Analytical Chemistry; v. 87, n. 23, p. 11666-11672, DEC 1 2015.
• Web of Science Citations: 13

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. (AU)

• FAPESP's process: 14/07705-2 - Graphene functionalized architectures: surface modification of graphene from gold nanoparticles and iron complex
• Grantee: Flávia Elisa Galdino
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation