Optimising amperometric pH sensing in blood samples: an iridium oxide electrode for blood pH sensing.

Amperometric pH sensing in blood samples has been studied using iridium oxide electrodes. The iridium oxide electrodes are made by electrodeposition of iridium oxide onto an iridium micro-disc electrode from an alkaline solution of iridium(iii) oxide. The response of the electrode is studied in aqueous solutions and authentic samples of sheep's blood employing both cyclic voltammetry and square wave voltammetry. Uncertainties of pH measurement in blood samples via cyclic voltammetry (±0.07 pH units) were improved by a factor of two using square wave voltammetry (±0.03 pH units). Limitations of amperometric pH sensing in blood samples are considered as caused by the uncertainty of the required reference measurements (via a conventional glass electrode) and also the use of matrix-free and low ionic strength buffers to calibrate a standard glass electrode for the measurement of blood pH.

[1]  B. B. Owen,et al.  The Physical Chemistry of Electrolytic Solutions , 1963 .

[2]  R. Robinson,et al.  References standards for the electrometric determination, with ion-selective electrodes, of potassium and calcium in blood serum. , 1975, Analytica chimica acta.

[3]  X.-J. Gao,et al.  Plaque pH and Associated Parameters in Relation to Caries , 1999, Caries Research.

[4]  K. Yamanaka.  Anodically Electrodeposited Iridium Oxide Films (AEIROF) from Alkaline Solutions for Electrochromic Display Devices , 1989 .

[5]  M. Hitchman,et al.  Evaluation of iridium oxide electrodes formed by potential cycling as pH probes. , 1988, The Analyst.

[6]  M. Hitchman,et al.  Considerations of the pH dependence of hydrous oxide films formed on iridium by voltammetric cycling , 1992 .

[7]  Rossana E. Madrid,et al.  Potentiometric textile-based pH sensor , 2018 .

[8]  Ivo Leito,et al.  Estimation of uncertainty in routine pH measurement , 2002 .

[9]  W. Cascio,et al.  Electrodeposited iridium oxide pH electrode for measurement of extracellular myocardial acidosis during acute ischemia. , 1998, Analytical chemistry.

[10]  D. Connelly,et al.  Seawater-pH measurements for ocean-acidification observations , 2012 .

[11]  R. D. Levie,et al.  A pH centenary , 2014 .

[12]  Jongman Park,et al.  Surface renewable nano-iridium oxide polymeric composite pH electrodes , 2014 .

[13]  Hung Cao,et al.  Sol-Gel Deposition of Iridium Oxide for Biomedical Micro-Devices , 2015, Sensors.

[14]  R. Compton,et al.  The effect of insulator nano-sheath thickness on the steady state current at a micro-disc electrode , 2015 .

[15]  A. Salimi,et al.  Boron doped diamond electrode modified with iridium oxide for amperometic detection of ultra trace amounts of arsenic(III) , 2004 .

[16]  PREPARATION OF AN OXIDIZED IRIDIUM ELECTRODE AND THE VARIATION OF ITS POTENTIAL WITH PH , 1984 .

[17]  P. Spitzer,et al.  Measurement of pH. Definition, standards, and procedures (IUPAC Recommendations 2002) , 2002 .

[18]  D. Fraenkel.  Monoprotic mineral acids analyzed by the smaller-ion shell model of strong electrolyte solutions. , 2011, The journal of physical chemistry. B.

[19]  Yoshiyuki Sato,et al.  Electrochromism in Iridium Oxide Films Prepared by Thermal Oxidation of Iridium‐Carbon Composite Films , 1987 .

[20]  D. Fraenkel.  Simplified electrostatic model for the thermodynamic excess potentials of binary strong electrolyte solutions with size-dissimilar ions , 2010 .

[21]  Wouter Olthuis,et al.  pH sensor properties of electrochemically grown iridium oxide , 1990 .

[22]  E. O'Sullivan,et al.  Influence of hydrolysis on the redox behaviour of hydrous oxide films , 1981 .

[23]  Mu Chiao,et al.  A flexible pH sensor based on the iridium oxide sensing film , 2011 .

[24]  Z. Lewandowski,et al.  Iridium oxide pH microelectrode , 1992, Biotechnology and bioengineering.

[25]  Susan Carroll,et al.  Self-calibrating microfabricated iridium oxide pH electrode array for remote monitoring. , 2010, Analytical chemistry.

[26]  Michael J. Tarlov,et al.  Mechanistic and response studies of iridium oxide pH sensors , 1990 .

[27]  J. Baur,et al.  Electrochemical deposition of iridium (IV) oxide from alkaline solutions of iridium(III) oxide , 1998 .

[28]  A. Bollini,et al.  Red blood cell shape as a function of medium's ionic strength and pH. , 1998, Biochimica et biophysica acta.

[29]  T. Kakiuchi,et al.  Determination of single-ion activities of H+ and Cl- in aqueous hydrochloric acid solutions by use of an ionic liquid salt bridge. , 2011, The journal of physical chemistry. B.

[30]  M. Hitchman,et al.  A field-induced poising technique for promoting convergence of standard electrode potential values of thermally oxidized iridium pH sensors. , 1992, Talanta.

[31]  R. Robinson,et al.  Ionic hydration and activity in electrolyte solutions. , 1948, Journal of the American Chemical Society.

[32]  R. Bates,et al.  Ionic hydration and single ion activities in unassociated chlorides at high ionic strengths , 1970 .

[33]  Robert J. Gillies,et al.  Tumor pH and Its Measurement , 2010, The Journal of Nuclear Medicine.

[34]  Tian C Zhang,et al.  Fabrication of anodically electrodeposited iridium oxide film pH microelectrodes for microenvironmental studies. , 2002, Analytical chemistry.

[35]  S. Ardizzone,et al.  Properties of thermally prepared iridium dioxide electrodes , 1981 .

[36]  Sheng Yao,et al.  A long-term stable iridium oxide pH electrode , 2002 .

[37]  G. Meinrath,et al.  Uncertainties in Determination of pH , 2000 .

[38]  Marcin Majda,et al.  Effects of Electrodeposition Conditions and Protocol on the Properties of Iridium Oxide pH Sensor Electrodes , 2009 .

[39]  Marc Madou,et al.  A pH Electrode Based on Melt-Oxidized Iridium Oxide , 2001 .

[40]  Danny O'Hare,et al.  An iridium oxide microelectrode for monitoring acute local pH changes of endothelial cells. , 2015, The Analyst.

[41]  P. Bergveld,et al.  Preparation of iridium oxide and its application in sensor-actuator systems , 1991 .