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Sensitivities of Key Parameters in the Preparation of Silver/Silver Chloride Electrodes Used in Harned Cell Measurements of pH

1
Analytical Science Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, UK
2
Department of Biomedical and Inorganic Chemistry, Laboratoire National de Métrologie et d’Essais, 1 rue G. Boissier, 75015 Paris, France
*
Author to whom correspondence should be addressed.
Sensors 2011, 11(8), 8072-8084; https://doi.org/10.3390/s110808072
Received: 24 June 2011 / Revised: 15 August 2011 / Accepted: 16 August 2011 / Published: 17 August 2011
(This article belongs to the Section Chemical Sensors)
A questionnaire was completed by fourteen world leading national metrology institutes to study the influence of several variables in the preparation of Ag/AgCl electrodes on the accuracy of Harned cell measurements of pH. The performance of each institute in the last decade has been assessed based on their results in eight key comparisons, organized by the Bureau International des Poids et Measures Consultative Committee for Amount of Substance, involving the measurement of pH of phosphate, phthalate, carbonate, borate and tetroxalate buffer solutions. The performance of each laboratory has been correlated to the results of the questionnaire to determine the critical parameters in the preparation of Ag/AgCl electrodes and their sensitivities with respect to the accuracy of pH measurement. This study reveals that the parameters most closely correlated to performance in comparisons are area of electrode wire exposed to the electrolyte, diameter and porosity of the Ag sphere prior to anodisation, amount of Ag converted to AgCl during anodisation, stability times employed for electrodes to reach equilibrium in solution prior to measurement, electrode rejection criteria employed and purity of reagents. View Full-Text
Keywords: pH; Harned cell; Ag/AgCl electrode; primary methods pH; Harned cell; Ag/AgCl electrode; primary methods
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MDPI and ACS Style

Brewer, P.J.; Stoica, D.; Brown, R.J.C. Sensitivities of Key Parameters in the Preparation of Silver/Silver Chloride Electrodes Used in Harned Cell Measurements of pH. Sensors 2011, 11, 8072-8084.

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