Electrochemical pH measurement
First Claim
1. A method of measuring the pH of an aqueous liquid, comprisingexposing the aqueous liquid comprising buffer at a concentration of 0.01 molar or less to an electrochemical sensor comprising an electrode with a redox active compound immobilized to the electrode with at least one functional group convertible electrochemically between reduced and oxidized forms upon transfer of at least one proton between the compound and surrounding aqueous phase,wherein the reduced form of the redox active compound incorporates a partial structure,
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Abstract
A method of measuring pH of aqueous liquid with little or no buffer present uses an electrochemical pH sensor which comprises a plurality of electrodes with a redox active organic compound attached to an electrode and having at least one functional group convertible electrochemically between reduced and oxidized forms with transfer of at least one proton between the compound and surrounding aqueous phase, wherein the compound has at least one substituent group which promotes hydrogen bonding at a said functional group and thereby increases the reaction rate of proton transfer. The substituent group may form an internal hydrogen bond with a redox-convertible group or may enhance polarity to promote electrostatic interaction with water molecules and reduce activation energy. Such an electrochemical sensor may be used for pH measurement in computer controlled equipment for processing an aqueous liquid.
17 Citations
11 Claims
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1. A method of measuring the pH of an aqueous liquid, comprising
exposing the aqueous liquid comprising buffer at a concentration of 0.01 molar or less to an electrochemical sensor comprising an electrode with a redox active compound immobilized to the electrode with at least one functional group convertible electrochemically between reduced and oxidized forms upon transfer of at least one proton between the compound and surrounding aqueous phase, wherein the reduced form of the redox active compound incorporates a partial structure,
Specification