Patent ID: 9244034
Filing Date: 2016-01-26
CPC Classification: G01N

Claim Text:
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, wherein the oxidized form of the redox active compound incorporates a partial structure, where the carbon atoms are joined by conjugated bonds in both the reduced form and the oxidized form of the redox active compound, wherein the compound has at least one keto group, which is positioned to participate in internal hydrogen bonding with the at least one functional group in its reduced form and increases the reaction rate of proton transfer by reducing the activation energy for transfer of a proton and/or promoting hydrogen bonding at a said functional group, and observing the redox reaction at the electrochemical sensor.