The present invention appropriately determines a time to replace a responsive glass membrane for measuring a sample containing hydrofluoric acid. A measurement device for measuring a hydrogen ion concentration of a liquid sample containing hydrofluoric acid, the measurement device including a glass electrode that measures a hydrogen ion concentration in the liquid sample, the glass electrode including a responsive glass membrane, a membrane resistance measurement unit that measures a membrane resistance value of the responsive glass membrane, a temperature measurement unit that measures a temperature of an environment in which the responsive glass membrane is disposed, and an output unit that outputs a replacement index for replacing the responsive glass membrane based on the membrane resistance value and the temperature.

The present invention appropriately determines a time to replace a responsive glass membrane for measuring a sample containing hydrofluoric acid. A measurement device for measuring a hydrogen ion concentration of a liquid sample containing hydrofluoric acid, the measurement device including a glass electrode that measures a hydrogen ion concentration in the liquid sample, the glass electrode including a responsive glass membrane, a membrane resistance measurement unit that measures a membrane resistance value of the responsive glass membrane, a temperature measurement unit that measures a temperature of an environment in which the responsive glass membrane is disposed, and an output unit that outputs a replacement index for replacing the responsive glass membrane based on the membrane resistance value and the temperature.

Embodiments of the invention are directed to a system for detecting neurotransmitters. A non-limiting example of the system includes a porous electrode. A system can also include a pH sensor attached to the porous electrode, wherein the pH sensor includes a sensing electrode and a reference electrode. The system can also include electronic circuitry in communication with the pH sensor.

Embodiments of the invention are directed to a system for detecting neurotransmitters. A non-limiting example of the system includes a porous electrode. A system can also include a pH sensor attached to the porous electrode, wherein the pH sensor includes a sensing electrode and a reference electrode. The system can also include electronic circuitry in communication with the pH sensor.

An online calibration system for an electrochemical sensor. The calibration system comprises a calibration electrode coupled with a redox species, where the redox species is configured to control a pH of a reference solution local to the calibration electrode, such that when a voltammetric signal is applied to the calibration electrode the output generated from the calibration system is determined by the local environment pH. The output signal from the calibration system is used to calibrate a reference potential generated by a reference system of the electrochemical sensor to correct for drift in the reference potential when the electrochemical sensor is being used. The calibration electrode may be disposed in a reference cell of the electrochemical sensor.

An online calibration system for an electrochemical sensor. The calibration system comprises a calibration electrode coupled with a redox species, where the redox species is configured to control a pH of a reference solution local to the calibration electrode, such that when a voltammetric signal is applied to the calibration electrode the output generated from the calibration system is determined by the local environment pH. The output signal from the calibration system is used to calibrate a reference potential generated by a reference system of the electrochemical sensor to correct for drift in the reference potential when the electrochemical sensor is being used. The calibration electrode may be disposed in a reference cell of the electrochemical sensor.

A measuring element is disclosed for an ion-sensitive solid-contact electrode for measuring ion activity in a measurement medium. An ion-sensitive solid-contact electrode having such a measuring element and an electrochemical sensor having such a solid-contact electrode are also disclosed. The measuring element can include an ion-sensitive layer arranged to contact a measurement medium when in operation, and conductive to lithium ions; and a single-phase electrically conductive layer, which includes metallic lithium or a lithium-(0)-alloy. A solid-state electrolyte layer can be arranged between the ion-sensitive layer and the electrically conductive layer.

A measuring element is disclosed for an ion-sensitive solid-contact electrode for measuring ion activity in a measurement medium. An ion-sensitive solid-contact electrode having such a measuring element and an electrochemical sensor having such a solid-contact electrode are also disclosed. The measuring element can include an ion-sensitive layer arranged to contact a measurement medium when in operation, and conductive to lithium ions; and a single-phase electrically conductive layer, which includes metallic lithium or a lithium-(0)-alloy. A solid-state electrolyte layer can be arranged between the ion-sensitive layer and the electrically conductive layer.

A simplified, rigorous and accurate method of measuring pH of an analyte solution with extreme precision, which does not cause errors against actual pH through compensating a pH variation by a liquid temperature or a concentration of potassium chloride of an internal liquid in a glass electrode or a reference electrode when pH is measured with respect to various analyte solutions such as a sample solution having a high concentration of salts, a sample solution contaminated with salts and a sample solution having a low concentration of salts.

A simplified, rigorous and accurate method of measuring pH of an analyte solution with extreme precision, which does not cause errors against actual pH through compensating a pH variation by a liquid temperature or a concentration of potassium chloride of an internal liquid in a glass electrode or a reference electrode when pH is measured with respect to various analyte solutions such as a sample solution having a high concentration of salts, a sample solution contaminated with salts and a sample solution having a low concentration of salts.