Methods, electrodes, and sensors for chlorine species sensing using pseudo-graphite are disclosed. In one illustrative embodiment, a method may include coating a pseudo-graphite material onto a surface of an electrode substrate to produce a pseudo-graphite surface. The method may also include exposing the pseudo-graphite surface to a sample to detect chlorine species in the sample.

[Problem] To provide a system for inference of a measurement target dynamic state, the system being capable of providing not only information as to whether a culture solution is aerobic or anaerobic, but also data for determining a culture operation and for optimizing various conditions of the culture solution. [Solution] A system for inference of a measurement target dynamic state, comprising: a reference electrode; a first working electrode; a second working electrode of which at least the material or surface treatment is different from the first working electrode; a third working electrode of which at least the material or surface treatment is different from the first working electrode and the second working electrode; and an information storage unit which receives first potential information relating to the redox potential between the reference electrode and the first working electrode, second potential information relating to the redox potential between the reference electrode and the second working electrode, and third potential information relating to the redox potential between the reference electrode and the third working electrode, and stores information including the first potential information, the second potential information, and the third potential information.

Various apparatus, systems, and methods for measuring a solution characteristic of a sample comprising microorganisms are disclosed. In one embodiment, a sensor apparatus is disclosed comprising a sample container comprising a sample chamber configured to receive the sample and a reference sensor component comprising a reference conduit having a reference conduit cavity defined therein. The reference conduit cavity can be at least partially filled with a reference buffer gel, buffer solution, or wicking component. A segment of the reference conduit can extend into the sample chamber. A reference electrode material can be positioned at a proximal end of the wicking component or extend partially into the reference conduit cavity. The sensor apparatus can also comprise an active sensor component having an active electrode in fluid contact with the sample. The sample in the sample chamber can be aerated through an aeration port defined along a surface of the sample container.

A sensing electrode includes a first electrode assembly, a second electrode assembly and a sealing component. The first electrode assembly includes an inner tubular body and a reference electrode component installed in the inner tubular body. The second electrode assembly includes an outer tubular body and a working electrode component installed in the outer tubular body. The first electrode assembly is installed in the outer tubular body. The sealing component is located between the inner and outer tubular bodies and provided to inhibit infiltration of an etching solution into the outer tubular body and leakage of an electrolyte from the inner tubular body. Thus, the sensing electrode has a better stability and service life.

Methods for in situ measurement of an oxidation reduction potential (ORP) and pH of a solution comprising iron are provided. The methods comprise measuring a kinetic parameter at an electrode surface of an electrode system comprising a working electrode, a counter electrode and a pseudo-reference electrode, wherein the kinetic parameter is associated with ferric reduction or both ferric reduction and ferrous oxidation and comparing the kinetic parameter to calibration data for the electrode system to determine the ORP and pH of the solution. Also provided are apparatus and systems for in situ measurement of an ORP and pH of a solution comprising iron. The apparatus and systems comprise an electrode system comprising a working electrode, a counter electrode and a pseudo-reference electrode and a detector for measuring a kinetic parameter at an electrode surface of the electrode system.

System (100) and method of automatically controlling an active oxidant concentration (e.g. sodium hypochlorite) for a process of producing monochloramine comprising applying metered amounts of an oxidant solution and an amine solution to a defined area (114). An electrochemical measurement device is provided in association with the oxidant solution and prior to the defined area, N comprising at least first and second electrodes and an output terminal. A predetermined voltage potential is applied across the first and second electrodes, wherein an obtained amperometric measurement corresponds to a real-time concentration of the active oxidant in the oxidant solution. A feedback signal is generated based on the obtained measurement via the output terminal to a controller (108), which automatically regulates, in real-time and based at least in part on the control signal, the metered amount of oxidant solution provided to the defined area.

A method in which a concentration of a chemical species of interest is obtained. The method comprises measuring a property (e.g. the oxidation reduction potential) of a reagent (typically based on a simple single electron redox couple) to obtain a baseline measurement. The reagent is mixed with the solution under test, then the property of the mixture is measured to obtain a post reaction measurement. Then the concentration of the chemical species of interest is determined based on the baseline measurement and the first post reaction measurement, typically by calculating a difference of the baseline measurement and the post reaction measurement, then using the difference and a pre-determined conversion table to determine the concentration of the chemical species of interest.

A method for controlling the catalytic oxidation of cellulose includes using a heterocyclic nitroxyl compound as catalyst oxidizing cellulose in a reaction mixture comprising liquid medium, the catalyst and hypochlorite as main oxidant analyzing one or more oxidative chlorine species dependent on the hypochlorite concentration of the reaction mixture on line in the reaction mixture or in a gas composition which is in contact with the reaction mixture; and controlling supply of hypochlorite to the reaction mixture on the basis of the analysis.

A sensor including first and second electrodes can be used to determine the concentration of at least one chemical constituent in a fluid sample under test. The electrodes can be disposed in the fluid sample and a predetermined voltage can be applied to a first electrode. The voltage can cause a current to flow between the first and second electrodes through the sample, the current dependent on the concentration of the chemical constituent in the fluid sample. A sense resistor is coupled to the first electrode such that the current flowing between the electrodes flows through the sense resistor. A processor electrically isolated from the electrodes can receive data signals indicative of the voltage drop across the sense resistor and the voltage applied at the first electrode. The received signals can be used to determine the concentration of the constituent in the fluid sample.

An ion sensor apparatus comprises at least one ion sensitive field effect transistor (ISFET) device configured to be exposed to a liquid, a reference electrode configured to contact the liquid to which the ISFET device is exposed, and at least one magnet configured to intermittently expose the ISFET device to a magnetic field. A processor is operatively connected to the ISFET device and the reference electrode. The processor modulates the magnetic field to produce a corresponding modulated output in resistance of the ISFET device, and modulation of a reported output value of the ion sensor apparatus.