An embodiment provides a method for measuring total chlorine in a seawater sample, including: preparing a thiocarbamate-based indicator; introducing the thiocarbamate-based indicator to a seawater sample, wherein the seawater sample contains an amount of total chlorine; adding an additive to the seawater sample, wherein the additive accelerates the reaction rate between the thiocarbamate-based indicator and total chlorine and causes a change in fluorescence of the seawater sample; and measuring the amount of total chlorine in the seawater sample by measuring an intensity of the fluorescence. Other aspects are described and claimed.

The present disclosure relates to an amperometric sensor for measuring free chlorine, which sensor comprises:

an elongate body with a tip, wherein the circumferential surface of the body constitutes a counter electrode;

a reference electrode having a silver/silverchloride electrode surface arranged on the tip of the elongate body; and

a working electrode having a gold electrode surface arranged on the tip of the elongate body wherein the gold electrode surface is composed out of a string of electrically connected, spaced apart surface parts.

An embodiment provides a method for measuring nitrate in an aqueous sample, including: introducing an aqueous sample containing an amount of nitrate to a cation exchange resin; flowing the aqueous sample over copper metal; adding a reducing reagent to the aqueous sample; adding a colorimetric indicator to the aqueous sample; and measuring the amount of nitrate in the aqueous sample by measuring a change in intensity of the absorbance. Other aspects are described and claimed.

This disclosure relates to improved devices, systems and methods for detecting and measuring oxidizing compounds in test fluids. Certain embodiments include a measurement device configured to apply a constant current to the test fluid and measure a reference voltage indicating an electrochemical potential at which electrolysis occurs in the test fluid. The measurement device is further configured to measure a second voltage indicating an oxidizing potential of the test fluid, and to calculate an oxidizer concentration measurement indicating the concentration of the oxidizing compound in the test fluid based on a voltage difference between the reference voltage and the second voltage.

A sensing platform for continuous water resource monitoring by electrochemical detection and solution parameter correction is provided. The sensing platform employs a solid-state electrolyte three-electrode cell, creating a high ionic strength environment within the solid-state electrolyte membrane, which is in ion exchange equilibria with the sampled solution. This device may be used as a standalone sensor in environments where the water parameters (pH temperature, and ionic strength) are controlled, or in concert with compensation sensors where water parameters are not controlled.

A monitor and indicator system includes a sensor part, a control and indication part, and a power part. The monitor and indicator system is configured to: (a) monitor a concentration of a sterilant in a sanitizing solution; (b) determine a depletion of the sterilant upon detecting that the concentration of the sterilant becomes equal to or falls below a predetermined threshold concentration level; and (c) indicate the depletion of the sterilant of the sanitizing solution by emitting a notification.

Measurement devices can be used for identifying concentration of arsenic species in water samples. The measurement devices can take the form of test strips including a substrate with at least one testing region that includes an amount of a testing medium. The silver reagent includes a polymer framework and a silver component that is stabilized by the framework, yet remains reactive enough to function as a colorimetric sensor for arsenic, e.g., ((Ag(H.sub.2btc))(Ag.sub.2(Hbtc))).sub.n. The initially substantially colorless testing medium exhibits a color change response when exposed to arsenic species, e.g., arsine, generated from samples including as little as 5 ppb arsenic, with an increasingly dark color as the concentration of arsenic is increased. Test strips fabricated with the silver coordination polymer display robust stability towards both light and water, allowing for an alternative to mercury-based field test kits in real-world field tests under direct sunlight and high humidity conditions.

The present application relates to a method for improving analytical efficiency and cost effectiveness of oxygen isotope analysis of an aqueous sample. In particular, the present application relates to a method of determining an oxygen isotope composition of an aqueous sample by (a) equilibrating the aqueous sample with CO.sub.2 gas wherein the aqueous sample comprises an effective amount of carbonic anhydrase (CA) enzyme; and (b) measuring the oxygen isotope composition of the CO.sub.2 at equilibrium, wherein the oxygen isotope composition of the CO.sub.2 corresponds to the oxygen isotope composition of the aqueous sample.

A liquid quality measurement apparatus includes a piping constituting a circulation path through which a measurement liquid flows, and a liquid quality sensor for measuring the quality of the measurement liquid, and an addition tank connected to the piping via an inlet port and an outlet port. The addition tank has an internal space, an introduction portion through which a liquid different from the measurement liquid is introduced, and a ventilation portion through which air is released from the internal space to the outside. An addition tank internal channel is formed at a bottom portion of the internal space. The addition tank internal channel connects the inlet port and the outlet port. The measurement liquid flows through the addition tank internal channel. The introduction portion and the ventilation portion are disposed in a wall surface of the addition tank that faces the internal space above the addition tank internal channel.

Disclosed is a method for quantification of water and/or one or more ionic liquid components in an ionic liquid (IL)/water (H2O) mixture. The method includes obtaining one or more Raman spectra for the IL/H2O mixture, and using a quantitative calibration model with the one or more Raman spectra to quantify water and/or one or more ionic liquid components in the IL/H2O mixture.