Method and compositions using transition metal salts and/or ammonium chloride to liberate toxins and other molecules from cyanobacteria, useful for assaying for total cyanobacterial toxins in lakes, reservoirs and other waters.

Methods, apparatus and compositions are described for the measurement of metal and/or metalloid elements, including selenium in samples. More specifically, the present disclosure provides a sensor and/or array of sensors to measure metal and/or metalloid analytes, e.g., sensor and/or array of sensors having a chelator molecule, the chelator molecule including a peptide.

A pool maintenance system that includes a spectroscopic device that is configured to analyze a fluid of a pool.

The system for determining chlorine demand in water includes a reagent supply tank configured for holding a solution of sodium hypochlorite of known concentration, a buffer tank positioned in fluid communication with the reagent supply tank, the buffer tank including a first conduit configured for transferring the solution from the reagent supply tank into the buffer tank, and a mixing tank positioned in fluid communication with the buffer tank, the mixing tank including a second conduit configured for transferring the solution from the buffer tank into the mixing tank to form a composite solution. The system further includes a first chlorine measuring device for measuring the free chlorine residual in a water source connected to the mixing tank, a second chlorine measuring device configured for measuring the free chlorine residual in the composite solution, and a pump operatively coupled to the water source.

Fire present invention relates to new electrochemical probes for the measure of an analyte selected from the group consisting of: free chlorine, chlorine dioxide, total chlorine and peracetic acid; characterized in that said probe includes at least a printed electrode nano- or micro-structured whit a nano- or micromaterial selected from the group consisting of: nano- or microparticies of carbon black and/or nano- or microparticles of a metal selected from the group consisting of gold, silver, platinum, copper and combinations or alloys thereof.

A method for detecting for the presence of H.sub.2S or HS.sup.− anion in a system, comprising contacting a sample from the system with a compound, or a protonate or salt thereof, having a structure represented by:

##STR00001## wherein Y represents an aromatic group or a substituted aromatic group; n is 1 or 2; R is independently H, alkyl, substituted alkyl, a polyether moiety, carboxyl, substituted carboxyl, carbamate, substituted carbonate, carbonyloxy, alkoxy, substituted alkoxy, haloalkyl, halogen, nitro, amino, amido, aryloxy, cyano, hydroxyl, or sulfonyl; R.sup.1 is H, substituted lower alkyl, lower alkyl, substituted aralkyl or aralkyl; R.sup.2 is selected from H, acyl, substituted aralkyl, aralkyl, phosphonyl, —SO.sub.2R.sup.3; —C(O)R.sup.5; —C(O)OR.sup.7 or —C(O)NR.sup.9R.sup.10; R.sup.3; R.sup.5; R.sup.7; R.sup.9 and R.sup.10 are each independently selected from H, substituted lower alkyl, lower alkyl, substituted aralkyl, aralkyl, substituted aryl or aryl.

A liquid sampling device for use with a mobile device comprises a wired connection for connecting the liquid sampling device to the mobile device, a sample receiving and testing section capable of receiving a liquid sample and conducting electrochemical testing of the liquid sample and a sample testing circuit configured to communicate at least one liquid sample test result to the mobile device via the wired connection. Associated methods and a mobile device application for interfacing with the liquid sampling device are also disclosed.

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.

The amount of sulfite in water can be determined using fluorescence by adding to the water a fluorophore compound, measuring a fluorescence signal of the water, and determining the amount of the sulfite in the water based on the measured fluorescence signal. This method can be used in a water treatment system in which a sulfite solution is added to treat the water, and the amount of sulfite that is added can be controlled based on the measured fluorescence of the water.

A computing system is designed for measuring the A.sup.2/O effluent total phosphorus based on data-driven method. Several related variables are obtained by analyzing the relationship between effluent total phosphorus and other process variables. In addition, a hardware platform is designed and built to further analysis sample information of each variable. Finally, the computing system for measuring total phosphorus in effluent is developed by combining the hardware and software as provided in implementations herein.