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 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 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.

The present invention provides a method for the rapid monitoring of biological analytes in a point-of-care setting by providing a smart phone; providing a sample chamber; providing a sample; providing a dark box with a smartphone holder attached to the dark box top with the camera opening positioned about the aperture, adding a biological specimen suspected of containing a biological analyte in the sample chamber; adding a bis(2,4,6-trichlorophenyl) oxalate, an imidazole and a fluorophore to the sample chamber to react with the biological analyte; placing the sample chamber into the dark box; generating an emission from the fluorophore in response to the reaction with the biological analyte; and recording a set of time-lapse images of the emission with the smartphone.

An electrochemical fluid sensor for a downhole production tool positionable in a wellbore penetrating a subterranean is provided. The wellbore has a downhole fluid therein. The electrochemical fluid sensor includes a sensor housing positionable in the downhole tool, a sensing solution positionable in the housing (the sensing solution including a mediator reactive to target chemicals), a gas permeable membrane to fluidly isolate the downhole fluid from the sensing solution (the gas permeable membrane permitting the passage of gas to the sensing solution), and a plurality of electrodes positioned about the housing a distance from the gas permeable membrane to measure reaction by the sensing solution whereby downhole parameters may be determined.

A hydrogen sulfide gas detector is provided. The detector includes a metal oxide semiconductor-based hydrogen sulfide gas sensor having an electrical characteristic that varies with hydrogen sulfide gas concentration. Measurement circuitry is coupled to the metal oxide semiconductor-based hydrogen sulfide gas detector to measure the electrical characteristic. A controller is coupled to the measurement circuitry and is configured to receive an indication of the electrical characteristic of the hydrogen sulfide gas sensor as well as an indication of ambient humidity. The controller is configured to provide a compensated hydrogen sulfide gas concentration output based on the indication of the electrical characteristic of the hydrogen sulfide gas sensor, an indication of ambient temperature, and the indication of ambient humidity.

Method for the detection and quantification of the H.sub.2S which measures concentration of the H.sub.2S in the drilling mud including the steps of measurement of the initial concentrations of H.sub.2S in free form and of the hydrogen sulphide HS.sup. and sulphide S.sup.2 ion species, dissolved in the sample of mud; acidification of the sample of mud, to generate gaseous H.sub.2S, making the hydrogen sulphide (HS.sup.) and sulphide (S.sup.2) ions dissolved in the mud and the H.sub.2S precipitated in solid form in the scavengers react; measuring concentration of the gaseous H.sub.2S formed following the first acidification; and relative system including at least: a mud sample collector; a unit measuring concentration of the hydrogen sulphide HS.sup. and sulphide S.sup.2 ion species in the sample; a unit for measuring concentration of the free H.sub.2S; a unit to acidify the sample of mud; electronic controller and storage and processing of the measurements made.

Processes for sensing a variety of toxic chemicals and/or processes for determining the residual life of a filter or filtration system are provided. Exemplary process for sensing a toxic chemical include contacting a toxic chemical, or byproduct thereof, with a sorbent that includes a porous metal hydroxide and a transition metal reactant suitable to react with a toxic chemical or byproduct thereof. The sorbent is contacted with the toxic chemical or byproduct thereof for a sampling time. A difference between a post-exposure colorimetric state of the sorbent and a pre-exposure colorimetric state of the sorbent or control is determined to thereby sense exposure to, or the presence of, the toxic chemical or byproduct thereof.

A device that includes a polymeric layer, wherein the polymeric layer comprises (A) a polymer and, incorporated within the polymeric layer, (B) a compound, or a protonate or salt thereof, wherein the compound, or a protonate or salt thereof, has a structure that includes at least one moiety configured for reversible, non-covalent binding of the anionic sulfide species.

A method of detecting at least one of an analyte or a condition of a fluid within a subterranean formation includes operably coupling a radiation source to at least one optical fiber coupled to a sensor having optically sensitive materials including at least one of chromophores, fluorophores, metal nanoparticles, or metal oxide nanoparticles dispersed within an optically transparent permeable matrix material. The sensor is contacted within a wellbore with a fluid and the fluid is passed through at least a portion of the sensor. Electromagnetic radiation is transmitted from the radiation source through at least one optical fiber to the sensor and at least one of an absorbance spectrum, an emission spectrum, a maximum absorption intensity, or a maximum emission intensity of electromagnetic radiation passing through the sensor after contacting at least some of the optically sensitive materials with the fluid is measured. Additional methods of determining a concentration of hydrogen sulfide in a fluid within a subterranean formation and related downhole optical sensor assemblies are disclosed.