Abstract: A method and apparatus for measuring the concentration of at least one gaseous component and/or vaporous component of a gaseous mixture in which a controlled sensor flame is introduced into the gaseous mixture and at least one narrow spectral band in the controlled sensor flame is optically measured. The concentration of the gaseous component using a result obtained from the optical measuring of the at least one narrow spectral band is then calculated. The method of this invention is particularly suitable for substantially real-time control of combustion processes.

Abstract: A gas sensor for use in monitoring gases such as H2S, NO2 or SO2 comprises a film or layer of non-protonated polyaniline as the gas sensing material.

Abstract: A gas sensor for sensing NOx having electrochemical cells wherein dielectric material surrounds electrolytes except where electrodes are attached. Thereby, the exhaust gas is effectively prevented from contacting the electrolytes of the sensor's electrochemical cells. With the use of this technique, signal cross talk is minimized while enhancing NOx sensing sensitivity. Further, the total number electrodes needed are reduced which allows for more complex sensors structures.

Abstract: In this invention, a mixture of a diazotizing reagent which reacts with nitrous ions to produce a diazo compound, a coupling reagent which couples with a diazo compound to produce an azo dye, and an acid is placed in pores of a transparent porous body to prepare a sensor element. Nitrogen dioxide gas is sensed in accordance with a color change before and after the sensor element is exposed to air to be measured for a predetermined time.

Abstract: In accordance with the present invention, there are provided articles for use in non-invasive measurements of nitric oxide levels in a variety of fluid media, e.g., in mammalian body fluids. Articles according to the present invention comprise a nitric oxide trapping agent contained within a vessel, wherein the vessel comprises a semi-permeable membrane. Nitric oxide diffuses through the semi-permeable membrane and is trapped therein for subsequent quantitative analysis. Articles of the present invention are particularly useful in selectively detecting nitric oxide in the presence of other NOx species.

Abstract: This is a method and apparatus for accurately determining a NOx concentration of a measurement gas that contains H2O and/or CO2, without being affected by a dissociation of H2O and/or CO2.

Abstract: A stable sensor designed to detect accurately the total NOx concentration under 100 ppm in terms of the NO gas concentration is made up of a first cell and a second cell with a gas diffusion aperture provided between the two cells. The first cell has a partition wall of a substrate of oxygen ion conductor containing zirconia as the main component and permitting a gas to be detected to enter the zirconia substrate; oxygen pumping electrodes are also formed on the first cell substrate which functions to expel oxygen in an atmosphere of the first cell to the outside and to reduce NO.sub.2 of the NOx gas to be detected to NO gas.

Abstract: A detector for detecting and measuring nitric oxide. Gas-permeable capillary membrane fibers transport a reagent solution through a plenum containing gases to be measured. Nitric oxide molecules penetrate the walls of the fibers and undergo a chemiluminescent reaction within. The fibers and the plenum are translucent, allowing photons emitted by the chemiluminescent reaction to escape and be detected by a photodetector. The reagent is buffered at an alkaline pH and mixed with the enzyme carbonic anhydrase to minimize the measurement errors caused by the presence of carbon dioxide in the gas to be measured.

Abstract: An apparatus for sensing low concentration NOx in the atmosphere is disclosed. The apparatus has sensor elements arranged in a flow path of the atmosphere, the resistance of each of said sensor elements varying in response to changes in NOx concentration of the atmosphere; a catalyst arranged between said sensor elements to maintain partial pressures of NO and NO.sub.2 in the atmosphere at an equilibrium state; and measuring means for receiving signals from said sensor elements, one sensor element being contacted with the atmosphere which is not passed through said catalyst and the other sensor element being contacted with the atmosphere which is passed through said catalyst and for determining the concentrations of NO.sub.2 and NO in the atmosphere on the basis of said signals.

Abstract: A system for measuring the non-methane HC concentration of gas sample, e.g. automotive exhaust gas, comprising first and second catalytic differential calorimetric sensors. The first catalytic differential calorimetric sensor is capable of producing a first output signal representative of the exothermic effect of the oxidation of the predominate oxidizable species (CO+H.sub.2 +non-methane HC combination) in the gas sample. The second catalytic differential calorimetric sensor is capable of producing a second output signal representative of the exothermic effect of the combined oxidation of the CO+H.sub.2 +alkene hydrocarbon species in the gas sample. Lastly, the system includes a means for comparing the first output signal with the second output signal, thereby indicating the total concentration of unburned aromatic and alkane hydrocarbon species in the gas sample which directly correlates to the total non-methane HC concentration.

Abstract: A method for measuring NO.sub.x in biochemical processes which includes a) isolating a liquid sample; b) adjusting the pH or ionic strength of the sample; c) recording mV values present in the sample after predetermined time periods; d) determining NO.sub.x concentrations in the sample at each of the predetermined time periods from the mV values; e) determining the difference in NO.sub.x in the sample from the NO.sub.x concentrations at each of the predetermined time periods; and f) determining the NO.sub.x concentration of the liquid sample from the difference in NO.sub.x and the predetermined time periods.

Abstract: A method and apparatus for detecting NO.sub.x by chemiluminescence. The apparatus includes a sample gas line having an inlet port for receiving a sample gas, a NO.sub.x converter connected to the sample gas line, a N.sub.2 diluting gas line connected to the sample gas line upstream from the NO.sub.x converter, a bypass exhaust lie connected to the sample gas line, and a chemiluminescence analyzer connected to the NO.sub.x converter. The sample gas, which contains a NO.sub.x component, is introduced to the sample gas line through an inlet portion. The sample gas is diluted with nitrogen gas from the nitrogen diluting gas line, and the NO.sub.x component in the sample gas is converted to NO by the NO.sub.x converter. The chemiluminescence analyzer detects the NO.sub.x component.

Abstract: Disclosed is an oxide sensor in which a measuring electrode is arranged at a distance d to satisfy -3t.ltoreq.d.ltoreq.3t for a downstream end of an inner pumping electrode for a first chamber, i.e., the end located on a side of a second diffusion rate-determining section, provided that d represents a distance between the measuring electrode and the downstream end in a positive direction directed from the first chamber to a second chamber, and t represents a height of the first chamber. A partial pressure of oxygen in the first chamber is measured by using the measuring electrode. A main pumping cell is subjected to feedback control on the basis of a measured value so that the partial pressure of oxygen in the first chamber is controlled. After that, a measurement gas is introduced into the second chamber. Oxides contained in the measurement gas are decomposed by the aid of a detecting electrode or a catalyst.

Abstract: The excitation of the target nitrocompound with ultraviolet radiation ress in photodissociation yielding vibrationally excited NO with significant population of the v"=1 and v"=2 levels of the ground electronic state. As the population distribution of ambient NO favors the v"=0 level, discrimination between vibrationally excited NO and ambient NO is possible by probing the NO A-X (0,0),(1,1), and (2,2) bands near 226, 224, and 222 nm, respectively, employing (1+1) resonance-enhanced multiphoton ionization (REMPI). Many complex nitrocompounds cannot be photolyzed near 452 nm since their absorption cross sections are relatively small. Thus, the visible laser radiation is used to facilitate the detection of ambient NO and NO from NO.sub.2 by (2+2) REMPI and to discriminate these species from more complex nitrocompound analytes. The analytical utility of the present invention has been demonstrated at several photolysis/ionization wavelengths for NO/CH.sub.3 NO.sub.2 and NO.sub.2 /CH.sub.3 NO.sub.2 mixtures.

Abstract: Nitrosyl (FeII) hemoglobin can be detected in biological samples, using a method which involves injections of samples into a photolysis cell, prior to detection of chemiluminescence generated by the reaction between nitric oxide and ozone. This method is useful for monitoring the levels of nitric oxide bioactivity in both normal physiological states, and disease states, such as septic shock, atherosclerosis, thrombosis, hyperhomocysteinemia, pulmonary hypertension, malignancy, infections and central nervous system disorders.

Abstract: Non-invasive methods have been developed for the measurement of NO levels in a variety of fluid media, e.g., body fluids. The present invention embraces the use of a semi-permeable vessel wherein said vessel contains an NO reacting substance to trap NO diffusing thereinto, and a simple physical or chemical detection method to measure the levels of the end products. Since NO is a neutral gas molecule, it is capable of diffusing freely across a wide range of biocompatible polymer membranes which exhibit a high permeability to NO and other neutral gas molecules, such as O.sub.2 and CO.sub.2, but which are not permeable to charged molecules, such as NO.sub.3.sup.- or NO.sub.2.sup.-. The latter two compounds are ubiquitously present in body fluids and often interfere with the measurement of NO levels. The permeability of selected membranes to NO, but not to NO.sub.3.sup.- or NO.sub.2.sup.

Abstract: A device for sensing ammonia (NH.sub.3) and nitrogen oxide (NO.sub.x) gases comprising: a sensor for detecting said ammonia and said nitrogen oxide gases, said sensor including a substrate and a layer consisting of cuprate material for detection of said ammonia and said nitrogen oxide gases, wherein said layer of cuprate material is selected from the group consisting of Y:Ba:Cu:O (YBCO) and Bi:Sr:Ca:Cu:O (BSCCO); a sensor holder for supporting said sensor; a perforated cap positioned over said sensor, said perforated cap having openings for passage of said ammonia and said nitrogen oxide gases to said sensor; a detection circuit communicating with said sensor for measuring output from said sensor; and a display or recording device connected to said detection circuit for displaying or recording a concentration of said ammonia and said nitrogen oxide gases based on the output from said sensor.

Abstract: A nitrogen oxide detecting sensor, according to the present invention, incorporates a gas detecting portion including, as a main component thereof, an oxide compound having electric conductivity or semiconductivity, the oxide compound having a crystal structure of 2212 phase and expressed generally as: Bi.sub.2 Sr.sub.2 (Ca.sub.1-x Y.sub.x)Cu.sub.2 O.sub.8.+-..delta. where 0.6.ltoreq.x<1; 0.ltoreq..delta..ltoreq.1. Electrodes are electrically connected to the gas detecting portion. When the gas detecting portion is analyzed by X-ray diffraction using cuK.alpha. rays to obtain diffraction peak values thereof in the range of a diffraction angle between 5.degree. and 65.degree., the diffraction peak values having a sum .SIGMA. I?2212! expressed by one of the following:(a) .SIGMA. I?2212!/.SIGMA. I?T!>88.1%(b) {.SIGMA. I?2212!+.SIGMA. I?2201!}/.SIGMA. I?T!>94.8%(c) {.SIGMA. I?2212!+.SIGMA. I?Y.sub.2 O.sub.3 !} .SIGMA. I?T!>88.1%(d) {.SIGMA. I?2212!+.SIGMA. I?(Bi, Ca) O!}/.SIGMA. I?T! >88.8%where .

Abstract: A nitrogen oxide sensor and a method of manufacturing the sensor are disclosed. The sensor has a gas detecting portion including sensitive material having electric property thereof subject to change in association with presence of nitrogen oxide in gas and a pair of electrodes electrically connected with the gas detecting portion. The gas detecting portion includes, as a main component thereof, metal oxide compound represented by a general formula:Bi.sub.2 Sr.sub.2 (Ca.sub.1-x Y.sub.x)Cu.sub.2 O.sub.8+y(0.8.ltoreq.x.ltoreq.1; 0.ltoreq.y.ltoreq.1)and having the 2212 phase crystal structure and crystalline size greater than 100 .ANG..

Abstract: A subsurface soil contaminant identification system employs a cone penetrometer unit for continuously measuring the concentration of energetic materials in potentially contaminated soils. The sensor is rugged, reliable, and has a fast response time. The invention utilizes two pulsed, time-delayed miniature lasers. An infrared laser is used for decomposing the energetic material into NO and other products, while a visible laser operating near 452 nm is used for NO detection by (2+2) resonance-enhanced multiphoton ionization (REMPI). The system employs a fiber optic to transmit the output radiation at distances of approximately 30-50 meters, a lens assembly to focus one or both laser beams, a pair of miniature electrodes to collect the ions, a penetrometer, and data acquisition/processing equipment. A REMPI spectrum of 0.1% NO at atmospheric pressure reveals that the spectral resolution is sufficient such that characteristic spectral features of NO can be identified unequivocally.

Abstract: A gas analyzer system for providing a spectroscopic analysis of the sample gas. This analysis is accomplished by first introducing the sample gas into the inlet of the system and transporting it to a spectral analyzer. The sample gas is then spectrally analyzed and the analyzer outputs a signal indicative of a radiation intensity spectrum associated with the analyzed sample gas. A processing unit uses the analyzer signal to detect the presence of one or more prescribed gases and to determine the concentration of each of the prescribed gases in the sample gas. Next, the reacting agent is supplied to the sample gas to convert one or more gases whose presence in the sample gas cannot be detected via spectral analysis due to the masking effects other gases present in the sample gas. The masked gases are converted to secondary gases at least one of which is readily detectable via spectral analysis.

Abstract: An NOx sensor has the sensor element made of an oxide, the resistance of which is varied in response to an NOx component in a gas to be measured, and a measuring portion for measuring a resistance variation of the sensor element and for detecting an NOx concentration in the gas to be measured. A catalyst is arranged at an upstream side of a flow of the gas to be measured with respect reach to the sensor element, which makes a partial pressure ratio of NO/NO.sub.2 reach to an equilibrium state and removes a CO component from the gas to be measured. A heater for adjusting a temperature is arranged at a position close to the sensor element, which maintains temperatures of the sensor element and the catalyst constant. An O.sub.2 sensor is arranged at a position close to the sensor element so that the measuring portion can detect accurately the concentration of Nox in the measurement gas by reference to the resistance of the sensor element.

Abstract: A method of monitoring compliance of a patient that has been placed on a medication maintenance program with a prescribed medication dosage by determining a normalized urine medication concentration. An unadulterated urine sample is obtained from the patient. The urine medication concentration and urine specific gravity are measured. The normalized urine medication concentration is calculated as a function of the measured medication concentration in the urine and the urine specific gravity. The calculated normalized urine medication concentration is compared with an expected medication concentration value for the patient for the maintenance program prescribed to determine any significant differences therebetween as an indication of noncompliance. Alternatively, a urinary-parameter normalized urine medication concentration is calculated as a function of the measured medication concentration in the urine, the urine specific gravity and at least one selected pharmacokinetic parameter of the medication.

Abstract: A method and apparatus for the chemiluminescent determination of NO/NO.sub.x in a sample gas is disclosed in which the NO.sub.x portion of the gas stream is catalytically converted in a preconditioned vitreous carbon bed at a relatively low temperature effective to catalytically convert NO.sub.x to NO and below 200.degree. C. The vitreous carbon is preconditioned by heating at a temperature of between 300.degree. C. and about 500.degree. C. for a sufficient period of time, on the order of two to five hours. The apparatus consists of a converter containing the preconditioned vitreous carbon in communication with a reaction cell consisting of a hollow cylindrical housing having an open end closed by an optical filter. A suitable photodetecter is disposed to detect light emitted through the optical filter. A chemiluminescent reaction between ozone and NO in the sample stream occurs in a reaction chamber defined by the interior of the housing. A reflector element may be disposed in the reaction chamber.

Abstract: A gas sensor for use in monitoring gases such as H.sub.2 S, NO.sub.2 or SO.sub.2 comprises a film or layer of non-protonated polyaniline as the gas sensing material.

Abstract: Apparatus for preconcentrating trace amounts of organic vapors in a sample of air for subsequent detection, comprising a metallic substrate; a thin film of fullerenes deposited on the metallic substrate for adsorbing the organic vapors on the thin film of fullerenes, thereby preconcentrating the organic vapors; and apparatus for heating the metallic substrate to a predetermined optimum temperature for desorbing the vapors from the thin film of fullerenes to form desorbed organic vapors for subsequent detection.

Abstract: An NO.sub.x analyzer capable of reducing maintenance operations for removing solid substances from the analyzer, and for obtaining an analytical value of improved reliability for sample gases flowed through the analyzer is provided. A sample gas supply passage on the downstream side of an NO.sub.x convertor is provided with a first capillary therein; a sample gas supply passage between the first capillary and the NO.sub.x convertor is provided with an overflow passage having a second capillary branch connected therewith; a sample gas supply passage on a downstream side of the first capillary is provided with a diluent air supply passage having a third capillary therein and also branch connected with the sample gas supply passage. At least the confluence of the first capillary, the second capillary, and the diluent supply passage with the sample gas supply passage is arranged within a heating zone of the NO.sub.x analyzer.

Abstract: A method of detecting nitric oxide in an aqueous body fluid of a mammal comprises introducing into the body fluid the agents required to form a water-soluble, stable, paramagnetic complex with nitric oxide and then subjecting the body fluid to magnetic resonance methods which can detect the complex to determine if any nitric oxide was present. A paramagnetic complex containing nitric oxide also is described, as well as, a method of diagnosing septic shock in a mammal by stabilizing and detecting the presence of nitric oxide in a body fluid of the mammal.

Abstract: This invention is a process for detecting low levels of nitrogen oxides (NO.sub.x) in a flowing gas stream (typically an exhaust gas stream) and a catalytic NO.sub.x sensor which may be used in that process.

Abstract: A highly selective, sensitive, fast detection system and method are disclosed for detecting vapors of specific compounds in air. Vapors emanating from compounds such as explosives, or stripped from surfaces using heat and suction from a hand-held sample gun, are collected on surfaces coated with gas chromatograph (GC) material which trap explosives vapors but repel nitric oxide, then are desorbed and concentrated in one or more cold spot concentrators. A high speed gas chromatograph (GC) separates the vapors, after which specific vapors are decomposed in two pyrolyzers arranged in parallel and the resulting nitric oxide is detected. A low temperature pyrolyzer with silver produces NO from nitramines or nitrite esters; a high temperature pyrolyzer decomposes all explosives vapors to permit detection of the remaining explosives. Also disclosed is a series arrangement of pyrolyzers and gas chromatographs and an NO detector to time-shift detection of certain vapors and facilitate very fast GC analyses.

Abstract: A method for analyzing total bound nitrogen in a sample and providing an output data of total bound nitrogen and constituent compounds (nitrate and nitrite) is disclosed. The total nitrogen bound method provides a discrete sample through a furnace in the presence of continuous flow of water as carrier as well as oxygen carrier gas, resulting in the oxidation of the nitrogen compounds to nitric oxide. The nitrate method involves a discrete sample with water as a carrier provided to a sparge tank. The nitrite is catalytically reduced to nitric oxide in the presence of tartaric acid and ascorbic acid. The nitrate method involves a first conversion to change the nitrate to a nitrite. The first conversion occurs in the presence of a copper-cadmium catalyst causing the formation of the NO.sub.2. The nitrile is subsequently converted into NO. The nitric oxide produced in each of the three methods is measured in a chemiluminescent nitrogen detector.

Abstract: NO.sub.2 and other electron acceptor gases can be detected at 5 volume parts per million by tetrathiafulvalene TTF. The TTF may be incorporated in a polystyrene film, which changes its infra-red spectrum and conductivity upon exposure to such gases.

Abstract: The interference of ozone in the determination of nitrogen dioxide determinations by luminol chemiluminescence is eliminated by first passing the gas sample into contact with a selective reducing agent for ozone, particularly antimony trioxide.

Abstract: A structure and method for sensing oxides of nitrogen in a gas. The gas is first passed through an oxidation catalyst and any reducing species in the gas are oxidized. The output gas from the oxidation catalyst is received by a sensor which generates an output responsive to oxides of nitrogen because the sensor has been isolated from any reducing species in the gas.

Abstract: Chemiluminescence is detected in a luminol solution free of metal ions flowing through a porous material to indicate the presence of certain nitrogen-containing gases. Continuous monitoring of atmosphoric gases is possible through use of the described methods and related apparatus.

Abstract: In a redox reaction process, the oxidized state of organic compounds is increased through the steps of directing oxides of nitrogen together with a reducing agent selected from oxygenated compounds and aromatic compounds through a catalyst bed in the form of supported gold heated to a temperature sufficient to reduce the oxides of nitrogen present to nitric oxide, after which the higher oxidized forms of organic compounds are recovered. The organic compounds to be oxidized can be separated by chromatography before introduction with one of the oxides of nitrogen into the catalyst bed, and detection of the reducing agent by chemiluminescent measurement of NO.sub.2.sup.* enables determination of the higher oxidized species produced.

Abstract: A steam and gas turbine combined cycle plant STAG* employs a catalyst in a heat recovery steam generator to react injected ammonia with NO.sub.x from the combustor of the gas turbine to reduce atmospheric emission of NO.sub.x from the system. Rapid control of ammonia injection is achieved using a prediction of the NO.sub.x being generated in dependence upon the operating conditions of the combustor. A trimming signal from a measurement of NO.sub.x being emitted from the heat recovery steam generator downstream of the catalyst is employed to complete the NO.sub.x control loop. Compensation is provided to relate the measured NO.sub.x downstream of the catalyst with the NO.sub.x in the output of the gas turbine taking into account the catalyst efficiency.

Abstract: A steam and gas turbine (STAG) plant employs a catalyst in a heat recovery steam generator to react injected ammonia with NO.sub.x from the combustor of the gas turbine to reduce atmospheric emission of NO.sub.x from the system. Rapid control of ammonia injection is achieved using a prediction of the NO.sub.x being generated in dependence upon the operating conditions of the combustor. A trimming signal from a measurement of NO.sub.x being emitted from the heat recovery steam generator downstream of the catalyst is employed to complete the NO.sub.x control loop.