Abstract: The present invention and its claims encompass principles, methods, apparatus, and applications for detection, quantification, and monitoring of responses of gases, vapors, aerosols, and mixtures thereof to initiators of exothermic reactions. While the invention can be utilized for any concentration level, the intended, normal utilization is for gases in which the concentrations of species capable of participating in exothermic chemistry are too low to support self-sustaining exothermic reactions leading to detonations or deflagrations as well as for gases in which other factors prevent the exothermic reaction chemistry from becoming self-sustaining.

Abstract: The invention is a sensing method and an oxygen sensor for detecting a change of oxygen partial pressure in an ambient atmosphere. The sensor includes a sensing material selected from metal or its oxides which, when at an elevated temperature and exposed to a gas containing a changing partial pressures of oxygen, is capable of changing from one metal or metal oxide phase to another such oxide phase and vice versa. Associated with such phase change is a change in a measurable physical property of the material. Heating elements, connectable to a power source, able to maintain a temperature gradient across said sensing material are necessary to maintain the material, during active sensing operation, in at least two of the phases defining a boundary line therebetween which is generally perpendicular to the longitudinal axis of the temperature gradient.

Abstract: A gas detection and measurement system includes a light source, a light sensor, a test cell body having a first fluid port and a second fluid port, and first and second optical paths from the light source to the light sensor through the test cell. The first and second optical paths have different lengths. As fluid flows through the test cell body, light intensity measurements are taken along the first and second optical paths so that the concentration of a target gas within the fluid can be calculated.

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: A photoionization detector for a gaschromatographic apparatus includes an ionization chamber provided with a polarizing electrode and a collector electrode. The electrodes are mounted on and heated by a base portion of the detector. A lamp with a window spaced from the chamber and mounted on the base portion through supporting means having low thermal conductivity is provided. A gas curtain of a gas that is transparent to the said lamp radiation is provided at least between the window and the ionization chamber and comprises a first portion of substantially still gas acting as thermal insulant and a second portion of flowing gas also acting as sweep gas for the lamp window.

Abstract: A gas detector, preferably for carbon monoxide detection, which includes a light detector(5), a light source (1) for providing a light beam which travels along a light path to the detector and detection chemistry (3) disposed in the light path for altering the light beam responsive to the impingement of a predetermined gas thereon. The detection chemistry includes a plurality of spaced apart members, each disposed in the light path. Each member includes a chemistry responsive to the impingement of the predetermined gas thereon for reversibly altering the light transmissive properties of the detection chemistry. The chemistry of any one of the members can differ from the chemistry of one or more of the other members if more than two members are present. The detection chemistry can, in part, act as a filter to light from the light beam. The detection chemistry is disposed in a gas ambient, the gas ambient being disposed between the spaced apart members.

Abstract: A cartridge for collecting a sample of mercury or other substance of interest has a tubular housing and an insert, for example, of gold or another metal. The insert comprises a number of wire meshes sintered together to form a substantially unitary insert having an extended surface area, or otherwise is formed as a solid with a large surface area. The housing is provided with a groove and an internal projection as a mechanical coupling formations, to engage and retain the insert.

Abstract: The present invention provides lyophilized reagent spheres comprising reagents suitable for analysis of biological samples, in particular analysis of blood samples in centrifugal analyzers. Also provided are diluents which are conveniently used in such analyzers.

Abstract: An improved carbon monoxide sensor system has a dual sensor system having two sensors disposed in a series arrangement within a sensor housing. Each sensor is formed from a porous semi-transparent substrate that is impregnated with a different chemical sensor reagent. At lease one sensor substrate surface is treated with a chemical compound before being impregnated to increase average pore size and, thereby, increase the sensitivity of the sensor. One sensor is formed from a chemical sensor reagent designed to perform at a lower to middle humidity and temperature range. The other sensor is formed from a chemical sensor reagent designed to perform at a middle to high humidity and temperature range. The dual sensor system constructed in this manner provides good carbon monoxide sensitivity at temperature and humidity conditions required by the standards of UL-2034.

Abstract: Mercury Detection Method and Apparatus utilizes cartridges including gold for adsorbing mercury as an amalgam. The adsorbed mercury is desorbed by heating and passed through a Cold Vapour Atomic Fluorescence Spectrophotometer. Each cartridge is flushed with an inert gas, so that air and contaminants are never passed directly through the detector, so only inert gas passes through it. To further prevent adsorption of contaminants, the cartridges are maintained at a minimum temperature, above ambient temperature and below 100.degree. C. To enable unattended calibration, a permeation source is provided having a permeation chamber and a valve assembly, including 3 separate valves, to ensure that in an off state mercury vapour cannot leak to the cartridges. To ensure an efficient use of the inert gas, its flow can be adjusted between 3 different levels, for flushing, desorption of mercury, and an idle state to maintain the apparatus purged air.

Abstract: A photoionization detector (PID) and an improved halogen specific detector are disclosed, for direct connection of the PID outlet to the halogen specific detector inlet. The tandem detector is used for detection of volatile organic compounds and the like. A jet assembly and seal between the PID and halogen specific detector provide a leak free and upswept dead volume-free connection between the two detectors.

Abstract: The present invention provides an apparatus and method for enhancing the response of a biometric sensor for sensing toxins by measuring the rate of change of sensor readings. An LED, optically coupled to the sensor and a photodiode, transmits light through the sensor to the photodiode. The photocurrent from the photodiode is converted to a digital sensor reading value proportional to the darkness of the sensor and is loaded into a microprocessor. In the microprocessor, the sensor readings are essentially differentiated to determine the rate of change of the sensor readings. The rate of change information is used to trigger an alarm condition indicative of a predetermined level of sensed toxins.

Abstract: A detection system for detecting the emission (i.e., the fluorescence or phosphorescence) from a contaminant contained in a sample gas. In order to keep the optics of the system clean and maintain a high signal-to-noise ratio in the detected signal, the detection system contains a housing separated into illumination and sample chambers by an aperture-containing partition. A sample inlet port is connected to the sample chamber, and a purge inlet port is connected to the illumination chamber to direct the purge and sample gasses into their respective chambers. A vacuum system is connected to a vacuum port on the sample chamber to simultaneously draw the sample and purge gasses into their chambers through the inlet ports; the purge gas is then drawn through the aperture and into the sample chamber. Finally, both gasses are drawn out of the sample chamber through the vacuum port.

Abstract: The present invention relates to a sensing instrument and method for measuring the concentration of an analyte. The sensing instrument includes: a sensing element including at least a first emissive indicator characterized by a bimolecular quenching rate constant k.sub.q, one or more fluorescence lifetimes .tau..sub.o above a lowest lifetime .tau..sub.oL, and capable of emitting analyte concentration dependent signals when exposed to an excitation signal in the presence of quencher; an excitation system which provides an amplitude modulated excitation signal at one or more radial modulation frequencies .omega.; a detector; and a processor. The processor univariantly processes the detected signals and provides output signals representative of analyte concentration. The sensing element and/or excitation system are configured to enable the instrument to operate sufficiently within the condition [(k.sub.q [Q]).sup.2 +.omega..sup.2 ].tau..sub.o.sup.2 >>1+2k.sub.q .tau..sub.

Abstract: The present invention is an optical detection and identification system and provides an optic sensor, an optic sensing apparatus and methodology for detecting and evaluating one or more analytes or ligands of interest, either alone or in admixture. The optic sensor of the system is comprised of a supporting member and an array formed of heterogeneous, semi-selective thin films which function as sensing receptor units and are able to detect a variety of different analytes and ligands using spectral recognition patterns.

Abstract: Sensing elements, useful in sensing the concentration of a gas, e.g., carbon dioxide, in a medium, e.g. blood, and methods for making such sensing elements are disclosed. In one embodiment, the method comprises continuously placing a sensing composition precursor in contact with a continuous web, forming a continuous sensing composition from the precursor, and applying a continuous opaque film to the sensing composition. A plurality of individual sensing elements are formed from this composite structure. These sensing elements, which each have very similar sensing characteristics, are placed in a sensor fixture for use.

Abstract: Apparatus for chemical detection includes a cap for coupling with a sample vial containing a sample. The sample includes at least one chemical to be detected. The cap includes a reagent vial which contains a liquid reagent. The reagent vial includes a membrane which substantially retains the liquid reagent and which is substantially permeable to the chemical to be detected. The reagent vial can be opened to allow the chemical to permeate and enter the reagent vial and closed to substantially prevent the chemical from permeating the membrane and entering the reagent vial. In some embodiments, the reagent vial is opened and closed by movement of the reagent vial. In some other embodiments, the reagent vial remains stationary while a device moves to open and close the stationary reagent vial.

Abstract: Apparatus employing vapochromic materials in the form of inorganic double complex salts which change color reversibly when exposed to volatile organic compound (VOC) vapors is adapted for VOC vapor detection, VOC aqueous matrix detection, and selective VOC vapor detection. The basic VOC vapochromic sensor is incorporated in various devices such as a ground probe sensor, a wristband sensor, a periodic sampling monitor, a soil/water penetrometer, an evaporative purge sensor, and various vacuum-based sensors which are particularly adapted for reversible/reusable detection, remote detection, continuous monitoring, or rapid screening of environmental remediation and waste management sites. The vapochromic sensor is used in combination with various fiber optic arrangements to provide a calibrated qualitative and/or quantitative indication of the presence of VOCs.

Abstract: This invention provides a means for detecting local atmospheric contaminants from safe distances. The invention means of a detector system comprise a pulsed laser, a sensitive photo-detector, various optical filters, and necessary digital control circuitry. The detector system employs laser technology in combination with a sensitive photo-detector to achieve detection of any hazardous gas elements or other pollutants remotely located from personnel who may subsequently be exposed. In operation, a pulsed laser or a tunable dye laser is employed as an excitation source for the contaminant or pollutant to achieve excitation of the contaminant or pollutant. When the excited molecule of the contaminant or pollutant returns to ground-state it emits a photon at a given (measurable) frequency. A sensitive photo-detector is filtered to permit detection of only the frequency at which a harmful gas (as an example of a contaminant or pollutant) fluoresces.

Abstract: The adsorption of gas on a solid surface can produce considerable variation in the optical properties of the solid surface and eventually lead to the identification of the gas adsorbed. An optical waveguide having at least a portion of its length circumferentially coated with a transparent semiconductor material may function as a gas sensor. The sensor functions by exchanging electrons with a detectable gas brought in proximity with the coating material at reactive sites on the material's surface by the process of adsorption, thereby varying the refractive index of the transparent semiconductor material and altering the ellipticity of a light transmission through the optical waveguide. Substantially monochromatic polarized light is transmitted through the optical waveguide and then quantified by a light detector. A meter or other device connected to the light detector is adjusted to register a variation in the signal received by the light detector, indicating the presence of a detectable gas.

Abstract: A gas detector for simultaneously detecting a kind of gas to be detected and a gas concentration by simultaneously effecting adsorption-measuring type gas detection and optical gas detection. The gas detector comprises a gas detecting element having a gas sensitive thin film disposed on a piezoelectric vibrating element and adapted to generate fluorescence or phosphorescence when irradiated with a light, an oscillating unit for oscillating the piezoelectric vibrating element, a frequency detecting unit for detecting an oscillation frequency of the piezoelectric vibrating element, a light emitting element for irradiating the gas sensitive thin film with light and a light receiving element for receiving the fluorescence or phosphorescence generated from the gas sensitive thin film and adapted to detect the intensity of the fluorescence or phosphorescence. The gas detecting element is disposed in a reaction tank provided with a gas passageway and having a light transmissive window.

Abstract: For quality control of packaged organic substances, preferably packaged foods and drugs, the materials to be examined are brought into contact with a planar optical sensor element which is applied on the inside of the wrapping and responds to a change in the gas composition in the gas space above the sample by a change in color or fluorescence. The change of one of the optical properties of the sensor element is detected visually or opto-electronically.

Abstract: A elecret substrate (10), which is exposed to the environment so as to collect molecular contamination, lies at the bottom of a holder (20). Above the substrate a sensor head (100) is supported. Signals from the sensor head are relayed to an electrostatic voltmeter (130). The voltage reading at electrostatic voltmeter (130) is a function of the amount of polar molecule contamination on substrate (10).

Abstract: An improved sample cell for use in a gas analyzer has a sample body with a measuring optical path extending traverse to the cell body. A sample gas inlet port is positioned at one end of the cell body, and a sample gas outlet port is positioned at the other end of the cell body. Porous plates can extend across the cell body, and appropriately-dimensioned apertures in the porous plates can ensure a consistent flow path of gas across the optical path without any stagnated flow patterns.

Abstract: The present invention describes the process and apparatus for the simultaneous measurement of sulfur-containing compounds and organic compounds with or without sulfur in their structures. A detector cell is described that allows simultaneous measurement of compounds that can be ionized in a flame and thereby cause the electrical conductivity of the flame to increase, and the selective measurement of sulfur-containing compounds which simultaneously form sulfur monoxide. Sulfur monoxide, upon mixing with ozone, emits light from 240 to 450 nm. The intensity of the light can be measured and related to the concentration of sulfur in the sample, while changes in electrical conductivity of the flame measured by imposing a voltage across the cell quantifies the organic compounds irrespective of whether or not they contain sulfur.

Abstract: The present invention relates to a method and an apparatus for measuring trace quantity of oxygen in a gas by reacting yellow phosphorus vapor and oxygen in a sample gas, and measuring the intensity of the light emitted by the reaction. Together with the sample gas, a constant amount of oxygen is continuously supplied to a reaction chamber so as to react with the yellow phosphorus vapor, and the intensity of the light emitted is measured. The oxygen concentration in the sample gas is determined from the difference between the value measured as above and the intensity of the light emitted by the reaction between the yellow phosphorus vapor and the added oxygen, or from the oxygen concentration obtained from the measured value and the concentration of the added oxygen.

Abstract: Method of performing enzyme assays using the technique of surface plasmon resonance spectrometry (SPRS). An SPRS surface carries an immobilized reagent which is capable of being released by an enzyme. A fluid sample containing the enzyme is brought into contact with the solid surface, and release of the reagent monitored by SPRS.

Abstract: A respirator with an eye space (16), through which the air to be inhaled flows, and with an indicator located on a support for indicating the efficiency of the protective device on the respiration connection, which is to retain the pollutant from the environment. The pollutant indication takes place both in the case of leakages at the sealing zones of the mask or the respiration gas-carrying lines (compressed air respirator) and in the case of insufficient filter effect. To achieve this, the support (10) is arranged on an inner half mask (3) of the respirator, and an access surface, which is exposed to the pollutant and contains the indicator (18, 118), is in flow contact with the air being inhaled, which flows through the passage openings (12, 112) between the eye space (16) of the full mask (1) and the inner half mask space (4).

Abstract: An analytic separation arrangement includes a system of tubes including a separation zone, preferably a separation column, which tubes upstream the separation zone are connected with reservoirs for a carrier and a chemical sample to be seperated and analyzed, and downstream the separation zone are connected with a waste container for the carrier containing the sample and also are connected with transporting means for the carrier and the sample. The tube system is associated with an optical detector for monitoring changes in the absorption, in the fluorescence or in the optical activity of the carrier when it is transported through the tube system and past the optical detector, which is arranged in the path of the carrier behind the separation zone but in front of the waste container. Between the separation zone and the optical detector there is arranged in the path of the carrier a refractive index equalizing unit.

Abstract: A method and apparatus for selective, high speed detection of vapors of specific gas-chromatographically-separable compounds. In the disclosed method separate analyses are performed on two portions of a gas sample formed by flash-heating trapped vapors to successively higher temperatures while flowing hydrogen carrier gas over coatings in/on which the vapors are held. Within a total time interval of about twenty seconds 1) two sample portions are formed, 2) each portion is rapidly separated in two series-connected, high speed, temperature-programmed gas chromatographs, and 3) specific compounds are identified by detection of NO gas formed during an oxidative pyrolysis of each separated portion. One application of the described method and apparatus is the rapid, selective, and sensitive detection of nitrogen-containing compounds such as the drugs methamphetamine, cocaine, and heroin.

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: An apparatus for detecting gaseous aldehydes is disclosed which contains a detachable aldehyde capturing system and an aldehyde detection system. The gaseous aldehyde is passed across a semipermeable membrane with a solvent on the other side of this semipermeable membrane to dissolve and absorb the aldehydes from the gas. This system permits the concentration and detection of low concentrations of gaseous aldehyde in the sample for efficient measurement. The aldehyde dehydrogenase to produce NADH in an amount corresponding to the amount of aldehyde in the solvent. The aldehyde detection system measures the amount of NADH produced.

Abstract: An oxygen sensor is provided for determination of the partial pressure of oxygen. In one aspect, the invention consists of oxygen-quenchable luminescent lanthanide complexes for an oxygen sensor. The complexes are oxygen-quenchable even though immobilized in a solid matrix, such as a solid polymeric matrix, and preferably are terbium complexes of Schiff base or .beta.-diketone ligands. Certain preferred processes are described for improving the oxygen sensitivity of the lanthanide complexes. In another aspect, the invention consists of a combination measuring and reference analyte sensor containing both quenchable and nonquenchable luminescent materials. The materials luminesce at different wavelengths and thus may be transmitted together down a single optical fiber and later discriminated by means of filters and separtely detected. In a third aspect, the invention consists of a low-noise phosphorescent analyte sensor employing a gatable detector.

Abstract: In an external lasing dye sensor system, a stream of lasing dye free-flows cross an open area inside a chamber. An air sample comprising chemical vapor contaminants is pumped or drawn into the chamber. A laser beam is introduced into the chamber intersecting the lasing dye. A chemical reaction between the contaminants and the lasing dye result in a change in the emission spectra of the lasing dye. The change in emission spectra is detected and thus provides an improved apparatus for detecting low concentrations of chemical vapors in an air sample.

Abstract: A sensor and a method for using the sensor to determine the concentration or partial pressure of oxygen in a fluid media is provided. The sensor includes a light modifying medium containing a luminescent dye which is accessible to oxygen. The luminescent dye contains a hexanuclear core of molybdenum, tungsten or mixtures thereof having 14 coordination sites, wherein each site is occupied by a ligand. The sensor also includes an apparatus capable of transmitting and collecting light to and from the light modifying medium.

Abstract: In order to obtain a high precision of measurement which is independent of the soot content of the exhaust gas to be tested in a given process, the proposal is put forward that the volume of exhaust gas taken for each loading of the filter be determined by means of a suitable algorithm from the value of filter blackening obtained in a previous test, sampling being continued if the blackening of the filter is outside a specified range.

Abstract: Disclosed are a method and apparatus for high speed, selective detection of vapors of specific compounds, particularly nitrogen-containing compounds, utilizing, a bypass branch and high speed gas chromatography for improved selectively and sensitivity of detection. A system with two gas chromatographs (GC's) alternating in series with two pyrolyzers provides two time intervals of detection in a downstream detector, with the second time interval containing signals delayed and further separated relative to signals from the first time interval. The bypass branch, in diverting a portion of the flow of gas samples from passage through the second gas chromatograph and second pyrolyzer, avoids interferences in the first time interval of detection from non-GC-retained compounds decomposed in the second pyrolyzer. Also disclosed is an arrangement for rapid, precise heating of vapor concentrator tubes in which vapors are rapidly focussed and then injected into a GC, and for rapid, precise heating of the GC's.

Abstract: In a device for analyzing samples for mercury and/or hydride-forming elements by means of atomic absorption spectroscopy, a first arrangement for determining the mercury according to the amalgam method comprising passage throttling means in the form of a washing bottle and a tube connected downstream to a reaction vessel, the other end of which tube is connected to the measuring cell. The tube contains a gold net adapted to be heated and recooled according to the amalgam method. The second arrangement by which hydrides of the sample are directly connected to the measuring cell employs a conduit which leads directly to the measuring cell, bypassing the gold net by branching off from between the reaction vessel and washing bottle. The tube is connectable to a carrier gas source between the washing bottle and position of the gold net in the tube through a first shut-off valve. A second shut-off valve is arranged in the conduit directly leading to the measuring cell.

Abstract: The present invention relates to a biomimetic sensor for detecting the presence of airborne toxins, such as carbon monoxide, mercury, ethylene oxide, volatile organic materials, and hydrogen sulfide. The biomimetic sensor, which has a functional life of at least one year, comprises a porous, semi-transparent substrate into which is impregnated a self-regenerating chemical sensor reagent. The response of the biomimetic sensor mimics the human response to such toxins, with respect to sensitivity and affinity. The extended functional lifetime of the biomimetic sensor and the mimicking of the human response to the toxins are achieved by the use of a molecular encapsulant that encapsulates at least one component of the chemical sensor reagent.

Abstract: An arrangement for optical measuring concentration of substances has a measuring space which is composed of a material selectively permeable for particles to be measured, acting back on the particles and transparent for a measuring radiation, and a measuring space is arranged in working connection with the object to be measured and the measuring radiation passes through the measuring space. The measuring space has a layer that is a water-insoluble solvent or made of poly(ethylene terephthalate) or polytetrafluoroethylene. The layer excludes a reaction from the particles to be measured.

Abstract: A method for determining the presence of an analyte in a fluid is described along with various components of an apparatus specifically designed to carry out the method. The method involves taking a reflectance reading from one surface of an inert porous matrix impregnated with a reagent that will interact with the analyte to produce a light-absorbing reaction product when the fluid being analyzed is applied to another surface and migrates through the matrix to the surface being read. Reflectance measurements are made at two separate wavelengths in order to eliminate interferences, and a timing circuit is triggered by an initial decrease in reflectance by the wetting of the surface whose reflectance is being measured by the fluid which passes through the inert matrix. The method and apparatus are particularly suitable for the measurement of glucose levels in blood without requiring separation of red blood cells from serum or plasma.

Abstract: This invention is a method and apparatus for detecting the presence of gaseous oxygen and measuring the amount present. In the practice of the invention, luminescence from a luminophor compound is quenched by oxygen. The luminiphor is a conjugated aromatic carbonyl. The intensity of the emitted light is related to the concentration of oxygen in the atmosphere surrounding the conjugated aromatic carbonyl compound. The luminophor compound is located on a polar substrate having free hydroxyl groups at its surface and also having at its surface, in locations adjacent to the luminophor compound, a halogenated hydrocarbon compound containing at least one halogen selected from a group consisting of chlorine, bromine, and iodine. In a preferred embodiment, the invention comprises an oxygen sensor utilizing a fiber-optic light guide to conduct excitation light to a substrate comprised of activated silica gel particles having methylene chloride and N-methylacridone co-deposited on them.

Abstract: Due to the size of the devices used for the excitation and measuring of light, conventional sensor elements for optically determining the concentrations of substances contained in gaseous and liquid samples, featuring an indicator layer with one or more indicator substances, are not well suited for use with microanalysis equipment, nor are they easy to mass-produce. These disadvantages are eliminated by using a unitary sensor element having a carrier layer, at least one photosensitive element with electric contact leads in contact with the carrier layer, and an indicator layer containing an indicator substance.

Abstract: Quenching luminescence of the tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) perchorate, immobilized in a silicone rubber by oxygen is shown to be an accurate and precise method for measuring oxygen concentration in solutions and in the gas phase. Quenching can be quantitated by either lifetime or intensity quenching measurements. Strong aqueous acids and bases, complexing agents, oxidants, and reductants do not penetrate the hydrophobic polymer and, therefore, do not affect the response. Gaseous interferents, such as H.sub.2 S, anesthesia gases (e.g. N.sub.2 O, Halothane), and fluorocarbons do not affect the response. Chlorine and especially SO.sub.2 cause strong, but reversible interference presumably because of electron transfer quenching. A system with a response time of less <0.2 s is disclosed, which is adequate for the monitoring of breathing subjects.

Abstract: A method and apparatus for rapid analysis of a sample medium, particularly a flowing sample medium employ light of a defined wavelength which is guided onto a luminescent layer in contact with the sample medium, the luminescent properties of the layer varying in dependence upon characteristics of the sample medium which are to be analyzed. The luminescent light is monitored by detectors, the detector signals being a measure for the characteristic of interest. For undertaking identification of a particular characteristic with very short follow-up time, even in the presence of a number of other characteristics which influence the luminescent properties, the luminescent intensity is identified for a number of different wavelength regions corresponding in number to the number of characteristics, each characteristic differently influencing the luminescent properties in at least one wavelength region.

Abstract: The molecular concentration of a constituent such as oxygen of an anesthetic agent in a gas is measured by contacting the gas with the surface of a solid body, momentarily heating the surface so that the constituent reacts at the surface to alter a property of the surface such as reflectivity, and determining the degree or rate of alteration occasioned by the heating step. The momentary heating operation may be performed by light from a laser focused on to a small localized region. The body surface can include a thin film of a material such as a metal reactive with the gas constituent of interest at elevated temperatures. The preferred methods provide extraordinarily rapid response, and also form a permanent record of each measurement. Where the gas is at substantially constant pressure, the measured molecular concentration can be interpreted as an indication of the proportion of the constituent in the gas.

Abstract: The invention relates to a dosimeter wherein the substances to be detected color a chemical sensor layer. The degree of coloration of the chemical sensor layer is measured by a photometric diffusion-reflectance measuring device. This dosimeter is improved with respect to a measurement occurring during the time that the contaminant substance is effective. The foregoing is accomplished with the dosimeter of the invention in that the dosimeter has a measuring chamber which receives a diffusion element and with a light impermeable wall portion which closes off the diffusion element while at the same time being permeable to the substance to be detected. A light source and a photosensor are arranged in the measuring chamber.

Abstract: A system for detecting analytes in air or aqueous systems includes a permeation absorption preconcentrator sampler for the analytes and analyte detectors. The preconcentrator has an inner fluid-permeable container into which a charge of analyte-sorbing liquid is intermittently injected, and a fluid-impermeable outer container. The sample is passed through the outer container and around the inner container for trapping and preconcentrating the analyte in the sorbing liquid. The analyte can be detected photometrically by injecting with the sorbing material a reagent which reacts with the analyte to produce a characteristic color or fluorescence which is detected by illuminating the contents of the inner container with a light source and measuring the absorbed or emitted light, or by producing a characteristic chemiluminescence which can be detected by a suitable light sensor. The analyte can also be detected amperometrically.

Abstract: According to the invention, cyanide concentrations of approximately 0.001 to 5 mg cyanide/1 are colorimetrically determined in a continuous manner by means of the known cyanidepicric acid color reaction. The solution containing free cyanide and/or cyanide releasable from cyanocomplexes is converted in a system enclosed in a gas-tight manner in the presence of chelate complexing agents, picric acid and alkaline buffer systems in 1-60 minutes at 50.degree.-120.degree. C. to the color complex and the absorbency is measured spectrophotometrically. The method avoids the extraction step which was previously necessary under 0.2 mg CN/1, avoids errors due to HCN gas evolution losses, is easy to manage, not prone to trouble and suitable for the continuous monitoring of waste-water streams or for controlling cyanide detoxification methods.

Abstract: The present invention is directed to a chemically sensitive component including an optical filter that reversibly changes color or transparency in response to a gas or vapor to be determined or detected. The optical filter comprises a mixture of a basic or acid color former or dye of the triphenyl methane system and a complementary acid or basic compound which may be embedded in a matrix and/or applied as a coating to a carrier. The optical filter's change in color or transparency can be measured photoelectronically, e.g., with a luminescent diode as a light source and a photodiode or a phototransistor as a light detector.