Abstract: A photoacoustic device for analysis of fluids. The device is made up of (A) a source of a pulsating beam of light, preferably of the chopper type, and (B) an enclosure, preferably an elongated structure having a generally cylindrical, e.g. essentially tubular shape; and containing and holding--in sonic insulation--at least one reference chamber and at least one measuring chamber in an essentially linear or serial arrangement in a common cell within the enclosure, preferably in an essentially coaxial arrangement; the enclosure and the common cell provide a path P for the pulsating beam of light through the reference chamber and through the measuring chamber. For most purposes, it is preferred that the light beam pass first through the reference chamber and subsequently into the measuring chamber. Optionally, a second reference chamber is arranged at the end of the measuring chamber and a second measuring chamber may follow.

Abstract: A membrane-enclosed sensor (1) of the type having a membrane (11) for exposure to a fluid external phase of analytical interest at an interface between the fluid external phase or sample, and said membrane; the sensor comprises a coiled, e.g. spiraloid, channel (15) at the interface; the channel has an inlet end (16) as well as an outlet end (18) for passing the external phase in contact with the membrane along said coiled channel which, preferably has a length which is at least about 5 times greater than the largest cross dimension of the membrane.

Abstract: An analytic device (1) for reflective luminoscopy comprises within an enclosure (11): a light source (12); a pair of spaced light detectors (141, 142); and a refractor body (16); the refractor body comprises a planar base (161), an entry plane (163) near the light source for light emanating therefrom, and an exit plane (165) near the spaced detectors for light that is being sensed by at least one of the detectors; the entry plane and the exit plane enclose an angle of less then 180.degree. and not less than 90.degree.

Abstract: A probe for measuring the concentration of an alcohol, such as ethanol, in a liquid, such as water. The probe according to the invention has a membrane that is permeable for vapors of the alcohol but substantially impermeable for the liquid; a measuring chamber having an open end closed against the liquid by the membrane is provided and has an inlet and an outlet; a pump or other pressure means serves to feed a purge gas, such as air, via the inlet into and out of the measuring chamber; a valve is provided near the inlet for controlled passage of the purge gas through the chamber; a suitably dimensioned detector including a pellistor or a gas-sensitive resistor is arranged in the measuring chamber for quantitative detection of the alcohol and for generating an electrical signal in proportion with the detection.

Abstract: A method of determining a specific thermal conductivity parameter of a target gas having a known general thermal conductivity and being contained at a concentration of interest in a fluid medium (F) and comprising: contacting said fluid medium with an organic polymer membrane (11) provided at an interface between said fluid medium (F) and a sensing volume (12) containing a thermal conductivity sensor (13); the membrane (11) is substantially impermeable for any liquid components of the fluid medium (F) but has a known permeability for the target gas; the sensing volume (12) is periodically purged or flushed with a gas having a general thermal conductivity that differs from the thermal conductivity of the target gas; permeation of the target gas through the membrane (11) into the sensing volume (12) is permitted intermittently; at least one time-dependent parameter of the known general thermal conductivity of the target gas that has permeated into the sensing volume (12) is measured; and a parameter of analytic

Abstract: The concentration of a gas, such as carbon dioxide, in a fluid medium, such as an aqueous beverage, is monitored by pulsatingly measuring a specific parameter of diffusion of the gas through a membrane that is in contact with the fluid medium and is permeable for the gas but impermeable for the fluid; the gas is allowed to diffuse during a period of time into a receiving space of known volume; the amount of gas that diffuses into the receiving space is determined e.g. by measuring IR-absorption, heat conductivity, volume, pressure or the like physical parameters that depend upon the amount of gas in the volume; this yields a specific diffusion parameter or flux. The gas concentration of interest is then calculated from the specific parameter and a previously determined general parameter of diffusion of the gas through the membrane. Pulsating operation, i.e.

Abstract: Quantitative determination of ozone contained in a fluid by an amperometric method comprises the steps of:(A) providing an amperometric cell having a sensing electrode, a counter electrode, an aqueous electrolyte in contact with the sensing electrode and the counter electrode, and a membrane that is substantially impermeable to the electrolyte but permeable to gaseous media including ozone and oxygen for containing the electrolyte within the cell and for separating it from the fluid maintained external to the cell;(B) providing in the aqueous electrolyte a redox catalyst for chemically transforming the ozone upon its permeation through the membrane into an intermediary electroactive species capable of generating upon reaction with the sensing electrode an indicative electric signal in proportion with a concentration of the ozone in the fluid;(C) applying a predetermined potential across the sensing electrode and the counter electrode;(D) measuring a cell current generated by reaction of the intermediary elect

Abstract: A membrane-enclosed amperometric cell (MEAC) for use in determining the concentration of an electroactive species of interest (EASI) in an ambient medium comprises: a working electrode defined by a periphery; a liquid electrolyte covering the sensing area in a film of uniform thickness and being in electrolytic contact with a counter eletrode; a flexible polymer membrane of generally uniform thickness that is substantially impermeable to the electrolyte but permeable to the EASI; the membrane extends in a substantially conforming manner over the sensing area and the electrolyte film thereon; the cell of the invention has a physical permeation barrier that (1) consists of a layer of a substantially inert solid material which is substantially impermeable to the electrolyte and to the EASI; (2) extends between the ambient medium and the sensing area; (3) is disposed in a parallel configuration and in physical contact with the membrane; (4) has at least one opening permitting access of the EASI through the membra

Abstract: A method for determination of a first electroactive and normally gaseous species (EAGS) and a second EAGS in a fluid medium containing both EAGS; the medium is contacted with a first working electrode that is sensitive but to the first EAGS and generates a first amperometric signal that is indicative of the first EAGS concentration; the medium is also contacted with a second working electrode that is sensitive to both EAGS and produces a second amperometric signal that is indicative of the sum of both EAGS concentrations; the second EAGS concentration is calculated from the difference between the first and the second signal. For example, hydrogen can be measured in the presence of oxygen and this can be applied to monitor a fluid ambient or stream to prevent formation of explosive mixtures or corrosive conditions.

Abstract: Quantitative determination of ozone contained in a fluid by an amperometric method comprises the steps of:(A) providing an amperometric cell having a sensing electrode, a counter electrode, an aqueous electrolyte in contact with the sensing electrode and the counter electrode, and a membrane that is substantially impermeable to the electrolyte but permeable to gaseous media including ozone and oxygen for containing the electrolyte within the cell and for separating it from the fluid maintained external to the cell;(B) providing in the aqueous electrolyte a redox catalyst for chemically transforming the ozone upon its permeation through the membrane into an intermediary electroactive species capable of generating upon reaction with the sensing electrode an indicative electrical signal in proportion with a concentration of the ozone in the fluid;(C) applying a predetermined potential across the sensing electropde and the counter electrode;(D) measuring a cell current generated by reaction of the intermediary el

Abstract: A method for determination of a first electroactive and normally gaseous species (EAGS) and a second EAGS in a fluid medium containing both EAGS; the medium is contacted with a first working electrode that is sensitive but to the first EAGS and generates a first amperometric signal that is indicative of the first EAGS concentration; the medium is also contacted with a second working electrode that is sensitive to both EAGS and produces a second amperometric signal that is indicative of the sum of both EAGS concentrations; the second EAGS concentration is calculated from the difference between the first and the second signal. For example, hydrogen can be measured in the presence of oxygen and this can be applied to monitor a fluid ambient or stream to prevent formation of explosive mixtures or corrosive conditions.

Abstract: A method of thermal protection of a membrane-enclosed amperometric cell of the type comprising an electrolyte within an electrolyte space containing electrodes and enclosed by a semi-permeable membrane which defines a sensor face; heat exchange within said cell is effected for controlled heat compensation of the electrolyte when the sensor face is exposed to temperatures outside of the operative temperature range of the cell.

Abstract: A method of thermal protection of a membrane-enclosed amperometric cell of the type comprising an electrolyte within an electrolyte space containing electrodes and enclosed by a semi-permeable membrane which defines a sensor face; heat exchange within said cell is effected for controlled heat compensation of the electrolyte when the sensor face is exposed to temperatures outside of the operative temperature range of the cell.

Abstract: A method of and a sensor for quantitative electroanalytical determination of elemental hydrogen in a fluid medium are disclosed. A membrane enclosed amperometric cell is used that has at least two electrodes in contact with an aqueous electrolyte to provide a reaction impedance of the cell; the electrolyte is separated from the fluid medium by a membrane that is permeable to elemental hydrogen but substantially impermeable to the electrolyte and provides a membrane impedance of the cell; the electrodes include an anodic hydrogen sensing electrode and a cathodic counter electrode; the sensing electrode has a polished surface consisting of a platinum metal; further, the membrane is selected such that the membrane impedance exceeds the reaction impedance sufficiently to provide for membrane-controlled operation of the cell.

Abstract: A method of thermal protection of a membrane-enclosed amperometric cell of the type comprising an electrolyte within an electrolyte space containing electrodes and enclosed by a semipermeable membrane which defines a sensor face; heat exchange within said cell is effected for controlled heat compensation of the electrolyte when the sensor face is exposed to temperatures outside of the operative temperature range of the cell.

Abstract: When frequency division is used as part of the clock signal regeneration process from a received data signal, a phase ambiguity may occur. A data signal receiver for a bi-phase modulated signal comprises a filter 1 feeding a sampling switch 2 which feeds a polarity detector 3 from which the decoded data is reproduced. The phase of the sampling switch 2 is controlled by the output 6-Q of a .div.2 frequency divider 6 which is driven by a phase-locked loop 5 which in turn is driven by a zero-crossing detector 4 at twice the bit frequency. A monitoring arrangement 8 has sampling switches 10 and 11 driven by outputs 6Q and 6-Q of the frequency divider 6. The data signal applied through a full-wave rectifier 9, is sampled at instants t.sub.o and t.sub.1, at twice the bit frequency.

Abstract: A device for mounting and securing a membrane made of a substantially flat piece of flexible polymer film on an amperometric cell that has a substantially cylindrical cell end frontally provided with an electrolyte-bearing sensor face by means of a removable annular holding member; according to the invention the holding member is a substantially non-resilient and creep-resistant die ring, preferably made of stainless steel, having a cylindrical inner surface that fits slidingly onto the cylindrical cell end and at least one tapered inner surface portion that extends outwardly from the cylindrical inner surface toward a leading end of the die ring; the leading end of the die ring is moved over the cylindrical cell end whereby the polymer film is deep-drawn between the die ring and the cylindrical cell end and is permanently shaped to form a cup-shaped membrane portion extending over the electrolyte-bearing sensor face and the adjacent portion of the cylindrical cell end; the resulting cup-shaped membrane porti

Abstract: A method of mounting and securing a membrane of polymer film on an amperometric cell that has a cylindrical cell end provided with an electrolyte-bearing sensor face; the holding member is a substantially non-resilient and creep-resistant die ring, having a cylindrical inner surface that fits onto the cylindrical cell end; at least one tapered inner surface portion extends outwardly toward a leading end of the die ring; the leading end is moved over the cell end whereby the polymer film is deep-drawn between the die ring and the cylindrical cell end and is permanently shaped to form a cup-shaped membrane portion sealingly held by the die ring on the cylindrical cell end during operation of the amperometric cell.