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: 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: The gas detection apparatus comprises a holder for the temporary fixation of an associated package and which contains a contact surface. A hollow needle having a tip serves to penetrate a portion of the package which is freely exposed at the region of the contact surface. This hollow needle comprises at least two channels. An element serves for the essentially gas-tight connection of the hollow needle tip with the contact surface or the part of the package freely exposed therein. A component is connected by a connection line with one channel of the hollow needle. A suitable membrane-enclosed sensor, such as an amperometric sensor defining a sensor surface formed by a semi-permeable membrane, is preferably suspendingly arranged in the compartment. A preferably closable flushing or purging gas line communicates with the connection line and allows flushing the compartment, the connection line and the one channel.