Abstract: A device for performing sample acquisition and introduction of a selectable quantity of the acquired sample to associated device such as an analytical instrument.

Abstract: An analytical instrument includes a control system, including a computer and a pneumatic controller responsive to the computer, and a planar chromatographic assembly. The planar chromatographic assembly includes a planar pneumatic manifold, a heater/fan assembly for establishing a temperature-controlled zone, an insulating enclosure for confining the temperature-controlled zone to an oven cavity and certain zones of the planar pneumatic manifold, a separation column having inlet and outlet ends attached to couplers at selected internal fluid-bearing conduits in the pneumatic manifold and located closely adjacent the planar manifold and within the temperature-controlled zone, and one or more fluid-handling functional devices attached to the pneumatic manifold for fluid-tight communication with respective internal etched channels provided within in the planar pneumatic manifold.

Abstract: Electron capture detector for use with an effluent stream from a gas chromatograph includes an ionization cell and a sample inlet system connected to the ionization cell for providing an effluent fluid having a sample concentration therein. In the preferred constant-current, variable frequency mode of operation, a cell current is measured and compared to the reference current. The pulse rate is then adjusted to maintain a constant cell current. The pulse rate is converted to a voltage, processed according to a novel linearization formula, and recorded. The ionization cell includes a radioactive ionization source and the ionization cell defines an optimized cell volume in which the electron capture reaction is forced to occur according to a concentration mode of operation. Improved sensitivity in the electron capture detector may be achieved by restricting the effective radioactivity in the ionization cell to be in the range of 0.5 to 3 milliCuries, and preferably in the range of 1 to 2 milliCuries.

Abstract: A planar separation column device for use in gas or liquid phase sample analysis. The planar separation column device includes complementary microstructures formed in a planar foldable substrate. The complementary microstructures may be superimposed in a controlled manner by folding the foldable substrate. The resulting integrated assembly may be bonded and subsequently operated in an associated sample analysis system. The planar separation column device includes etched features useful for integrated sample analysis, such as for integration of analyte inlet, detection, and fluid communication devices.

Abstract: A thermal conductivity detector includes a cavity wall defining a cavity for receiving a quantity of a sample fluid, the cavity wall being subject to a cavity wall temperature that is temporally and spatially variable, and a sensor located in the cavity and connected preferably in a bridge circuit configuration for providing a temperature sense signal. The sensor exhibits a resistance which is dependent on a temperature of the sensor. A first signal providing means includes reference means preferably in the form of first and second reference resistors located within first and second reference resistor cavities. The first and second reference resistors are connected to a reference voltage in a voltage divider network such that a node of the voltage divider network provides a temperature compensation signal that is representative of the average temperature of the cavity wall.

Abstract: A chromatograph includes an injector for receiving a sample and a pressurized carrier fluid flow and in response providing a sample/fluid mixture; a separation column located in a temperature-controlled zone for receiving the sample/fluid mixture and for providing a column effluent stream; a pneumatic detector having an orifice for receiving the effluent stream; means for sensing the volumetric flow rate of the fluid mixture entering the column and for generating a respective flow rate signal; means for sensing the column input pressure and generating a respective input pressure signal; an electronic pneumatic controller including means for receiving the flow rate signal and input pressure signal and for controlling in response the input pressure and the volumetric flow rate of the carrier fluid; and means for detecting a change in the pressure of the effluent stream at the orifice in response to a change in the density of the effluent stream passing through the orifice and for generating a representative out

Abstract: A flow conditioning system includes a flow randomizing section for receiving an input fluid stream and for increasing the uniformity of the streamwise velocity components of the input fluid stream while randomizing the non-streamwise velocity components, so as to provide a randomized fluid stream; a flow expansion section for receiving the randomized fluid stream and damping the non-streamwise velocity components therein, so as to provide a damped fluid stream; and a flow straightening section for receiving the damped fluid stream and for dividing the damped fluid stream into multiple, parallel output substreams so as to provide a laminar flow profile in an output fluid stream.

Abstract: Electron capture detector for use with an effluent stream from a gas chromatograph includes an ionization chamber and a sample inlet system connected to the ionization chamber wherein the sample inlet system effects uniform fluid mixture of the effluent fluid and a make-up gas prior to entry of the fluid mixture into the ionization chamber. A preferred mixing device includes a column liner having a flow acceleration region wherein a localized reduction in the internal diameter of the liner causes momentary turbulence of the fluid mixture.

Abstract: Sample analysis in a portable analytical instrument, preferably in the form of a gas chromatograph, benefits from temperature control of one or more thermal zones in the instrument by way of a thermal isolation system that includes a novel pumping assembly to effect a selective amount of thermal isolation of the thermal zone. The pumping assembly includes a pumping element in the form of a tubular or planar palladium structure. The pumping assembly makes use of the unique properties of palladium to allow selective control of a nominal gas pressure within a vacuum cavity. A component system, which may include a separation column and a thermal device for heating and/or cooling the component system, may be provided within the vacuum cavity. The thermal device and the pumping assembly are individually controlled by a control system.

Abstract: Electron capture detector for use with an effluent stream from a gas chromatograph includes an electron source means and an adjacent ionization chamber in which electron capture takes place. The active region of the ionization chamber is disposed to receive free electrons and a flow of purge gas. The detector has an inlet port for receiving a sample gas as well as an outlet port for exhausting the sample gas and the purge gas. A collector electrode in the detection chamber is biased so as to collect the free electrons in the absence of electrophilic substance. Electrophilic substances in the detector will reduce the flow of electrons to the collector and generate an ionic current. An insulative member in the form of a flow guide may be located at the portion of the anode so as to permit pulsing of free electrons to the anode but substantially block the ionic current, i.e., to discriminate between the free electrons and the ionic current.

Abstract: A planar palladium structure makes use of the unique properties of palladium to provide a hydrogen permeable membrane suitable for use in providing, for example, selective control of a nominal gas pressure within a cavity. The contemplated planar palladium structure includes a planar substrate having upper and lower major surfaces and an array of microfine channels therebetween, wherein the channels allow gaseous communication between the upper and lower major surfaces, and an array of palladium deposits being distributed on the substrate and located with respect to the microfine channels so as to restrict the gaseous communication to diffusion of hydrogen gas.

Abstract: Method and apparatus for the analysis of one or more analytes present in a sample carried in a first fluid. The first fluid is combined with a first detector fluid and a second detector fluid to provide a fluid mixture which flows across the surface of an igniter. The analytes are ionized by means of an ionization process. The ion current is collected and measured at a collector electrode adjacent to the igniter. The flow of at least one of the first detector fluid and second detector fluid is modulated during an ignition sequence according to predetermined criteria so as to facilitate flame ignition.

Abstract: Methods and apparatus for extracting an analyte from a sample using a field-portable extraction instrument. The preferred embodiment of the extraction instrument includes an extraction fluid source, a sample container, a valve element, a nozzle, and a collection trap vessel. The methods of the present invention include the steps of inserting the sample into the sample container, attaching the sample container to the instrument, and providing a quantity of pressurized extraction fluid from the pressurized extraction fluid source into the sample container to initiate the extraction process. Extraction is facilitated by directing the extraction fluid into the sample at a rapid flow rate such that the sample and extraction fluid are vigorously mixed and a sample/solvent mixture is created. The valve element is then operated to isolate the extraction fluid source and to fully close the sample container.

Abstract: A flexible patient monitoring system which interfaces a telemetry subsystem with a network by way of a telemetry transmission receiving system and a network controller. The telemetry subsystem includes one or more monitoring instruments, a multiport transmitter, a telemetry subsystem interface, a backchannel receiver module, and a telemetry docking station.

Abstract: An analytical instrument preferably in the form of a chromatograph includes a computer, a pneumatic controller responsive to the computer, and planar manifold assembly. The planar manifold assembly includes one or more fluid-handling functional devices that may be surface mounted to a planar manifold. The fluid-handling functional device may be constructed as a valve, operable in response to a control signal from pneumatic controller for controlling fluid flow in selected fluid flow paths in the chromatograph, or as a sensor, a fluid regulator, a fluid flow input or output line, or the like.

Abstract: Sample analysis in a portable analytical instrument, preferably in the form of a gas chromatograph, benefits from temperature control of one or more zones in the instrument by way of thermal energy developed from an energy reservoir. In a preferred embodiment, analytical instrument performs chromatographic analysis and the selected zone comprises a temperature-controlled thermal chamber, or oven (124) which includes a heating unit (118), a temperature sensor (128), and a cooling unit (130). A separation column column (118) is positioned within the oven (124). The energy reservoir comprises a first reservoir (125) of heating fluid in the form of a compressed light hydrocarbon, a second reservoir (126) of a compressed inert gas, or a combination thereof. A controlled temperature in the oven (124) resulting from the operation of the heating unit (118) and/or cooling unit (130) may be effected in response to a control signal generated by a computer (122).

Abstract: Sample analysis in a portable analytical instrument, preferably in the form of a gas chromatograph, benefits from temperature control of one or more thermal zones in the instrument by way of a thermal isolation system that includes a novel pumping assembly to effect a selective amount of thermal isolation of the thermal zone. The pumping assembly includes a pumping element in the form of a tubular or planar palladium structure. The pumping assembly makes use of the unique properties of palladium to allow selective control of a nominal gas pressure within a vacuum cavity. A component system, which may include a separation column and a thermal device for heating and/or cooling the component system, may be provided within the vacuum cavity. The thermal device and the pumping assembly are individually controlled by a control system.

Abstract: An oven for a chromatograph is shown in which an oven vent is located with respect to an oven fan assembly and an oven vent assembly. In certain operating conditions, the oven fan assembly and the oven vent assembly are controlled by a computer to cause an exchange of cavity air and ambient air to decrease the level of concentration of combustible gases present in the oven.

Abstract: An electroacoustic transducer having a base formed of a transducer backing material for use in supporting an array of active elements. The backing material is formed as a composite of a preform, preferably selected according to a fiber architecture, and an acoustically-attenuating matrix. Preferred embodiments of the preform include linear, planar, and integrated fiber systems. A particularly preferred embodiment includes a macroporous mesh structure provided in the form of stacked sheets, or an integrated fiber system, having therein fibers arranged in spaced relationship. The fibers define a plurality of openings which in turn provide voids that may be filled by the matrix via techniques such as vacuum-impregnation.

Abstract: An improved pneumatic control system suitable for use in providing servo control of one or more active devices in an analytical instrument includes a series pass element that effects partial regulation of an unregulated voltage to remove any high frequency supply voltage variations (including but not limited to a ripple component), but need not regulate the low frequency voltage variations, the effects of which are compensated by a loop gain compensation scheme operable in a servo control loop. A digital signal processor employed in the servo control loop uses a voltage sense signal representative of the regulated supply line voltage to generate a correcting term for use in a proportional integral derivative (PID) control algorithm operating in control loop firmware. The correcting term causes an inverse proportional change in the control loop gain.