초록 ▼

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 iso

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. The pumping assembly may be operated to allow selective control of the thermal isolation of the thermal zone; alternatively, the component system may be subject to a controlled temperature by operating the thermal device. A sample mixture passing through the separation column may thereby be exposed to a desired temperature profile according to a selected program so that the sample will separate into its components for subsequent detection by a detector.

대표청구항 ▼

An analytical instrument, comprising: a component system having an active device and a thermal device for altering the temperature of the active device; a thermal isolation system for receiving the component system and providing temperature control of a thermal zone, said active device being located

An analytical instrument, comprising: a component system having an active device and a thermal device for altering the temperature of the active device; a thermal isolation system for receiving the component system and providing temperature control of a thermal zone, said active device being located in the thermal zone, including: a. a housing defining a closed cavity and a cavity volume, said closed cavity being subject to pressurization and thereby having a cavity pressure, said housing including means for locating the component system and the housing in a spaced relationship wherein at least a portion of said component system is enclosed within and detached from said housing, b. a gas supply system responsive to a control signal for providing a first flow of hydrogen gas, c. a pumping assembly having a palladium pumping element located with respect to said closed cavity and operable in response to the provision of first flow for establishing a selectable cavity pressure in the cavity volume and thereby establishing a selected amount of thermal isolation of the thermal zone; and d. a controller operatively connected to the pumping assembly for providing said pressure control signal; wherein said controller includes means for determining a selected cavity pressure and means for providing said pressure control signal in response to said determination so as to control the cavity pressure in the closed cavity, whereby the extent of gas phase heat conduction between said portion of the component system and the housing is selectably controlled.