Abstract: Methods and system for sub-ambient pressure control for column head pressure in gas chromatography (GC) systems. The GC system includes an inlet and a capillary column connected to the inlet. The inlet includes a valve that regulates an inlet pressure and pressure sensor that measures the inlet pressure and outputs a signal that indicates a measured inlet pressure. The GC system also includes an inlet-pressure set-point that can be set to a negative pressure set-point representing a pressure below ambient pressure, the negative pressure set-point driving the valve to change the inlet pressure until the measured inlet pressure equals the negative pressure set-point.

Abstract: High throughput analytical systems and methods employing multiple liquid phase separation process regions coupled to a common mass spectrometer are provided. Disclosed systems and methods permits parallel separation and parallel storage of discrete eluate fractions, followed by sequential discharge and ionization of previously stored eluate portions to yield a composite ion stream containing the sequential series of eluate portions, followed by mass analysis of the ion stream. A common manifold may receive ions and utilize pressurized gas or ion gating to direct ions within the manifold toward the mass spectrometer inlet.

Abstract: A pressure reduction apparatus is disclosed. Air at high pressure and temperature may be drawn from a source such as a bleed valve of a gas turbine engine that supplies the air to an airplane interior. The air is passed to a pressure reduction vessel. The vessel has sufficient volume such that the high pressure air, upon entering the vessel, will reduce in temperature and pressure. The pressure reduction apparatus allows the air to depressurize and drop in temperature to near ambient conditions. Upon exiting the pressure reduction apparatus, the air is at a temperature and pressure sufficient to allow the air to be sampled and analyzed by conventional equipment used for testing for airborne impurities such as semivolatile compounds ad particulates.

Abstract: This invention is a method and device for use with multi-dimensional chromatography that utilizes partial modulation. An analyte-bearing sample is subjected to a first dimension of chromatography. Thereafter the separated analyte-bearing sample is diluted with a modulated second carrier such at the analyte-bearing sample is not stopped or its temperature altered. The partially modulated analyte-bearing sample then feeds into a secondary column where the analyte-bearing sample is further separated.

Abstract: The invention is a device and method in a high-pressure chromatography system, such as a supercritical fluid chromatography (SFC) system, that uses a pump as a pressure source for precision pumping of a compressible fluid. The preferred exemplary embodiment comprises a pressure regulation assembly installed downstream from a compressible fluid pump but prior to combining the compressible flow with a relatively incompressible modifier flow stream. The present invention allows the replacement of an high-grade SFC pump in the compressible fluid flow stream with an inexpensive and imprecise pump. The imprecise pump becomes capable of moving the compressible fluid flow stream in a precise flow rate and pattern. The assembly dampens the damaging effects of an imprecise pump, such as large pressure oscillations caused by flow ripples and noisy pressure signals that do not meet precise SFC pumping requirements.

Abstract: The present invention comprises a method for expediting the analysis of a plurality of samples, preferably using gas chromatography. A specific embodiment comprises a dual isothermal heated zone configuration for use in combinatorial chemistry. This involves partitioning the samples into two isothermal zones, allowing detailed analysis of light components in a lower-temperature zone while heavy components are handled in a higher-temperature zone.

Abstract: A coupling device connecting the output of a microchromatograph (?CG) to the input of a mass spectrometer (MS), said coupling device comprising a capillary tube with one end connected in sealed fashion to the source under vacuum of the mass spectrometer through the intermediary of an interface device, and with the other end connected to the output of the microchromatograph, in slack fashion, open to the atmosphere; the length and the diameter of the capillary tube being chosen such that the flow rate inside the capillary tube is very close to the flow rate at the output from the microchromatograph; the interface device being, furthermore, provided with heating means for very precise adjustment of the flow rate registered by the capillary.

Abstract: Methods and systems for analyzing samples, such as gas samples, are described. One method comprises providing a gas sample, increasing pressure applied to the gas sample to compress the sample to a smaller volume and provide a pneumatically focused gas sample, and analyzing the pneumatically focused gas sample using any of a variety of analytical techniques. Also disclosed are systems for gas analysis, including systems for analysis of pneumatically focused, and thereby concentrated, gas samples and for analysis of particulate matter in gas samples. Analytical systems constructed within personal computer cases also are disclosed.

Abstract: The present invention is a sample valve for use in conjunction with a gas chromatograph. The sample valve design provides for both the inertness and low permeability performance of a diaphragm, and an elastomeric material to apply adequate sealing pressure to the diaphragm to seal with the mating surface of a center plate of the sample valve. This valve design allows the active sealing surface to be well polished without the previous concern for maintaining critical flatness of the mating surfaces of the machined parts.

Abstract: An auxiliary modular oven assembly for use with a gas chromatograph. The auxiliary oven assembly is comprised of a housing, an oven compartment, a heater, at least one sampling valve, at least one fixed volume sample loop, and at least one chromatograph column or column trains, wherein the column or column trains contains a material capable of causing the separation of chemical components of a chemical sample at elevated temperatures.

Abstract: An ion mobility spectrometer with a GC column and an internal circulation system is provided which can be used in trace gas analysis. Due to the special design of the gas circulation, the parameters: carrier gas velocity in the GC column, the flow rate of the gas to be analyzed and the flow rate of the drift gas can be varied extensively independently and without reaction. Additional pumps and gas splitters are arranged in the circulation system for this purpose.

Abstract: The invention is a gas chromatograph that includes a mechanism to heat the carrier gas to a temperature higher than that of the columns through which it flows. The carrier gas may be temperature programmed to achieve much the same results as the known technique of temperature programming the column.

Abstract: In a method of analyzing a sample, an internal pressure of a sample chamber is maintained at a predetermined level through a control valve. When the sample is injected into the sample chamber, the control valve is held at an opening degree before the sample is injected into the sample chamber for a predetermined period of time. Thus, a substantial amount of the sample injected to the sample chamber can be sent to a detector without loosing through the control valve.

Abstract: A method for detecting substances or mixtures of substances within a sample in an apparatus for comprehensive two-dimensional gas-chromatographic analysis according to the present invention, comprising the steps of:

Abstract: An on-line process gas chromatograph is provided which includes carrier gas flow components that control carrier gas flow through a gas chromatograph oven maintained at an elevated temperature. The carrier gas flow components are disposed relative to the gas chromatograph oven such that they are not subject to the temperatures present within the oven itself.

Abstract: Gas chromatographs of the invention generally comprise four or more analysis channels. Specifically, four or more gas chromatography columns are configured for parallel analysis of four or more gaseous samples with detection being effected using a microdetector array comprising four or more microdetectors. In one embodiment, the four or more microdetectors 510 are microfabricated detectors, and are integrally formed with a substrate or with one or more microchip bodies mounted on a substrate. In a preferred embodiment, a microdetector array comprises four or more thermal conductivity detectors having one or more thin-film detection filaments. A preferred heated environment for highly parallel gas chromatographs is also disclosed.

Abstract: The present invention herein relates to a sample injection device for micro gas chromatograph is assembled from five layers of thin plates and membrane. The first layer serves as cover plate and interfacial connection to outside columns. The second layer is fabricated with a sample channel and a carrier gas inlet split into an analytical channel and a reference gas channel, and two valve seats. The third layer is a flexible diaphragm for valve actuation. The fourth layer is fabricated with a pressurizing gas inlet hole and pressurizing channel leading to the diaphragms of valve seats. The fifth layer serves as another cover plate. An external solenoid valve is used to control the processes of sampling and injection. The channels and valve seats on each layer plate can be fabricated through several well-developed fabrication techniques such as photolithographic, LIGA processes or precision micro machining. All five layers are properly aligned and bonded by adhesives.

Abstract: An exhaust gas sensor includes a housing and a sensor element supported by the housing. The sensor element includes a support member having an exhaust side, a reference side, and an aperture extending through the support member between the exhaust side and the reference side. The sensor element further includes an exhaust-side electrode on the exhaust side of the support member. The exhaust-side electrode is electrically connected to a contact on the reference side of the support member via a lead extending through the aperture. The aperture is sealed around the lead such that gas cannot pass through the aperture. The support member is oriented substantially parallel to the flow of exhaust gases when the exhaust gas sensor is installed on a vehicle. The sensor further includes a contact pin in the housing that engages the contact and biases the sensor element against a portion of the housing.

Abstract: A gas chromatography system having a computer-controlled pressure controller that delivers pressurized pulses to a column junction point of two series-coupled columns having different stationary-phase chemistries and a method of using the same. Each pressurized pulse causes a differential change in the carrier gas velocities in the two columns, which lasts for the duration of the pressurized pulse. Whereby, the pressurized pulse selectively increases the separation of a component pair that exhibits separation at the exit of the first column, but otherwise co-elutes from the column ensemble.

Abstract: A gas chromatography system having a computer-controlled venting valve system that delivers pressurized pulses to a column junction point of two series-coupled columns having different stationary-phase chemistries and a method of using the same. Each pressurized pulse causes a differential change in the carrier gas velocities in the two columns, which lasts for the duration of the pressurized pulse. Whereby, the pressurized pulse selectively increases the separation of a component pair that exhibits separation at the exit of the first column, but otherwise co-elutes from the column ensemble.

Abstract: Gas chromatographs of the invention generally comprise four or more analysis channels. Specifically, four or more gas chromatography columns are configured for parallel analysis of four or more gaseous samples with detection being effected using a microdetector array comprising four or more microdetectors. In one embodiment, the four or more microdetectors 510 are microfabricated detectors, and are integrally formed with a substrate or with one or more microchip bodies mounted on a substrate. In a preferred embodiment, a microdetector array comprises four or more thermal conductivity detectors having one or more thin-film detection filaments. A preferred heated environment for highly parallel gas chromatographs is also disclosed.

Abstract: A gas chromatography system having a computer-controlled venting valve system that delivers pressurized pulses to a column junction point of two series-coupled columns having different stationary-phase chemistries and a method of using the same. Each pressurized pulse causes a differential change in the carrier gas velocities in the two columns, which lasts for the duration of the pressurized pulse. Whereby, the pressurized pulse selectively increases the separation of a component pair that exhibits separation at the exit of the first column, but otherwise co-elutes from the column ensemble.

Abstract: A coupling device connecting the output of a microchromatograph (&mgr;CG) to the input of a mass spectrometer (SM), said coupling device comprising a capillary tube with one end connected in sealed fashion to the source under vacuum of the mass spectrometer through the intermediary of an interface device, and with the other end connected to the output of the microchromatograph, in slack fashion, open to the atmosphere; the length and the diameter of the capillary tube being chosen such that the flow rate inside the capillary tube is very close to the flow rate at the output from the microchromatograph; the interface device being, furthermore, provided with heating means for very precise adjustment of the flow rate registered by the capillary.

Abstract: The present invention is a sample valve for use in conjunction with a gas chromatograph. The sample valve design provides for both the inertness and low permeability performance of a diaphragm, and an elastomeric material to apply adequate sealing pressure to the diaphragm to seal with the mating surface of a center plate of the sample valve. This valve design allows the active sealing surface to be well polished without the previous concern for maintaining critical flatness of the mating surfaces of the machined parts.

Abstract: The present invention relates to an autosampler device useful in high pressure liquid chromatography (HPLC), and more particularly to a device useful for the automated introduction of small sample volumes into a HPLC system. Methods of analyzing low abundant protein samples using such a device are also included.

Abstract: The invention is a device and method in a high-pressure chromatography system, such as a supercritical fluid chromatography (SFC) system, that uses a pump as a pressure source for precision pumping of a compressible fluid. The preferred exemplary embodiment comprises a pressure regulation assembly installed downstream from a compressible fluid pump but prior to combining the compressible flow with a relatively incompressible modifier flow stream. The present invention allows the replacement of an high-grade SFC pump in the compressible fluid flow stream with an inexpensive and imprecise pump. The imprecise pump becomes capable of moving the compressible fluid flow stream in a precise flow rate and pattern. The assembly dampens the damaging effects of an imprecise pump, such as large pressure oscillations caused by flow ripples and noisy pressure signals that do not meet precise SFC pumping requirements.

Abstract: A system for concentrating a volatile organic compound (VOC) sample uses in one embodiment a bypass line and a valve coupled thereto to regulate an amount of carrier gas flowing through a carrier gas line. A flow splitter fluidly couples the bypass line to the carrier gas line, and connects to the output of a cryofocuser. The valve opens at the onset of transferring the VOC sample from a concentrator trap such as a sorbent trap to the cryofocuser, thereby resulting in an increased amount of carrier gas flow between the concentrator trap and the cryofocuser for more efficient desorbing of the concentrator trap. The valve is closed when the focused VOC sample is flushed out of the cryofocuser for delivery to a gas chromatograph, preferably delivering the entire VOC sample to the GC.

Abstract: A planar manifold that integrates all the control pneumatics, electronic pressure controls (EPC), and injector inlet onto a single plate, therefore eliminating numerous seals, fittings and transfer tubing between these devices. The planar manifold utilizes plates of specific geometry that minimizes heat transfer between the heated components and the unheated components in the planar manifold, while maintains the mechanical rigidity to support the attached components during shock and vibration. The planar manifold not only improves the reliability and manufacturability of micro gas chromatographs, but also lowers the cost of production.

Abstract: An inlet system is used in conjunction with a standard gas chromatograph/mass spectrometer to facilitate the analysis of volatile components of substances fired from inkjet pens. The system allows for the investigation of changes in the ink resulting from resistor firing. In addition, the system can be used as a diagnostic tool to detect failures in individual firing chamber. After a block is cooled with liquid nitrogen, an analyte sample of ink is deposited on a stage in a chamber in the block and the chamber is then sealed. The stage is then heated vaporizing a portion of the analyte sample. A transfer gas passes over the stage and mixes with vaporized analyte. The mixture then enters a gas chromatography mass spectrometer which determines the analyte sample's components and relative amounts thereof.

Abstract: A gas chromatograph includes a control unit. The control unit normally operates such that a pressure sensor monitors an internal pressure of a sample vaporization chamber, and gas is discharged through a split path based on the internal pressure, thereby maintaining the internal pressure constant. When a large quantity of a sample is quickly injected and the internal pressure of the sample vaporization chamber exceeds a preset threshold value, the control unit shuts off for a predetermined time a control valve to lock at an opening degree right before the shut-off. Therefore, it is possible to minimize an amount of the sample released through the control valve.

Abstract: A microfluidic system is provided for separating components of many fluid samples in a parallel fashion through an array of capillary conduits. The system includes capillary conduits for receiving fluid samples, and for effecting separation of substituents of the sample by passing the sample through a corresponding array of capillary separation conduits containing a solid separation medium. The microfluidic circuit is made of three or more substrate layers and preferably includes etched channels in different layers that are dimensioned relative to one another to provide for retaining the solid composition within the capillary separation conduits. The system also includes an array of detector flow cells in fluid communication with the capillary separation conduits, and an array of high pressure connectors for connecting discrete capillary tubes to the fluid passages in the microfluidic circuit for introducing and removing the fluid samples from the system.

Abstract: A gas chromatography system having a computer-controlled pressure controller that delivers pressurized pulses to a column junction point of two series-coupled columns having different stationary-phase chemistries and a method of using the same. Each pressurized pulse causes a differential change in the carrier gas velocities in the two columns, which lasts for the duration of the pressurized pulse. Whereby, the pressurized pulse selectively increases the separation of a component pair that exhibits separation at the exit of the first column, but otherwise co-elutes from the column ensemble.

Abstract: A micro-machined back-flush injector that allows for a sample introduced into the injector to be properly injected into a gas chromatography apparatus in a short time period of between 10 and 100 milliseconds. A micro-machined injector having back-flushing capability that allows back-purging of unwanted components in the device and provides clean-up of channels in contact with the sample. Further, a method of operating an injector such that a sample is properly injected and purged from the system to which the injector is operably attached.

Abstract: A novel gas chromatograph includes suitably located backpressure restrictors. In a preferred embodiment, each backpressure restrictor consists of capillary tubing with a pressure drop across it controlled to be less than or slightly greater than 0.528. One embodiment places the backpressure restrictor upstream of an initial stream switching valve and downstream of sample pre-heat coil. Another embodiment places the backpressure restrictor downstream of the gas chromatograph's measurement element and its carrier pre-heat coil. In each case, only a controlled and predictable flow rate is achieved, both regulating the flow rate through the system and back pressuring fluid to remain in the respective pre-heat coils to achieve ideal temperature.

Abstract: There is provided a gas analyzing apparatus capable of minimizing gas remaining by integrating gas switching apparatuses into one and capable of analyzing impurities of ppb level to sub-ppb level contained in various kinds of high-purity gases efficiently and accurately.

Abstract: In a catalytic sensor, a bead is located within a can having an aperture in its front surface. The bead is surrounded by thermally insulating material such as glass fiber and a filter material is arranged between the bead and the aperture in the can. This acts to remove H2S or other inhibiting gases before they reach the bead and impair its performance. The thermally insulating material allows the filter material to be included whilst still permitting the bead to be operated at a high temperature.

Abstract: Described is apparatus and a process for collecting for subsequent analysis a volatile composition such as a perfume composition located on the surface and/or in the interstices of a planar pliable porous substrate such as a towel section. A planar surface of the substrate which contains the volatile composition is initially juxtaposed adjacent a solid wall (e.g., glass frit) porous to a nonreactive carrier gas such as air, nitrogen or carbon dioxide, and fully and tightly covers the porous section of the wall. The carrier gas is passed through the porous section of the wall and then through the pliable porous substrate section which is adjacent to the wall; after which the carrier gas contains each component of the volatile composition. The composition-carrier gas mixture is then passed through a trapping substance (e.g., TENAX® a polyphenylene oxide) which entraps the molecules of each component of the volatile composition. The thus-collected volatile composition may be subsequently analyzed (e.g.

Abstract: A chromatography detection system can handle the flow from a chromatography column. The chromatography detection system has an injection valve and a detector for detecting emissions from a flowing sample. The injection valve has at least one loop and is adapted to connect to the chromatography column. The valve can (a) load the at least one loop independently of the chromatography column in a first mode, and (b) serially connect the least one loop between the chromatography column and the detector in a second mode. Thus, flow from the at least one loop to the detector is driven by eluate from the chromatography column.

Abstract: The present disclosure relates to a gas chromatograph having a plurality of layers or channels. The chromatograph typically comprises an inlet that receives a sample to be analyzed, a column disposed in each of the plurality of chromatograph layers, each column being in fluid communication with and downstream from the inlet and having a stationary phase coating its inner surfaces, and a detector in fluid communication with and downstream from at least one of the columns. In a preferred arrangement, the chromatograph includes a pre-column disposed in each of the chromatograph layers upstream of the columns, each pre-column being in fluid communication with the inlet and having a stationary phase coating its inner surfaces.

Abstract: A sample gas is introduced into a collecting pipe filled with a collecting agent to collect odor components therein, and a gas, such as nitrogen gas, is introduced into the collecting pipe to remove moisture and so on. Then, a heater is heated to raise a temperature of the collecting pipe so that a part of the odor components adsorbed by the collecting agent is separated therefrom, and then, a carrier gas is supplied to the collecting pipe to send the separated odor components to a sensor. After a predetermined time has passed, the heater is further heated to send the separated odor components to the sensor. The heater may be further increased. Thus, an output information of the gas sensor in one cycle of measurement can be increased.

Abstract: Described is apparatus and a process for collection for subsequent analysis a volatile composition such as a perfume composition located on the surface and/or in the interstices of a planar pliable porous substrate such as a towel section. A planar surface of the substrate which contains the volatile composition is initially juxtaposed adjacent a solid wall (e.g., glass frit) porous to a nonreactive carrier gas such as air, nitrogen or carbon dioxide, and fully and tightly covers the porous section of the wall. The carrier gas is passed through the porous section of the wall and then through the pliable porous substrate section which is adjacent to the wall; after which the carrier gas contains each component of the volatile composition. The composition-carrier gas mixture is then passed through a trapping substance (e.g., TENAX®) which entraps the molecules of each component of the volatile composition. The thus-collected volatile composition may subsequently be analyzed (e.g.

Abstract: Inverse gas-chromatography apparatus for investigating the properties of a solid material, having a carrier fluid, comprising at least two fluid components (typically water and an inert gas); a second flow comprising the carrier fluid components and probe material; a temperature controlled column, for holding the solid material; a switch for selectively passing the flow of carrier fluid and the second fluid flow through the column; a detector for detecting the passage of the probe material through the column. The relative proportions of the fluid components in the flow of carrier fluid and the second fluid flow can be controlled.

Abstract: A planar manifold that integrates all the control pneumatics, electronic pressure controls (EPC), and injector inlet onto a single plate, therefore eliminating numerous seals, fittings and transfer tubing between these devices. The planar manifold utilizes plates of specific geometry that minimizes heat transfer between the heated components and the unheated components in the planar manifold, while maintains the mechanical rigidity to support the attached components during shock and vibration. The planar manifold not only improves the reliability and manufacturability of micro gas chromatographs, but also lowers the cost of production.

Abstract: A micro-machined back-flush injector that allows for a sample introduced into the injector to be properly injected into a gas chromatography apparatus in a short time period of between 10 and 100 milliseconds. A micro-machined injector having back-flushing capability that allows back-purging of unwanted components in the device and provides clean-up of channels in contact with the sample. Further, a method of operating an injector such that a sample is properly injected and purged from the system to which the injector is operably attached.

Abstract: An apparatus and method for selectively concentrating an analyte on an apparatus by evaporating solvent from the analyte. Concentration is performed by heating or by flowing a gas stream over the analyte to evaporate solvent from the analyte. The invention also provides a method to be used in conjunction with the apparatus.

Abstract: A novel gas chromatograph includes suitably located backpressure restrictors. In a preferred embodiment, each backpressure restrictor consists of capillary tubing with a pressure drop across it controlled to be less than or slightly greater than 0.528. One embodiment places the backpressure restrictor upstream of an initial stream switching valve and downstream of sample pre-heat coil. Another embodiment places the backpressure restrictor downstream of the gas chromatograph's measurement element and its carrier pre-heat coil. In each case, only a controlled and predictable flow rate is achieved, both regulating the flow rate through the system and back pressuring fluid to remain in the respective pre-heat coils to achieve ideal temperature.

Abstract: There are provided a method and an apparatus capable of accurately analyzing impurity component having high adsorptivity or reactivity in a short time. Prior to starting measurement, predetermined amount of sample gas is introduced into analyzing system in plural times with predetermined time interval and then, analysis of impurities is started.

Abstract: The invention relates to a method of trace analysis of organic compounds which calls for the steps of setting a test piece in a flow cell, and thereafter removing organic compounds from the test piece by heating it at high temperature in an oven. The compounds are concentrated in a trap tube and then removed from the trap tube and carried into a concentrating/inlet unit, such as a thermal desorption cold trap injector. In this unit, cryofocusing of the compounds is performed, and then the organic compounds are introduced into a gas chromatograph to be analyzed therein, wherein a part of the purified inert gas is caused, except during the process of trapping the organic compounds, to flow into the flow cell from the direction opposite the direction from which the gas flows along the trapping line.

Abstract: A multiport, diaphragm sealed valve suitable for use as both a sampling and column switching valve. The valve is constructed to internally block fluid communication between one or more pairs of ports in a valve operating mode. Such blocking may be used to conserve carrier gas when the valve is in the ON position.

Abstract: There is provided a gas analyzing apparatus capable of minimizing gas remaining by integrating gas switching apparatuses into one and capable of analyzing impurities of ppb level to sub-ppb level contained in various kinds of high-purity gases efficiently and accurately.