Abstract: Disclosed are systems and methods that include providing a vessel having an inlet and an outlet for communicating a carrier gas through the vessel; determining a differential pressure between the inlet and the outlet for a known flow rate at the outlet; and, determining a unit flow per unit pressure based on a ratio of the flow rate and the differential pressure. In certain embodiments, the flow rate at the outlet is established by controlling the flow rate of the gas. In some embodiments, the methods and systems can include a viscosity in the ratio, determining a flow rate at ambient pressure using a factor based on a ratio of a gas pressure at the output and ambient pressure, and/or, determining a flow rate at ambient temperature using a factor based on a ratio of a temperature at the output and ambient temperature.

Abstract: The present invention generally relates to electrochemical systems for producing hydrogen and/or power. Various aspects of the invention are directed to reactor designs for producing hydrogen and/or power from a fuel and water, conducting ceramics and other materials for such systems, including mixed ionically and electrically conducting ceramics which can be used for hydrogen gas generation, control systems for such systems, and methods of operating such systems.

Abstract: A method for obtaining reproducibility of the retention times of the components of a mixture to be analysed in an apparatus for gaschromatographic analysis provided with a capillary column, when there occurs one of the following variations: variation in the length of the column, or alternatively its replacement with a column having identical real specifications with the exception of the length, and/or variation in the pressure of the carrier gas at output from said column. The method envisages that the pneumatic resistance of the column is known and preferably measured before and after the aforesaid variations, and that a new input pressure or a new mass flow of the carrier gas will be entered into said apparatus for gaschromatographic analysis in relation to said values of pneumatic resistance.

Abstract: An apparatus, system, and method are disclosed for broad spectrum chemical detection. The method includes detecting an ambient temperature and setting a target temperature based on the ambient temperature. The target temperature is a temperature greater than the ambient temperature. The method further includes determining elution data for the target temperature, either by selecting a target temperature at which elution data is available, or by interpolating between available sets of elution data. The method includes setting a preferred target temperature when an external power source is available, when faster sensor response is desired, and when higher resolution data is desired. The method further includes controlling the temperature of gas chromatography (GC) columns within a GC sensor to the target temperature.

Abstract: A hand-held, ultra-sensitive gas chromatograph which provides real time detection and analysis of chemical compounds or impurities is disclosed. The detection sensitivity ranges from parts per trillion to parts per million with an average retention time ranging from thirty to forty-five seconds. Optimum calculated effective plate number is 55,000, with a response time on the order of two minutes. The self-contained apparatus operates on twenty-four watts, weighs twelve pounds, and measures 8?×6?×13.

Abstract: An automated system for processing a liquid test sample is provided.

Abstract: Chromatography column assembly of the direct heating type, comprising at least a capillary column, at least a tubular structure which envelops the capillary column and is coaxial with it, means to directly heat the column, means to detect the temperature of the column and one or more electrically insulating covering elements, wherein the tubular structure comprises a plurality of tubular meshes each formed of a plurality of filaments woven together (FIG. 3).

Abstract: Disclosed are systems and methods that include providing a vessel having an adsorbent disposed therein, the vessel having an inlet and an outlet for communicating a carrier gas through the vessel; determining a differential pressure between the inlet and the outlet for a known flow rate at the outlet; and, determining a geometric measure for the vessel based on a ratio of the known flow rate and the differential pressure. In some embodiments, the methods and systems can include a viscosity in the ratio, determining a flow rate at ambient pressure using a factor based on a ratio of a gas pressure at the output and ambient pressure, and/or, determining a flow rate at ambient temperature using a factor based on a ratio of a temperature at the output and ambient temperature.

Abstract: The preparative liquid chromatograph uses a plurality of detectors including a mass spectrometer, and a chromatogram generator is provided for generating a plurality of chromatograms each corresponding to each of the plurality of detectors. The plurality of chromatograms are converted into a respective binary signal by comparing the chromatogram with a predetermined threshold, and a logical operator performs a binary operation on the plurality of respective binary signals, whereby a resultant binary signal is generated. A separation controller controls the fraction collector of the preparative liquid chromatograph based on the resultant binary signal to separate components from a sample. When “AND” is used as the binary operation, the resultant binary signal is “1” only when all the respective binary signals are “1”. This assures a high precision, high purity separation where an impurity mingling is minimized.

Abstract: An electronically controlled back pressure regulator comprises an analysis device having a vent coupled to the analysis device through a vent path, a pressure sensor coupled to the vent path, a proportional valve coupled to the vent path, the proportional valve configured to controllably alter pressure in the analysis device, and an electronically controlled closed-loop controller configured to control a flow through the vent based on a signal from the pressure sensor and an electronically controlled pressure setpoint.

Abstract: A fluidic switching device is particularly for use in chromatography is described. The device allows a rapid switching between chromatographic columns; particularly, in gas chromatography.

Abstract: A microfabricated mass-sensitive chemical preconcentrator actively measures the mass of a sample on an acoustic microbalance during the collection process. The microbalance comprises a chemically sensitive interface for collecting the sample thereon and an acoustic-based physical transducer that provides an electrical output that is proportional to the mass of the collected sample. The acoustic microbalance preferably comprises a pivot plate resonator. A resistive heating element can be disposed on the chemically sensitive interface to rapidly heat and release the collected sample for further analysis. Therefore, the mass-sensitive chemical preconcentrator can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

Abstract: Devices for enhancing the sensitivity of a microsensor or any other micro device by providing on-line preconcentration. Microconcentrators that can be integrated with a sensor or a micromachined GC to enhance the signal to noise ratio can include a miniaturized sorbent trap fabricated on a microchip. The microconcentrator can be made on a silicon substrate so that a sensor can be integrated on the same chip. The microconcentrator is composed of at least one microchannel lined with a microheater for in-situ heating. Preconcentration may be achieved on a thin-film polymeric layer deposited above the heater in the microchannel. Rapid heating by the channel heater generates a “desorption pulse” to be injected into a detector or a sensor.

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: An oxygen separator for separating oxygen from ambient air utilizing a vacuum swing adsorption process has a mass of less than 2.3 kg. A carrier is mountable on a person to support the oxygen separator for ambulatory use.

Abstract: A purge and trap concentrator and a method for drying a stream of sample gas in a gas analysis instrument. A dryer tube has an inlet that receives a stream of sample gas during a drying interval and receives a stream of dry gas during a regeneration interval. The dryer tube also has an outlet and an interior passageway between the inlet and an outlet. Support material comprising polymer sorbent is placed in the interior passageway and provides a support surface area for a hygroscopic coating comprising lithium chloride. A controller controls a heater to increase the temperature of the dryer tube to between 100 and 300 degrees centigrade during the regeneration interval and controls the heater to decrease the temperature of the dryer tube to below 100 degrees centigrade during the drying interval.

Abstract: An apparatus and method are disclosed to detect foam above a liquid sample in a sparge vessel, and disrupt any foam that may exist. The foam sensor includes an optical emitter and optical sensor coupled to a sparge vessel above the level of the liquid sample. Foam is detected if the light beam is attenuated or blocked. The foam disrupter provides thermal energy to raise the temperature of a surface in the sparge vessel to break up the foam, which may condense on the walls of the sparge vessel.

Abstract: This invention relates to a modulator for use in gas chromatographic analysis, adopted for alternatively trapping and releasing fractions of solutes in a length of a capillary column within a chromatographic oven, characterized in that it comprises at least one nozzle placed to spray at least one jet in at least one corresponding place along said capillary column length, said nozzle(s) being connected each to a source of liquid CO2 via a related valve, and means for alternatively opening said valve(s) for a predetermined time, to cause a jet of liquid CO2 to impinge for said predetermined time on said column place and to leave the oven atmosphere to heat said column place after said predetermined time. The modulator can be used in a conventional GC system or in a two dimensional GC system, for modulating the analytes fed to the second capillary column.

Abstract: An apparatus and method are disclosed to detect foam above a liquid sample in a sparge vessel, and disrupt any foam that may exist. The foam sensor includes an optical emitter and optical sensor coupled to a sparge vessel above the level of the liquid sample. Foam is detected if the light beam is attenuated or blocked. The foam disrupter provides thermal energy to raise the temperature of a surface in the sparge vessel to break up the foam, which may condense on the walls of the sparge vessel.

Abstract: A method and an apparatus for sample injection in gas chromatography increases the injecting volume of a sample, and can analyze any of high-boiling-point compounds, low-compounds boiling-point compounds, and compounds decomposed by heat. A sample is injected into a vaporizing chamber 6 having curved or crooked outer wall 6G and sample path S and formed of continuous inner walls 6H; the sample is temporarily held in the vaporizing chamber 6; then an objective compound is vaporized, and introduced into a separation column 17.

Abstract: A sub- to super-ambient temperature programmable microfabricated gas chromatography column enables more efficient chemical separation of chemical analytes in a gas mixture by combining a thermoelectric cooler and temperature sensing on the microfabricated column. Sub-ambient temperature programming enables the efficient separation of volatile organic compounds and super-ambient temperature programming enables the elution of less volatile analytes within a reasonable time. The small heat capacity and thermal isolation of the microfabricated column improves the thermal time response and power consumption, both important factors for portable microanalytical systems.

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: 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 temperature programmable microfabricated gas chromatography column enables more efficient chemical separation of chemical analytes in a gas mixture by the integration of a resistive heating element and temperature sensing on the microfabricated column. Additionally, means are provided to thermally isolate the heated column from their surroundings. The small heat capacity and thermal isolation of the microfabricated column improves the thermal time response and power consumption, both important factors for portable microanalytical systems.

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 method and an apparatus for chromatography are described, wherein at least one element in electrically conductive material is provided to heat the capillary column in a direct way and wherein the control of the temperature is carried out according to a mathematical model having a component of predictive type, or Feed Forward type, that describes the thermodynamic behavior of the assembly comprising the electrically conductive element and the column at least as a function of the thermal resistance and the thermal capacity of the assembly thus constituted in order to regulate the supply of electrical power supplied to the conductive element.

Abstract: A thermal conductivity detector includes not only a thermal conductivity detector cell disposed so as to be heated by heat transmitted from a first heater block and a column connector connected to the detector cell and to a column of a chromatograph but also a second heater block for heating the column connector. The heaters for individually heating these two heater blocks are controlled simultaneously and in synchronism by a single temperature controller according to the temperature of the first heater block for heating the detector cell.

Abstract: A chemical preconcentrator with integral thermal flow sensor can be used to accurately measure fluid flow rate in a microanalytical system. The thermal flow sensor can be operated in either constant temperature or constant power mode and variants thereof. The chemical preconcentrator with integral thermal flow sensor can be fabricated with the same MEMS technology as the rest of the microanlaytical system. Because of its low heat capacity, low-loss, and small size, the chemical preconcentrator with integral thermal flow sensor is fast and efficient enough to be used in battery-powered, portable microanalytical systems.

Abstract: Capillary column oxidation in gas chromatography systems, particularly of polyimide clad columns, is a major cause of column failure and it limits the maximum temperature at which columns can be used. A gas chromatography column oven system is described which utilizes inert gas to substantially eliminate column oxidation thereby increasing column thermal stability. These column oven systems thus increase column lifetime and maximum operating temperature. The column oven systems comprise pneumatically sealed oven enclosures with sealed access ports, sealed sample line ports, and inlet and outlet gas ports to which are connected an inert gas supply and an exhaust gas control system respectively.

Abstract: A gas chromatography system with suspended tubular separation column(s) in an enclosed convection oven where a gas medium is heated by at least two electrically powered heaters. A kit to modify gas chromatographic ovens for operation with at least two electrically powered heaters. The heaters are positioned to promote even heating along the length of the column(s) and shielding of the column(s) from radiant heat. The heaters can provide faster heating rates at elevated temperatures.

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: To switch gas flows between gas sources and gas sinks, a gas flow switching device includes gas passages, which communicate with one another and which have connecting points for the gas sources and the gas sinks. Furthermore, the gas flow switching device has a device for setting different pressures. To simplify the construction of the gas flow switching device and to achieve precisely defined pressure and flow conditions without the need for calibration, the gas flow switching device has two plates (9, 10), which are positioned on top of one another and joined together. The two plates (9, 10) have congruent channels (11) on their respective sides that face one another. These channels (11) have semicircular cross sections and form gas passages (4 to 8). In addition, at their lateral exit points from the plates (9, 10), the channels (11) form connecting points (12 to 17).

Abstract: To switch gas flows between gas sources and gas sinks, a gas flow switching device includes gas passages, which communicate with one another and which have connecting points for the gas sources and the gas sinks. Furthermore, the gas flow switching device has a device for setting different pressures. To simplify the construction of the gas flow switching device and to achieve precisely defined pressure and flow conditions without the need for calibration, the gas flow switching device has two plates (9, 10), which are positioned on top of one another and joined together. The two plates (9, 10) have congruent channels (11) on their respective sides that face one another. These channels (11) have semicircular cross sections and form gas passages (4 to 8). In addition, at their lateral exit points from the plates (9, 10), the channels (11) form connecting points (12 to 17).

Abstract: A multiple parallel hand-held gas chromatograph (GC) system which includes several independent GCs. Each independent GC has its own injector, separation column, detector and oven and the GCs are mounted in a light weight hand-held assembly. Each GC operates independently and simultaneously. Because of different coatings in different separation columns, different retention times for the same gas will be measured. Thus, for a GC system with multiple parallel GCs, the system can measure, in a short period, different retention times and provide a cross-reference in the determination of the measured gas and to become a two-dimensional system for direct field use.

Abstract: A chromatograph includes an inlet for receiving a sample and a pressurized hydrogen gas 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 detector for receiving the effluent stream and for providing a detector output stream; and a gas storage system for receiving the detector output stream (and optionally a split flow and a septum purge flow in the instance of a split/splitless inlet) and for storing the received gas stream for subsequent reuse. In the preferred embodiment of the gas storage system, a plurality of metal hydride storage (MHS) systems are used.

Abstract: Energy efficiency of a thermal zone in an analytical instrument is improved by use of an oven housing module having an enclosure body defining an oven cavity, wherein the enclosure body exhibits a size and shape sufficient to receive a component to be subjected to temperature control within a thermal zone located in the oven cavity. A temperature control assembly includes a vent assembly communicating with ambient air, a fan, and a fast cooling flap, wherein the temperature of the thermal zone may be modulated by supplementing the oven cavity air with ambient air. The fast cooling flap may be operated for opening one side of the oven cavity to ambient conditions such that ambient air may be rapidly introduced to the oven cavity and the cavity air may be rapidly exhausted from the oven cavity for rapid cooling of the thermal zone.

Abstract: A system for analysis of vapor constituents in a gaseous and/or liquid media includes an analyzing gas chromatographic unit, an in-line preconcentrator assembly having a trap housing, an adsorbent material received in the trap housing, and a transfer line unit couplable to the trap housing and directly connected to the analyzing unit. Carrier mechanism drives the trap housing with respect to the transfer line unit linearly or along an arc trajectory. When the trap housing is displaced from the transfer line unit, the media surrounding the trap housing is forced inside of the trap housing by a pump and vapor constituents are adsorbed on the adsorbent material within the trap housing. When the trap housing is moved in pressure tight engagement with the transfer line unit, the adsorbent material is heated to release the vapor constituents from the adsorbent material.

Abstract: A chromatograph includes an inlet 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 detector for receiving the effluent stream and for providing a detector output stream; and a gas recycling system for receiving the detector output stream, and optionally a split flow and a septum purge line flow, and for providing therefrom a recycled carrier gas stream suitable for reuse as the pressurized carrier fluid flow.

Abstract: A chromatograph includes an inlet for receiving a sample and a pressurized hydrogen gas 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 detector for receiving the effluent stream and for providing a detector output stream; and a gas storage system for receiving the detector output stream (and optionally a split flow and a septum purge flow in the instance of a split/splitless inlet) and for storing the received gas stream for subsequent reuse. In the preferred embodiments of the gas storage system, a plurality of metal hydride storage (MHS) systems are used.

Abstract: The present invention provides an improved method for calculating and adjusting the column head pressure of a GC instrument based on the column's plate capacity, N.sub.c, and film thickness, d.sub.s, measured ideally during the manufacturing process and identified with the column such that software associated with the GC instrument can calculate a new column head pressure based on the relationship between the plate capacity and film thickness of the existing column to the plate capacity and film thickness of the new or shortened column. The column head pressure of the GC is adjusted to the new column head pressure to provide a reduction in the column-to-column non-reproducibility error in retention times of all peaks.

Abstract: An apparatus and a method are described for forming a chemical modulation of a substance present in a fluid stream, which utilize a movable device, such as a movable heater, to induce changes in the retention of a chemical substance flowing through the modulator tube. The modulator tube has an inlet, a first portion in communication with the inlet, a second portion in communication with said first portion, and an outlet in communication with said second portion. The method involves causing a chemical modulation by moving retention alteration device relative to a modulator tube.

Abstract: An injector for a gas chromatography system resistively heats an included cold trap by magnetically inducing a high-frequency current therethrough to inject absorbed analyte into a gas chromatography separation column. The injector includes a flow controller that is set initially to load analyte into the trap. A heater and a two-stage Peltier cooler are used to establish a sharp trough-shaped temperature gradient along the cold trap so that analyte loaded into the cold trap is absorbed only at a relatively cold "focussing" zone of the trap. Once the analyte is focussed, the flow controller is set to direct released analyte into the column. The magnetic-field generator includes a capacitor that is discharged to initiate cold-trap heating. An inverter converts the discharge to a 100,000 Hz waveform through a transformer primary coil. A magnetic core delivers the resulting alternating magnetic field through the cold trap.

Abstract: A gas chromatograph includes a carrier gas supply flow path to which a pressure sensor, resistance tube, and control valve are sequentially connected. A differential pressure sensor is situated on both sides of the resistance tube to measure the differential pressure. The control valve is controlled by a controlling portion through signals from the pressure sensor and differential pressure sensor to control a flow rate of a carrier gas. Thus, in the gas chromatograph, the flow rate of the carrier gas can be controlled without an expensive pressure regulator, and a pressure of the carrier gas to be supplied can be selected as desired.

Abstract: A gas chromatograph has a sample vaporization chamber connected to a column for vaporizing a liquid sample injected therein and introducing this vaporized liquid sample with a carrier gas into the column. There is also a flow rate control device for controlling the flow rate of the carrier gas either as it is being supplied into the vaporization chamber or as it is being discharged from the vaporization chamber through a discharge route other than the column for keeping the gas pressure approximately constant inside the vaporization chamber. A leakage detector detects a leakage of gas from the vaporization chamber on the basis of either a target value set for the flow rate control device or a monitored value of the flow rate. A warning device outputs a warning when a gas leakage is detected by the leakage detecting device.

Abstract: An apparatus and process for the continuous, near real-time monitoring of low-level concentrations of organic compounds in a liquid, and, more particularly, a water stream. A small liquid volume of flow from a liquid process stream containing organic compounds is diverted by an automated process to a heated vaporization capillary where the liquid volume is vaporized to a gas that flows to an automated gas chromatograph separation column to chromatographically separate the organic compounds. Organic compounds are detected and the information transmitted to a control system for use in process control. Concentrations of organic compounds less than one part per million are detected in less than one minute.

Abstract: A gas chromatograph and method of chromatography are provided. Analytes, those compounds to be tested, are extracted from the sample by moving the sample into a column which has a stationary phase along the column walls. The column has two sections which are different in length. The longer section is heated and the analytes move to the shorter section. The longer section is then cooled and the entire column is heated. The device then functions as an analytical column and the analytes move out of the shorter section, through the longer section, and out of the column. A detector placed at the end of the column's longer section detects the presence of the compounds as they exit the column. In an alternate embodiment two separate columns are provided. One column is used as the extraction column and the other is used as the analytical column.

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: A chemical sampling apparatus including an interface between a miniature mobility spectrometer and a gas chromatography system. The apparatus has a gas chromatography an ion mobility spectrometer and an input for inputting a regulated flow of a gas to be analyzed to the gas chromatograph. An interface is positioned between the gas chromatograph and the ion mobility spectrometer. The interface accepts and analyzes eluted gas from the gas chromatograph and selectively inputs the eluted gas to the ion mobility spectrometer only when an eluted gas condition to be analyzed is detected.