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 is directed to a method for multidimensional gas chromatography for separating the analytes of a complex sample. The method comprises the steps of introducing the sample onto a first column whereby the sample is separated into at least two segments, introducing at least one segment into a heartcut device whereby the segments are selectively separated into at least two heartcut fractions, introducing at least one of the fractions onto a second column whereby at least one fraction is further separated into at least two analytes, introducing at least one analyte from the second column to a gas chromatography connector, introducing the analyte from the connector to a third column, and introducing the analyte from the third column into a detector whereby the analyte is analyzed and identified.

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: An ion source includes structure having separate first and second ion volumes therein, and electron source structure having first and second portions that selectively supply electrons to the first and second ion volumes, respectively. The electron source structure has a first operational mode in which the second portion substantially prevents a supply of electrons to the second ion volume and in which electrons are supplied to the first ion volume under control of the first portion, and has a second operational mode in which the first portion substantially prevents a supply of electrons to the first ion volume and in which electrons are supplied to the second ion volume under control of the second portion.

Abstract: A modified liquid impingement unit is configured to automatically maintain a volume of buffer solution within a determined range, the buffer solution used to collect airborne particles from an impinging airflow. The liquid impingement unit includes a first end of an air nozzle and a first end of a vacuum tube sealed within collection vessel. A fluid delivery tube is positioned within the vacuum tube such that a first end of the fluid delivery tube is also positioned within the sealed collection vessel. External to the sealed collection vessel, the fluid delivery tube branches from the vacuum tube through an aperture in the vacuum tube. The vacuum tube is coupled to a vacuum pump and the fluid delivery tube is coupled to a fluid pump. A control module provides control signals to the fluid pump such that the fluid pump delivers a second volume of buffer solution from a buffer solution container to the collection vessel via the fluid delivery tube.

Abstract: A system for controlling the flow rate into a chromatographic column is disclosed generally comprising communicating a fluid to the column through a transfer line, measuring the inlet pressure, determining the outlet pressure, and adjusting the applied pressure until the inlet and outlet pressures produce a desired flow rate for the transfer line outlet. In certain embodiments, the applied pressure is adjusted by controlling a proportional valve. In some embodiments, the outlet pressure is determined by measuring the pressure drop across the transfer line and calculating the outlet pressure from the measured inlet pressure and the pressure drop.

Abstract: An analyte pre-concentrator for gas chromatography is disclosed generally comprising a tube packed with an adsorbent, wherein the tube may serve as the liner of a chromatographic injector, as an adsorbent trap coupled to a chromatographic column, and/or as an adsorbent trap coupled to a headspace sampler. Preferably, a heating device allows the tube to be heated. In a preferred embodiment, the analyte pre-concentrator further comprises a column isolating accessory so that a chromatographic column can be temporarily isolated from substances flowing through the tube.

Abstract: A method and apparatus for detecting a flow disruption within a gas chromatograph (GC) inlet. A controller controls an input flow of a gas entering a chamber of the GC inlet, and the output flow of gas leaving the chamber. A flow disruption is detected when at least one of the input and output flows deviates from a target value.

Abstract: Disclosed are systems and methods that include a thermal desorption unit, a chromatographic column, and an interface device between the unit and the column. The interface device controls the fluid flowing into the column, such as by providing additional carrier gas to maintain a substantially constant gas flow or velocity, by proving a controlled temperature increase, or by venting a portion of the gas received from the thermal desorption unit, thereby removing the dependence on the thermal desorption unit for such control. In some embodiments, the interface is a chromatographic injector. In certain embodiments, a transfer line from the desorption unit is coupled to the same port of the interface device as the chromatographic column. In some of these embodiments, this is accomplished by employing a special adaptor.

Abstract: The aim of the invention is to optimize the analysis of substances separated by gas chromatography with a gas chromatograph, comprising a separating device and a mass spectrometer situated down there from. To this end, a detector that detects the separated substances in a nondestructive manner is placed in-line between the output of the separating device and a controllable inlet valve of the mass spectrometer. An evaluating device situated down from the detector evaluates the detector signals and, based on the evaluation, controls the inlet valve for introducing predeterminable substances into the mass spectrometer.

Abstract: The present invention is directed to a gas chromatograph (GC) module having a column assembly and a printed circuit board mounted to a valve assembly. A plurality of electronic devices are mounted to the circuit board. The electronic devices include non-volatile memory, pressure sensors and detector devices.

Abstract: An apparatus and a method for separating a specified gas from a gas to be treated containing the specified gas comprising at least one ingredient, which comprises allowing the gas to be treated to flow through a column without the use of another gas for transferring the gas to be treated, while keeping the inside of the column packed with a packing material at a reduced pressure. The above apparatus and method can be suitably used for separating a specified gas having a high purity at a low cost.

Abstract: Embodiments of the present invention relate to detector structures for use in a micro gas analyzer, preferably in a differential setup. The detector structures may comprise one or more detector types, such as photo-ionization (PID), electron capture (ECD), ion mobility (IMS), differential mobility (DMS), ion-trap mass spectrometer (ITMS), in which all are provided with ions and electrons from one vacuum ultra violet (VUV) source. This source may also provide ions for ion-based gas pumps.

Abstract: Provided is a separating agent for enantiomeric isomers that is advantageous from the production standpoints of having a high enantiomeric resolution ability inherent in polysaccharide derivatives, solvent resistance, high solubility in a reaction solvent, and good filtration property. That is, the separating agent for enantiomeric isomers includes a polysaccharide oligomer derivative derived from a polysaccharide oligomer having a number-average degree of polymerization of from 5 to less than 50, supported on a carrier.

Abstract: A system for controlling the flow rate into a chromatographic column is disclosed generally comprising communicating a fluid to the column through a transfer line, measuring the transfer line inlet pressure, determining the transfer line outlet pressure, and adjusting the applied pressure until the inlet and outlet pressures produce a desired flow rate for the transfer line outlet. In certain embodiments, the applied pressure is adjusted by controlling a proportional valve. In some embodiments, the outlet pressure is determined by measuring the pressure difference across the transfer line and calculating the transfer line outlet pressure from the measured inlet pressure and the pressure difference.

Abstract: Processes for removing inorganic impurities from HCl-containing gases, which processes comprise: providing a crude gas stream comprising hydrogen chloride and at least one inorganic component; introducing the crude gas stream into an adsorber bed; adsorbing at least a portion of the at least one inorganic component from the crude gas stream on the adsorber bed to form a purified HCl gas, and removing the purified HCl gas from the adsorber bed.

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: An improved process for the separation of carbon dioxide from the flue gas of an oxy-combustion power plant is provided. The flue gas is compressed, cleaned, cooled and dried. This flue gas stream contains carbon dioxide and oxygen, and is sent to a column. This column may be a distillation column or a stripping column. This column separates the inlet stream into a top gas stream and a bottom liquid stream. The top gas from the column is combined with the inlet stream.

Abstract: An improved gas chromatograph system includes a radiant source, an insert located to receive an output of the radiant source, and an analytic column wound on a concave surface of the insert so that successive coils of the wound analytic column are in direct contact with each other and exert an outward pressure on the concave surface of the insert such that the outward pressure minimizes a gap between the analytic column and the concave surface of the insert so as to minimize thermal gradients and maximize heat transfer to the analytic column.

Abstract: The invention covers the mining industry. Detection method of the occurrence zone of the mantle substance diapir finger consisting in that that geological observation are carried out in riftzones banked up by diapirs of the abnormal mantle and places of location of the mantle substance finger in the earth's crust are determined. Based on the presence of influence traces of silanes streams upon the rock and/or presence of separate ridges having the length up to 200 km by the width of up to 20 km and/or based on the blast traces of silanes and/or presence of scoria cones, differing by that that the correspondence of 3He/4He from gases sampled from sources of 10?5 order is additionally determined for determination of silicides at the small depth as physical parameters for the location of the mantle substance diapir finger in the earth's crust. The presence of high semiconductor conductivity, locality and activity of magnetic anomalies and anomalies of gravity field is additionally established.

Abstract: The invention relates to a method for determining and controlling inorganic and/or organic deposits in a water system, preferably a paper and/or board machine re-circulation system. According to said method, one or more probes are introduced into the water system, then removed from said system after a pre-selected exposure period and prepared for surface analysis. The deposits that have accumulated on the probes are determined by means of microscopy methods and/or gas chromatography methods and/or mass spectrometry methods.

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: A single stage flow modulator for performing comprehensive chromatography comprises a first chromatographic column, a valve fluidically coupled to at least two fluid conduits, wherein when in a first position, the valve directs a control flow to direct an output of the first chromatographic column to a first detector, and wherein when in a second position, the valve directs a control flow to direct a portion of an output of the first chromatographic column to a second chromatographic column, wherein the portion of the output of the first chromatographic column directed to the second chromatographic column is continuously modulated throughout a sample run.

Abstract: A seal forming a fluid tight connection between a gas chromatography column and a sample inlet assembly is disclosed. The seal is formed by a metal injection molding process. The seal has a first surface adapted for sealing with the sample inlet assembly and a second surface adapted for sealing with the column. The seal has an aperture extending between the first and second surfaces. A method of sealing a connection between a gas chromatography sample inlet assembly and a gas chromatography column is also disclosed. The method includes providing a seal as described above, compressing the first surface of the seal against an end of the inlet assembly, positioning the column in fluid communication with the aperture, and engaging the column with the second surface.

Abstract: A self-contained chromatography system is provided and includes a chromatography column, a carrier gas reservoir containing a carrier gas and an analyte stream processing device, wherein the carrier gas reservoir is disposed upstream from the chromatography column and wherein the analyte stream processing device is disposed downstream from the chromatography column. A method for implementing the self-contained chromatography system is also provided and includes generating a first system pressure upstream from the chromatography column and a second system pressure downstream from the chromatography column to cause the carrier gas to flow between the carrier gas reservoir and the analyte stream processing device. The method further includes combining a sample material with the carrier gas, introducing the combined sample to the chromatography column to generate the analyte stream and processing the analyte stream via the analyte stream processing device.

Abstract: The present invention relates to a three dimensional preconcentrator and inlet heater. The preconcentrator consists of a substrate with passageways, a conductive material coated to the top and the bottom of the substrate and an adsorbent coating covering the entire substrate. This substrate is suspended in a holding frame by a connecting bridge. The preconcentrator may also include a resistor and a proportional-integral-differential controller. The device may be used inline with a detector and can be retrofitted to existing devices. An array of preconcentrators may also be formed. The invention also relates to methods of use of the preconcentrator and methods of manufacture. A method of use includes contacting an analyte and a preconcentrator, allowing the analyte to adsorb to the preconcentrator and then desorbing the analyte. A method of manufacture involves applying the adsorbent coating by misted chemical deposition.

Abstract: A method is described for recovering a noble gas, such as xenon or krypton, from a first gas mixture comprising a plurality of components, one of which is the noble gas and the others are typically helium and/or nitrogen, argon, and relatively light fluorocarbons. The gas mixture is first conveyed to a gas chromatography column for separating the noble gas from the other components of the gas mixture. As the noble gas travels relatively slowly through the column, the other components are exhausted from the column before the relatively slow noble gas. Following the exhaust of these other components, a purge gas is supplied to the column to flush the noble gas therefrom. A second gas mixture comprising the noble gas and the purge gas is conveyed from the column to a membrane separator to separate the second gas mixture into a noble gas-rich gas stream and a purge gas-rich gas stream, which may be recirculated back to the column for re-use.

Abstract: Separator apparatus for removing an impurity or contaminant, such as oil or heavy metals, from a fluid, such as a liquid or a gas, comprises a body member having a fluid inlet and a fluid outlet, a fluid flow channel for the flow of fluid through the body member from the fluid inlet to the fluid outlet, a plurality of perforated or fluid pervious hollow members, such as spheres or balls, located in the fluid flow channel, wherein at least some of the hollow members contain a fluid treatment medium capable of removing the impurity or contaminant from the fluid as the fluid flows through the fluid flow channel. A fluid pervious or perforated hollow member loaded with a fluid treatment medium is also provided. A method for removing an impurity from a fluid is further provided.

Abstract: The present invention is directed to an apparatus and a method for continuously removing water vapor from a closed loop, re-circulated gas flow in an ion mobility spectrometer using a water permeable membrane, having a first side and a second side opposite the first side. The gas flow is disposed adjacent and carried past the first side to deposit water vapor that passes through the membrane to the second side. An exhaust flow is disposed adjacent and carried passed the second side of the membrane to remove the water vapor from the system. Therefore, the water removal apparatus continuously regenerates in-situ. Heaters, heat sinks and additional treatment systems including charcoal filters can also be included in the system to enhance its performance.

Abstract: A multi-purpose modular pyrolysis and thermal processing system (MPMPTPS) for pyrolyzing and/or vaporizing liquids and solids to create an evolved vapor suitable for introduction into a gas-chromatography and/or vapor detection system, thereby allowing detection, classification and/or identification characteristics of threat agents. The MPMPTPS system is capable of pyrolyzing and/or vaporizing liquid (in solution, suspension or colloidal form) and solid (in aerosol or powder form) form of biological and chemical threat agents in a manner that the evolved vapor may be introduced into Gas-Chromatography systems and/or vapor detection systems, without the use of any reagents and/or bottled gases.

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 inlet seal assembly for sealing an injection port member in a chromatography instrument , comprising an injection port member having a raised metal ring, an inlet seal member with an upper surface, a peripheral groove formed in the inlet seal member upper surface, a soft resinous plastic material ring positioned in the peripheral groove opposite the raised metal sealing ring, a reducing nut holding the inlet seal member against the injection port member, and threads connecting the reducing nut to the injection port member whereby to press the soft ring against the raised metal sealing ring to form a seal. The inlet seal assembly also may have a bottom seal between the inlet seal member and the reducing nut. A method of making and using the inlet seal assembly.

Abstract: Onium salt chemistry can be used to deposit very uniform thickness stationary phases on the wall of a gas chromatography column. In particular, the stationary phase can be bonded to non-silicon based columns, especially microfabricated metal columns. Non-silicon microfabricated columns may be manufactured and processed at a fraction of the cost of silicon-based columns. In addition, the method can be used to phase-coat conventional capillary columns or silicon-based microfabricated columns.

Abstract: An analyte pre-concentrator for gas chromatography is disclosed generally comprising a tube having a restricted outlet and packed with an adsorbent, wherein the tube serves as the liner of a chromatographic injector, as an adsorbent trap coupled to a chromatographic column, and/or as an adsorbent trap coupled to a headspace sampler. Preferably, a heating device allows the tube to be heated. In a preferred embodiment, the analyte pre-concentrator further comprises a column isolating accessory so that a chromatographic column can be temporarily isolated from substances flowing through the tube.

Abstract: This invention relates to a method for separation of isotopes, that is, to obtain isotopically pure fractions by separating natural 1 isotope mixtures in elements, where hydrogen is employed as ligand on the elements that are to be isotopically separated, and where the resulting compounds are gaseous at practical temperatures and pressures. More specific, the invention relates to a method for obtaining an isotopically pure 28SiH4 in industrial scale by separating the isotopes in a chromatographic column.

Abstract: A method of gas chromatograph mass spectrometry with a negative chemical ionization (NCI) process includes analyzing a standard substance for the NCI by deriving with a derivatization reagent a fatty acid with a multiple number of carbon atoms, measuring the standard substance for the NCI by negative chemical ionization, and obtaining a retention time for each of the number of carbon atoms. The method includes measuring, under a same condition, a standard sample of each of from one to a plurality of measurement object components by negative chemical ionization, and obtaining a respective retention time for each of the measurement object components, and obtaining a retention index for the NCI of each measurement object component using the respective retention time of the measurement object component, and the retention time of the standard substance. The index facilitates both correcting the retention time of each measurement object component, and identifying substances.

Abstract: The present invention relates to a three dimensional preconcentrator and inlet heater. The preconcentrator consists of a substrate with passageways, a conductive material coated to the top and the bottom of the substrate and an adsorbent coating covering the entire substrate. This substrate is suspended in a holding frame by a connecting bridge. The preconcentrator may also include a resistor and a proportional-integral-differential controller. The device may be used inline with a detector and can be retrofitted to existing devices. An array of preconcentrators may also be formed. The invention also relates to methods of use of the preconcentrator and methods of manufacture. A method of use includes contacting an analyte and a preconcentrator, allowing the analyte to adsorb to the preconcentrator and then desorbing the analyte. A method of manufacture involves applying the adsorbent coating by misted chemical deposition.

Abstract: Solid phase extraction articles, well-less filtration devices, and methods of manufacturing the articles and devices are disclosed. Methods of extracting analytes from samples using the articles and devices are also disclosed. The articles, devices and methods include a solid phase extraction medium (SPE medium) that incorporates thermoplastic material, e.g., in the form of thermoplastic particles enmeshed within a fibril matrix.

Abstract: Disclosed are systems and methods that include a thermal desorption unit, a chromatographic column, and an interface device between the unit and the column. The interface device controls the fluid flowing into the column, such as by providing additional carrier gas to maintain a substantially constant gas flow or velocity, by proving a controlled temperature increase, or by venting a portion of the gas received from the thermal desorption unit, thereby removing the dependence on the thermal desorption unit for such control. In some embodiments, the interface is a chromatographic injector. In certain embodiments, a transfer line from the desorption unit is coupled to the same port of the interface device as the chromatographic column. In some of these embodiments, this is accomplished by employing a special adaptor.

Abstract: A non-planar microfabricated gas chromatography column comprises a planar substrate having a plurality of through holes, a top lid and a bottom lid bonded to opposite surfaces of the planar substrate, and inlet and outlet ports for injection of a sample gas and elution of separated analytes. A plurality of such planar substrates can be aligned and stacked to provide a longer column length having a small footprint. Furthermore, two or more separate channels can enable multi-channel or multi-dimensional gas chromatography. The through holes preferably have a circular cross section and can be coated with a stationary phase material or packed with a porous packing material. Importantly, uniform stationary phase coatings can be obtained and band broadening can be minimized with the circular channels. A heating or cooling element can be disposed on at least one of the lids to enable temperature programming of the column.

Abstract: The present invention provides a chromatograph/mass spectrometer capable of producing a composite chromatogram from plural chromatogram signals without causing the baseline level to rise or the intensity of the chromatogram peak to decrease. The chromatograph/mass spectrometer includes a chromatograph unit for separating a sample into components in the order of time, a mass spectrometer unit for analyzing the components of the sample, and a signal generator for producing a signal carrying a chromatogram obtained by the analysis. It also includes a chromatogram composer for receiving signals of plural chromatograms simultaneously measured under different conditions, for choosing the largest value of the plural signals for each point in time, and for integrating the chosen values to produce a composite chromatogram.

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: 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: A gas chromatography/mass spectrometry system includes two sample introduction parts, a gas chromatography part having two columns, a column oven for housing the two columns in a parallel configuration, an interface part through which an outlet end of each of the two columns is inserted, and a mass spectrometry part. The mass spectrometry part has an ionization chamber to which the outlet ends of the columns inserted through the interface part are connected, a mass separation part, an ion detector, and a vacuum chamber for housing the ionization chamber, the mass separation part, and the detector. Because the outlet ends of the parallel columns are both connected to the ionization chamber, the carrier gas flow and line velocity are the same as though there is one column, thereby avoiding line stagnation. Since analyses can be performed selectively with a single system, results having high reliability and precision can be obtained.

Abstract: An Apparatus and method for two-stage chromatographic separation uses thermal modulation. The chromatographic column or modulation tube (1) has a loop structure such that two portions of modulation tube (1) can be thermally modulated simultaneously by at least one thermal modulation device, which device can have a cold gas source, jet tube (2), and a hot gas source, hot jet tube (5), to modulate the temperature of the portions (3, 4) of modulation tube (1).

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: 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: Process for the production of a hydrofluoroalkane, according to which hydrofluoroalkane comprising organic impurities is subjected to at least two distillations.

Abstract: The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber.