Abstract: A microwave heating apparatus is used for heating a chromatographic column assembly containing a microwave absorbing material. The microwave heating apparatus includes an antenna transmitting a microwave signal and a resonant cavity containing the chromatographic column assembly. The chromatographic column assembly extends relative to predetermined electromagnetic field strength contours within the resonant cavity to provide a predetermined heating profile along the length of the chromatographic column assembly. For example, a single-mode chromatographic column microwave oven can be used to heat a coiled chromatography column to a desired temperature gradient along its length. Oven design embodiments utilizing coaxial transmission line structures, coaxial resonators, and cylindrical resonators are described. Oven designs are provided to achieve more suitable oven size for fixed operating frequencies. Apparatuses for impedance matching an oven to a microwave source are described.

Abstract: A method of thermally modulating a tubular member carrying a sample substance therethrough is provided. The method includes the steps of (a) directing at least one gas stream toward a tubular member in a direction substantially transverse to the tubular member, wherein the temperature of the gas stream differs from the temperature of the tubular member; and (b) varying the gas flow rate of the at least one gas stream as a function of time to thermally modulate the tubular member.

Abstract: Rapid characterization and screening of polymer samples to determine average molecular weight, molecular weight distribution and other properties is disclosed. Rapid flow characterization systems and methods, including liquid chromatography and flow-injection analysis systems and methods are preferably employed. High throughput, automated sampling systems and methods, high-temperature characterization systems and methods, and rapid, indirect calibration compositions and methods are also disclosed. In preferred high-temperature embodiments, the polymer sample is maintained at a temperature of not less than about 75° C. during sample preparation, loading into a liquid chromatography or flow-injection analysis system, injection into a mobile phase of a liquid chromatography or flow-injection analysis system, and/or elution from chromatographic column. The described methods, systems, and device have primary applications in combinatorial polymer research and in industrial process control.

Abstract: The invention concerns a method and an apparatus for the direct injection of large volumes (>3 &mgr;l) of samples into the column in a gas chromatography analysis apparatus comprising an oven, a gas chromatography column lodged in the oven, a means for the direct transfer into the column of the sample and a source of carrier gas upstream the column, as well as a detector downstream the column. According to the invention two or more of the parameters: nature of the solvent injection rate flow-rate and/or pressure of the carrier gas temperature at least of an initial length of the column during the injection are correlated and/or controlled to achieve a control of the length of the zone wetted by the sample during its introduction.

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 microwave heating apparatus is used for heating a chromatographic column assembly containing a microwave absorbing material. The microwave heating apparatus includes an antenna transmitting a microwave signal and a resonant cavity containing the chromatographic column assembly. The chromatographic column assembly extends relative to predetermined electromagnetic field strength contours within the resonant cavity to provide a predetermined heating profile along the length of the chromatographic column assembly. For example, a single-mode chromatographic column microwave oven can be used to heat a coiled chromatography column to a desired temperature gradient along its length. Oven design embodiments utilizing coaxial transmission line structures, coaxial resonators, and cylindrical resonators are described. Oven designs are provided to achieve more suitable oven size for fixed operating frequencies. Apparatuses for impedance matching an oven to a microwave source are described.

Abstract: An electrically insulated gas chromatograph assembly suitable for high temperature operation in a miniaturized, low power, low thermal mass gas chromatograph instrument is provided. The gas chromatograph (GC) assembly includes a metal capillary GC column (152) having a ceramic fiber insulating layer (156) wrapped about an outer surface thereof. Heater wire (160) is similarly wrapped with a ceramic fiber electrical insulating layer (158). Resistive temperature device (RTD) wire (154) is positioned contiguous an outer surface of insulating layer (156). The composite assembly including insulated capillary GC column (152), insulated heater wire (160), and RTD wire (154), are bound together by applying thereto a spiral wrapped ceramic fiber insulating layer (162).

Abstract: To enable the mass injection of a sample in a gas chromatography and prevent occurrence of residue or decomposition of a desired constituent during analysis. The invention calls for providing the injection port with a liner, connecting the column and the liner to a press-fit, evaporating the solvent introduced into the liner, and discharging the evaporated solvent from a discharge port formed at the upper part of the liner.

Abstract: A sample concentration device is provided in which a gaseous sample is concentrated by cooling a portion of a gas transfer line through which the sample is introduced into a detecting apparatus, such as a gas chromatograph or the like. The device is characterized by a cooling device for cooling a portion of the gas transfer line, which is housed in a constant temperature chamber, by spraying a coolant from a nozzle facing the portion of the gas transfer line, and by a gas flow device for creating a substantially dry gas flow through the nozzle to prevent the nozzle from becoming plugged with ice formed by freezing of moisture in the air inside the constant temperature chamber when the coolant spray is stopped. An outer jacket surrounding a portion of the gas transfer line which is subjected to cooling is also disclosed.

Abstract: Apparatus and method for periodic analysis of trace amounts of volatile organic compounds in a waste gas provide for feeding of a sample of a waste gas first to an organics concentrator which isolates the volatile organic compounds from the waste gas sample and prepares a concentrated sample for feed to a gas chromatograph. In normal operation, a waste gas is continuously sampled from the waste gas source to produce a continuous waste gas flow through a switching valve and out a vent. A portion of that waste gas flow is periodically diverted by the switching valve and routed to the organics concentrator. The switching valve also receives calibration samples containing known concentrations of the volatile organic compounds prepared in a gas blender. It periodically feeds the calibration samples to the organics concentrator and the gas chromatograph for calibration of the system.

Abstract: A method for determining the efficiency of a carbon filter used to absorb hydrocarbons from organic solvents. A sample of the solution, used to remove CO.sub.2 and H.sub.2 S from natural hydrocarbon gases, is taken after it has passed through the carbon filter. A solution of an internal standard and carbon disulfide is added to the sample to concentrate the hydrocarbons into the solution. A second sample taken from the solution containing the concentrated hydrocarbons and is passed through a gas chromatograph which has a fast temperature ramp to measure the peak areas of the hydrocarbons and the internal standard. The concentration of the measured hydrocarbons are determined by comparing the peak area counts against that of the internal standard.

Abstract: A microwave heating apparatus is used for heating a chromatographic column assembly containing a microwave absorbing material. The microwave heating apparatus includes an antenna transmitting a microwave signal and a resonant cavity containing the chromatographic column assembly and the antenna. The chromatographic column assembly extends relative to predetermined electromagnetic field strength contours within the resonant cavity to provide a predetermined heating profile along the length of the chromatographic column assembly. For example, a single-mode chromatographic column microwave oven can be used to heat a coiled chromatography column to a desired temperature gradient along its length. Oven design embodiments utilizing coaxial transmission line structures, coaxial resonators, and cylindrical resonators are described. To control the electromagnetic field gradient in the axial direction, the oven designs provide for varying some part of the oven geometry in the axial direction.

Abstract: A solute and a solvent with close boiling points or close polarities are separated and concentrated by vaporizing at least one of the solvent and solute, and selectively adsorbing the vaporized component in an apparatus having a vessel, and an absorbent with an opening into the vessel.

Abstract: A method for identifying analytes of interest by referencing to a retention factor database corresponding to a plurality of identified analytes that is independent of column dimensions and carrier gas type while dependent upon stationary phase type ratio and a relative temperature program. The retention factor database is generated on a reference GC system in which the column head pressure is adjusted to ensure high reproducibility of retention times by locking the column void time and/or the retention time of an identified analyte to a specific value such that accurate retention factors (k) can be calculated in accordance with the formula: ##EQU1## where VT is the void time of the column having a specified stationary phase and phase coating installed in a GC system operating in accordance to a specified temperature program (where time is expressed in units of column void time).

Abstract: A flow of a carrier gas through a column is provided. A sample is provided in the column, and a temperature of a longitudinally short portion of the column is raised to a predetermined controlled high temperature at which volatile substances are released from the sample packing and are carried by the carrier gas. The column is cooled on each side of the short portion to a low temperature at which the volatile substances condense or adsorb on the column packing. By continuously moving the heated short portion from an inlet end to an outlet end of the packing in a direction of carrier gas flow the volatile substances selected by the controlled high temperature are released. Four particularly useful and advantageous applications can be identified for the invention. Firstly, it provides an improved gas chromatograph (GC) injector. Secondly, it provides an improved thermal separator or extractor.

Abstract: An airflow director constructed for use with a separation column in a temperature-controlled air bath in a chromatographic oven cavity, wherein the airflow director includes at least a first baffle locatable with respect to the separation column and to the low pressure and high-pressure regions of the air bath, wherein the baffle is configured to direct air flow away from the high-pressure region before passing over the separation column. The temperature-controlled air thereby mixes with oven cavity air before passing over the separation column, which is thereby less subject to thermal gradients.

Abstract: The invention provides methods and systems for identifying compounds released from a semi-conductor wafer. Compounds are released from the wafer by subjecting the wafer to a rapid temperature excursion in a very low pressure chamber. The released compounds are often isolated using gas chromatography. Diffusion between the layers of a multiple layer semi-conductor structure can be minimized by directly heating a target surface of the wafer using radiant heating.

Abstract: A liquid chromatography apparatus with stationary and mobile phase temperature controls suitable for polynucleotide separations by MIPC and DMIPC processes. The apparatus includes heater means with a temperature control system; a matched ion polynucleotide chromatography separation column having an inlet end; a coil of capillary tubing having an inlet end and an outlet end. The outlet end of the capillary tubing is connected with the inlet end of the separation column. The inlet end of the capillary tubing comprising means for receiving process liquid, the tubing having a length of from 6 to 400 cm having a linear tubing length of heating means. The separation column and the coil of capillary tubing are enclosed in the heater means. The capillary tubing preferably is PEEK or titanium. The heater means can be an air batch oven. Preferably, it is a heat-conducting block having a first heat transfer surface, a separation column receptacle, and a capillary coil receptacle.

Abstract: A microwave heating apparatus is used for heating a chromatographic column assembly containing a microwave absorbing material. The microwave heating apparatus includes an antenna transmitting a microwave signal and a resonant cavity containing the chromatographic column assembly and the antenna. The chromatographic column assembly extends relative to predetermined electromagnetic field strength contours within the resonant cavity to provide a predetermined heating profile along the length of the chromatographic column assembly. For example, a single-mode chromatographic column microwave oven can be used to heat a coiled chromatography column to a desired temperature gradient along its length. Oven design embodiments utilizing coaxial transmission line structures, coaxial resonators, and cylindrical resonators are described. To control the electromagnetic field gradient in the axial direction, the oven designs provide for varying some part of the oven geometry in the axial direction.

Abstract: A device for carrying out solid phase microextraction is a tubular member having one closed end and one open end with an extracting surface within said tubular member. The extracting surface can be an extracting phase coating extending over a zone within the tubular member. The tubular member has a heater that can be used for either or both drawing fluid carrier into the tubular member or assisting in desorbing analytes into an injector of an analysis instrument. The tubular member can also be mounted in a housing with an airtight cavity and a plunger. A method of operation of the device is also provided. Previously, samples were analyzed using liquid-liquid extraction or using cartridges. Both of these methods are relatively expensive and time consuming. Both of these methods also require the use of solvents which can be difficult and expensive to dispose of.

Abstract: A chromatography column for microwave heating either incorporates microwave absorbing material into the column itself or positions the column adjacent to microwave absorbing material so that the column and the chromatography sample contained therein are heated by the microwave absorbing material via conduction or convection. For example, a microwave absorbing material (e.g., ferrite) can be fused into the inner silica layer or incorporated in an outer polymer layer of the column. Microwave absorbing material can also be incorporated into an external element (e.g., an outer tube, sleeve, or spool) positioned adjacent to the chromatography column. A layer of thermal insulation can be placed around the column to decrease the rate of heat loss. Optionally, a gap can be provided between the chromatography column and thermal insulation to further reduce heat loss during the heating cycle and to accelerate cooling at the end of the heating cycle by making it possible to ventilate the heated column.

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: A method and apparatus for separating selected materials in a gas chromatograph. The gas mixture is introduced into a separation column of the gas chromatograph and the separation column is heated inside a chamber of the gas chromatograph to a preset temperature. The preset temperature is matched to the material to be separated and that heating is accomplished by using IR radiation.

Abstract: A primary chromatographic system is operated with a standard sample at several temperatures to generate primary retention times which are fitted to a function to determine thermodynamic constants to relate the times to temperature. A target chromatographic system is operated with the standard sample to generate secondary retention times. The function is used with these times to determine and an effective column parameter for the target system. The function then is used with this parameter and the primary times to determine a pressure program. Further operation of the target system with a application sample and the pressure program effects standardized retention times. A particular searching technique is utilized to apply the function. A temperature calibration technique with a selected sample measures column temperature for the target system, and a validation is done on the target system.

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 precolumn separator provides a method of separating a solvent from a sample for use in a gas chromatograph. The precolumn has an independent carrier gas control mechanism which allows the carrier gas to be passed through the preseparation column at a rate favorable for stripping the solvent from the sample. The solvent-laden carrier gas is then purged through a purge vent which is separate from the gas chromatograph. After a period of time which effectively permits the carrier gas to be significantly removed from the sample, the flow rate of the carrier gas is reduced to the normal operating gas flow rate and the purge vent is closed. The sample is then passed through the column to the gas chromatographic column. A second purge vent can then be directed to the purge vent inlet in the gas chromatograph. Preferably, the preseparation column is a packed column which includes a separate heating element. The heating element, in turn, can be surrounded by an air cooled jacket.

Abstract: A chromatography column for microwave heating either incorporates microwave absorbing material into the column itself or positions the column adjacent to microwave absorbing material so that the column and the chromatography sample contained therein are heated by the microwave absorbing material via conduction or convection. For example, a microwave absorbing material (e.g., ferrite) can be fused into the inner silica layer or incorporated in an outer polymer layer of the column. Microwave absorbing material can also be incorporated into an external element (e.g., an outer tube, sleeve, or spool) positioned adjacent to the chromatography column. A layer of thermal insulation can be placed around the column to decrease the rate of heat loss. Optionally, a gap can be provided between the chromatography column and thermal insulation to further reduce heat loss during the heating cycle and to accelerate cooling at the end of the heating cycle by making it possible to ventilate the heated column.

Abstract: A flow of a carrier gas through a column is provided. A sample is provided in the column, and a temperature of a longitudinally short portion of the column is raised to a predetermined controlled high temperature at which volatile substances are released from the sample packing and are carried by the carrier gas. The column is cooled on each side of the short portion to a low temperature at which the volatile substances condense or adsorb on the column packing. By continuously moving the heated short portion from an inlet end to an outlet end of the packing in a direction of carrier gas flow the volatile substances selected by the controlled high temperature are released. Four particularly useful and advantageous applications can be identified for the invention. Firstly, it provides an improved gas chromatograph (GC) injector. Secondly, it provides an improved thermal separator or extractor.

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: In a gas chromatograph system having a column with a stationary phase and a carrier gas moving through the column to contact the stationary phase, the system being useful for detecting analytes in a sample, a method and apparatus for predicting the retention times for the analytes under various conditions, the method utilizing the steps of:a) detecting the analytes under a number of sets of given conditions;b) calculating values for various parameters characteristic of the system based on a mathematical model that includes a correction to compensate for the permeability of said column to said carrier gas;c) entering into the model the values for the characteristic parameters and at least one further set of conditions; andd) using the model to predict retention times for conditions other than those of step a;the apparatus composed of a data handling system including a model for predicting retention times at a variety of conditions of operation of the system, the model having a first set of inputs including ret

Abstract: A gas chromatographic method utilizes columns having either ascending or descending temperature profiles to effect separation even under column overloading conditions. A fixed ascending temperature profile column allows for good separation of components of a mixture under conditions of column overloading. A mixture to be separated is chromatographed on at least one such column prior to chromatography on a column maintained with a descending temperature profile. This latter column has surprisingly been found to greatly reduce tailing of less volatile species. The invention also includes a variable temperature descending column chromatography to provide an initial ordering of a large quantity of components prior to chomatography on the fixed ascending temperature profile column, or on the serial fixed ascending and descending temperature profile pair of columns.

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: A method of admitting and receiving a sample into a gas chromatographic column is provided in which a step increase in pressure is performed in combination with the application of a negative axial thermal gradient to provide pre-separation of solutes in the sample within the inlet region of the column. The method includes the steps of introducing a sample into the column at a first pressure and temperature, rapidly raising the temperature to invoke a negative axial thermal gradient, and then substantially instantaneously increasing the pressure. The method causes the solutes in the sample to be partially separated into narrow zones within the inlet region, resulting in eventually achieving maximum resolution.

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 precolumn separator provides a method of separating a solvent from a sample for use in a gas chromatograph. The precolumn has an independent carrier gas control mechanism which allows the carrier gas to be passed through the preseparation column at a rate favorable for stripping the solvent from the sample. The solvent-laden carrier gas is then purged through a purge vent which is separate from the gas chromatograph. After a period of time which effectively permits the carrier gas to be significantly removed from the sample, the flow rate of the carrier gas is reduced to the normal operating gas flow rate and the purge vent is closed. The sample is then passed through the column to the gas chromatographic column. A second purge vent can then be directed to the purge vent inlet in the gas chromatograph. Preferably, the preseparation column is a packed column which includes a separate heating element. The heating element, in turn, can be surrounded by an air cooled jacket.

Abstract: The present invention enables the dissipation of thermal energy from a gas chromatography chamber containing a gas chromatography sample by providing the housing in two parts so that ambient air can be bled in during a creation of thermal energy with a heater and additional ambient air can be circulated in a cooling cycle. Additionally, a heat exchanger for receiving liquid nitrogen can also be included to increase the speed in which thermal energy can be dissipated.

Abstract: A gas chromatograph has a control unit which normally carries out a pressure control so as to keep the pressure inside the vaporization chamber at a specified target level while the flow rate of a carrier gas into the vaporization chamber is kept constant. When a liquid sample is injected to cause a sudden rise in the pressure, the normal pressure control is temporarily stopped, say, for keeping the split ratio unchanged. In order to keep unchanged the retention time for components being analyzed although the pressure inside the vaporization chamber rises, the target value for the pressure control is reduced for an appropriate length of time after the temporary stopping of pressure control is discontinued.

Abstract: A microtrap sample concentrator useful for concentrating a sample of purged gas containing analytes for delivery to an analytical instrument, including: a tube containing at least one sorbent material which retains or traps analytes; where greater than 30% of all trapped analytes are directly delivered to an analytical instrument at a desorption flow rate of one to three cc/min, without splitting or cryogenic focusing the trapped analytes; where delivery of the trapped analytes to the analytical instrument is achieved by passing the trapped analytes through a passage being selectively connectable between the microtrap and the analytical instrument, the passage connected to a vent; where the temperature of the passage is not lower than ambient room temperature; and where the passage is heated to a temperature sufficient to vaporize water in the passage and to expel the vaporized water out of the vent.

Abstract: To inject a liquid sample with large volume into a GC column of a gas chromatograph, its volatile portion is evaporated by heat, in a non-selective way, in a vaporization chamber, the vapors thus generated being fed to pre-column located upstream of the GC column and maintained at a lower temperature to that of the vaporization chamber, where such compounds are separated from the solvent vapors, which are unloaded into the atmosphere while the compounds to be analyzed are sent to the GC column.

Abstract: The invention relates to a method and a device to control the physical conditions of the solvent within a pre-column, in a gas chromatography analysis apparatus. To achieve desired and controlled conditions of recondensation in the pre-column with vaporization injectors or of vaporation with "on-column" injectors, the dew-point of the solvent in the pre-column is calculated and the factors which influence this dew-point are varied and/or the temperature of the pre-column is varied, in order to set such temperatures in a desired correlation.

Abstract: A chromatography oven is described to achieve faster cool-down rates and to preferably lower the temperature difference that can be maintained between the oven temperature and ambient temperature. The oven includes a suitable housing having front and rear walls and four side walls, a fan within the housing adjacent to the rear walls, an ambient air intake vent means in the rear wall, and an exhaust vent means within a rear corner of one of the side walls adjacent to the rear wall for exhausting the tangential flow of air created by the rotating fan.

Abstract: A device and method are described for the gas chromatographic separation of a sample, aimed in particular at the analysis of large volume samples. Provision is made for the use of calculating and memorizing a plurality of reference values corresponding to the evaporation rates of solvents combined with a carrier gas for a corresponding plurality of discrete values representing the conditions of pressure, temperature, injected sample volume and sample injection rate. The effective solvent evaporation rate is then calculated in correspondence to the effective conditions in which the process is carried out to determine the volumetric fraction of the sample which is transferred through the capillary column in relation to its characteristics and geometrical dimensions.

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: To avoid deposits on the restrictor that channels extractant into a collector, a heated capillary tube pressure release restrictor, has a thermally insulated outlet end in a collecting trap substantially colder than the capillary tube. The restrictor is heated between the insulation and the capillary tube by Joulean heating. The solvent in the trap is at a pressure of 5 to 200 psi above atmospheric pressure. The thermal resistance of the insulation is selected to reduce the heat added to the extractant to a minimum and yet cause the temperature of the extractant to be in a range within which it is sufficiently hot so it does not freeze when added to the collection solvent but not so hot as to reduce partitioning of the extract and extractant before the extractant leaves the collection solvent. It has a thermal conductivity no greater than 60 BTU's per hour, per square foot, per inch for a one degree Fahrenheit difference.

Abstract: A high-performance, field-portable, thermally agile, gas chromatography (GC) system employs a low-thermal-mass oven in which intake and exhaust vent apertures are aligned with respect to the rotational axis of the stirring fan. The poppets of the vent dynamically vent to ambient the air-flow generated by the stirring fan. The geometry of the vents cooperates with the axial and radial components of the stirring fan to promote conical vortex air flow, to facilitate rapid and controllable mass-flow interchange with ambient air. The resulting cooling performance in a small GC oven promotes more rapid requilibration between runs, control at temperatures closer to ambient, and the reduction of thermal overshoot; thus enhancing the performance and productivity of a field instrument.

Abstract: Gas chromatographs are disclosed that may be constructed to be portable, light, rugged, fast, sensitive, and to use only utilities (compressed gas and electricity) that are readily available in the field. The gas chromatographs can also perform novel extractions of analytes from gaseous, liquid, or solid samples. The chromatographs can be truly portable; they can operate with approximately 100 watts of power (at peak power consumption); and they are extremely fast. The chromatographs are not limited just to portable applications, but will also find many uses within laboratories, because they require minimal laboratory bench or other space, because they can operate at high speed, and because they can operate with minimal consumption of utilities (compressed gases, air conditioning, etc.).

Abstract: A cryogenic trap apparatus for cooling is disclosed as well as heating of a capillary column in order to analyze the volatile components of any volatile or semi-volatile compound passing through the capillary column. The cryogenic trap is restricted to treatment of one inch or less in length of the capillary column in order to achieve miniaturization of the design. A cylindrically shaped main cryogenic chamber with a volume of less than 0.5 cubic inches is adapted to receive the capillary column extending axially therethrough and includes a cooling fluid inlet and a cooling fluid outlet as well as a heating apparatus for achieving rapid cooling and thereafter rapid heating of the components in the capillary column for trapping and segregating individual components thereof for chromatographic analysis.

Abstract: The present invention is directed to methods and apparatus for conducting gas chromatography more rapidly than previously disclosed. By means of the present invention the time necessary to conduct a gas chromatographic analysis can be reduced by more than 50%. The methods and apparatus employed reduce system dead volumes to prevent band broadening and mixing of the sample components as the gas sample is analyzed. The present invention also relates to the apparatus described above as applied to controlling chemical, refining, and other processes.

Abstract: A gas chromatograph system including a cold trap having two portions, a capillary tube and a porous layer open tubular (PLOT) column, for substantially simultaneously trapping lower and higher boiling point gasses. The capillary tube enables cold trapping of lower boiling point gasses while the PLOT column enables cold trapping of higher boiling point gasses. The capillary tube interconnects at one end to an analytical column and a sample gas source and interconnects at its other end to a first end of the PLOT column. The other end of the PLOT column interconnects to a carrier gas source and a vacuum source. The capillary tube and PLOT column are both positioned within a temperature controlled environment of the cold trap. During the collection mode, the temperature control device maintains a relatively low temperature to condense the sample components.

Abstract: A method for analyzing organic substances, includes the steps of subcooling a semiconductor substrate to a temperature at least lower than an ambient temperature, trapping volatile organic substances present in an atmosphere on the semiconductor substrate, heating the semiconductor substrate to thereby remove the volatile organic substances from the semiconductor substrate, and analyzing the volatile organic substances. This method is capable of selectively trapping to analyze only organic substances which might be adsorbed to a semiconductor device and thereby deleteriously affect the performances of the semiconductor device.