Abstract: Thermally modulated variable restrictors used in chromatography systems enable independent control of system pressure and linear velocity of a compressible mobile phase passing through a chromatography column. A method for configuring a chromatography system with independent control of system pressure and mass flow rate of a compressible mobile phase includes determining a type of chromatography separation column to be used in the chromatography system, matching a thermally modulated variable restrictor to the type of chromatography separation column for use together during operation of the chromatography system, and bundling the chromatography column with its matching thermally modulated variable restrictor for distribution as a single package.

Abstract: A method for injecting a diluted sample in a chromatography system includes merging a flow of a sample and a flow of a diluent to form a flow of a diluted sample. A dilution ratio of the diluted sample equals a sum of the volumetric flow rates of the sample and the diluent divided by the volumetric flow rate of the sample. The diluted sample is stored in a holding element before injection into a chromatographic system flow. Sample dilution occurs under low pressure relative to the chromatographic flow thereby allowing lower pressure sample and diluent syringes to be used. Other benefits include reduced compressibility and a reduction in leaks due to the lower pressure operation. The method avoids problems associated with manual techniques which can introduce errors due, for example, to loss of sample, sample precipitation and adsorption of sample to vials.

Abstract: A method for detecting an analyte in a chromatography system includes performing a separation using a mobile phase that includes an organic component. The separation is performed with a primary separation module such as a chromatographic column. A first effluent, from the primary separation module, is modulated so that a fluidic plug containing an amount of the organic component and an analyte is provided to a secondary separation module where a secondary separation is performed. A second effluent, from the secondary separation module, includes temporally-resolved organic component and analyte peaks due to selective retention of the analyte. The second effluent is provided to a flame-based detector which is disabled when the organic modifier peak is received and enabled at least during the time when the analyte peak is received. Thus the analyte can be detected without interference from any response of the detector to the organic component peak.

Abstract: Thermally modulated variable restrictors used in chromatography systems enable independent control of system pressure and linear velocity of a compressible mobile phase passing through a chromatography column. A method for configuring a chromatography system with independent control of system pressure and mass flow rate of a compressible mobile phase includes determining a type of chromatography separation column to be used in the chromatography system, matching a thermally modulated variable restrictor to the type of chromatography separation column for use together during operation of the chromatography system, and bundling the chromatography column with its matching thermally modulated variable restrictor for distribution as a single package.

Abstract: A method for injecting a diluted sample in a chromatography system includes merging a flow of a sample and a flow of a diluent to form a flow of a diluted sample. A dilution ratio of the diluted sample equals a sum of the volumetric flow rates of the sample and the diluent divided by the volumetric flow rate of the sample. The diluted sample is stored in a holding element before injection into a chromatographic system flow. Sample dilution occurs under low pressure relative to the chromatographic flow thereby allowing lower pressure sample and diluent syringes to be used. Other benefits include reduced compressibility and a reduction in leaks due to the lower pressure operation. The method avoids problems associated with manual techniques which can introduce errors due, for example, to loss of sample, sample precipitation and adsorption of sample to vials.

Abstract: A method for detecting an analyte in a chromatography system includes performing a separation using a mobile phase that includes an organic component. The separation is performed with a primary separation module such as a chromatographic column. A first effluent, from the primary separation module, is modulated so that a fluidic plug containing an amount of the organic component and an analyte is provided to a secondary separation module where a secondary separation is performed. A second effluent, from the secondary separation module, includes temporally-resolved organic component and analyte peaks due to selective retention of the analyte. The second effluent is provided to a flame-based detector which is disabled when the organic modifier peak is received and enabled at least during the time when the analyte peak is received. Thus the analyte can be detected without interference from any response of the detector to the organic component peak.

Abstract: A microfluidic device, for use in separation systems, includes a substrate having a fluidic channel. One or more heaters made of a thick film material are integrated with the substrate and in thermal communication with the fluidic channel of the substrate. The one or more heaters produce a thermal gradient within the fluidic channel in response to a current flowing through the one or more heaters. A plurality of electrically conductive taps can be in electrically conductive contact with the one or more heaters. The plurality of electrically conductive taps provides an electrically conductive path to the one or more heaters by which an electrical supply can produce the current flowing through the one or more heaters. Alternatively, the thick film material can be ferromagnetic, and the electrical supply can use induction to cause the current to flow through the one or more heaters.

Abstract: Provided are devices and methods for sample collection and processing. A tubular body has a chamber closed at a first end by a thin penetrable barrier and open at a second end opposite the first end. The tubular body further includes a partition that divides the chamber into two adjacent compartments, wherein a first compartment of the two adjacent compartments has the partition facing opposite the open end of the chamber and a second compartment of the two adjacent compartments has the partition facing opposite the closed end of the chamber. The partition has one or more holes to allow passage of fluid from the first compartment into the second compartment. A tracking identification may be permanently affixed to the first end of the tubular body.

Abstract: The present disclosure relates to a microfluidic flame ionization detector for use in small scale separations, such as, for example, microfluidic gas chromatography and microfluidic carbon dioxide based fluid chromatography. In some arrangements, the microfluidic counter-current flame ionization detector employs a non-parallel arrangement for the introduction of combustion gases into the combustion chamber. In other arrangements, the detector housing is configured to incorporate at least one of the detector electrodes within the housing using electrically isolating fittings.

Abstract: A microfluidic device, for use in separation systems, includes a substrate having a fluidic channel. One or more heaters made of a thick film material are integrated with the substrate and in thermal communication with the fluidic channel of the substrate. The one or more heaters produce a thermal gradient within the fluidic channel in response to a current flowing through the one or more heaters. A plurality of electrically conductive taps can be in electrically conductive contact with the one or more heaters. The plurality of electrically conductive taps provides an electrically conductive path to the one or more heaters by which an electrical supply can produce the current flowing through the one or more heaters. Alternatively, the thick film material can be ferromagnetic, and the electrical supply can use induction to cause the current to flow through the one or more heaters.

Abstract: Thermally modulated variable restrictors used in chromatography systems enable independent control of system pressure and linear velocity of a compressible mobile phase passing through a chromatography column. A method for configuring a chromatography system with independent control of system pressure and mass flow rate of a compressible mobile phase includes determining a type of chromatography separation column to be used in the chromatography system, matching a thermally modulated variable restrictor to the type of chromatography separation column for use together during operation of the chromatography system, and bundling the chromatography column with its matching thermally modulated variable restrictor for distribution as a single package.

Abstract: Provided are devices and methods for sample collection and processing. A tubular body has a chamber closed at a first end by a thin penetrable barrier and open at a second end opposite the first end. The tubular body further includes a partition that divides the chamber into two adjacent compartments, wherein a first compartment of the two adjacent compartments has the partition facing opposite the open end of the chamber and a second compartment of the two adjacent compartments has the partition facing opposite the closed end of the chamber. The partition has one or more holes to allow passage of fluid from the first compartment into the second compartment. A tracking identification may be permanently affixed to the first end of the tubular body.

Abstract: The present disclosure relates to a microfluidic flame ionization detector for use in small scale separations, such as, for example, microfluidic gas chromatography and microfluidic carbon dioxide based fluid chromatography. In some arrangements, the microfluidic counter-current flame ionization detector employs a non-parallel arrangement for the introduction of combustion gases into the combustion chamber. In other arrangements, the detector housing is configured to incorporate at least one of the detector electrodes within the housing using electrically isolating fittings.

Abstract: An injection device (10) includes a carrier inlet (40), a sample inlet (46), waste outlet (44) and a chamber outlet (64) attached to separation column (66). Valves (52, 54, 56) are used to control flow such that sample flows into chamber (22) and is carried into the chamber outlet (42).

Abstract: A chemical processing apparatus includes a separation column, a pump unit configured to support nano-flow processing, at least one fluid transport tube for transporting the fluid between the pump unit and the separation column, and a connector disposed adjacent to an inlet or outlet end of the at least one transport tube. The fluid transport tube and/or the separation column includes an outer tube of a metallic material, a fused-silica capillary disposed in the outer tube, and an intermediate tube including a polymeric material disposed between and bonded to both the outer tube and the capillary.

Abstract: The present invention is a capillary interconnection fitting and method of clamping a capillary in the fitting that separates a forward ferrule that holds the capillary from a secondary clamping device. The fitting comprises a sealing ferrule, a compression screw and a clamping device. The ferrule is fitted in a compression screw that mates to a fluidic component. The clamping device is decoupled from the ferrule and coupled to the compression screw.

Abstract: Methods and devices for the management of cryogenic agents within analytical systems using freeze thaw valving having an expansion chamber that limits the flow of the cryogenic agent. The expansion chamber is fitted with an expansion nozzle through which a cryogen flows and a porous frit that allows the cryogen to be exhausted. The porous frit initially allows a rapid flow of cryogen into the expansion chamber. This rapid flow lowers the temperature of the expansion chamber causing fluid contents within a freeze thaw segment to freeze. As the cryogen expands into the expansion chamber and turns into a solid, the porous frit is occluded causing the rapid flow to be restricted. The restriction of the cryogen flow by the occlusion of the porous frit allows the freeze thaw valve to use significantly less cryogen. Sublimation of the cryogen trapped within the porous frit provides sufficient cooling to maintain the valve in its closed position.

Abstract: A freeze-thaw valve and a method of micro-machining the freeze-thaw valve is provided and includes a valve housing, wherein the valve housing defines a housing cavity and includes a housing inlet, a housing vent, a capillary tubing inlet and a capillary tubing outlet. A valve body is provided, at least a portion of which is lithographically constructed, wherein the valve body includes a refrigerant inlet, a refrigerant outlet and an expansion chamber. The expansion chamber is disposed to communicate the refrigerant inlet with the refrigerant outlet and includes a restriction region having a flow restriction. Additionally, the valve body is disposed within the housing cavity to form an insulating channel between the valve housing and the valve body.

Abstract: A method and system for measuring the flow rate of a liquid or gas within a flow channel utilizing a centrally located excitation source and a plurality of sensor means. Said excitation means is comprised of a heating element coupled with an alternating current generator. Of the plurality of sensor means, at least one of said sensors is located in a position upstream of the excitation source location, and additionally a second of said plurality of sensors is located in a position downstream of the excitation source. Instantaneous fluid flow rate is calculated utilizing a high gain differential amplifier electrically coupled to said sensors, wherein the convectively induced inductive gradient of the flowing fluid is compared to the symmetrical zero flow induction gradient. Following such a comparison, a voltage signal proportional to the flow of fluid within the channel is derived.

Abstract: A method and apparatus for monitoring and controlling the nano-scale flow rate of fluid in the operating flow path of a HPLC system. A first flow sensor is disposed in a first flow path between a first flow-divider and a fluidic tee. A second flow sensor is disposed in a second flow path between a second flow-divider and the fluidic tee. A first recycle flow restrictor is disposed in the first recycle flow path in fluid communication with the first flow-divider. A second recycle flow restrictor is disposed in the second The permeability of each recycle flow restrictor can be selected to produce a desired flow rate with each respective flow path. The output signals of the first and second flow sensors to control output of a pump within each flow path.