Abstract: Described are a fraction collector and a method of fraction collection for a liquid chromatography system. The method includes diverting a liquid chromatography system flow from a waste channel to a collection tube at a start of a fraction collection window and collecting the system flow dispensed from the collection tube during the fraction collection window. At the end of the window, the system flow is diverted to the waste channel and a flow of a wash solvent is provided to the collection tube to dispense liquid remaining in the collection tube at the end of the window from the collection tube. The method can increase the amount of the collected fraction and can reduce or eliminate cross-contamination of a subsequently collected fraction. The method is useful for analytical scale applications where the collected fractions may have volumes defined by a limited number of drops dispensed from the collection tube.

Abstract: Described is an apparatus for controlling a position of a sample in a liquid chromatography system. The apparatus includes a rotary drive mechanism, a stepper motor and a rotational coupling system such as a drive belt and pulley system. The rotational coupling system transfers the rotational motion of a motor shaft to a shaft of the rotary drive mechanism. Advantageously, the stepper motor is remote to the sample compartment for improved safety in the event that volatile gas accumulates within the sample compartment. The rotary drive mechanism can be configured in a small form factor and can provide highly stable rotation of an attached sample tray to accommodate the requirements of compact liquid chromatography systems. In addition, leakage from inside the sample compartment to the ambient environment is substantially reduced or eliminated, resulting in better thermal control of the sample compartment.

Abstract: Apparatus and method measure the flow rate of fluid for use in calibrating fraction collection in a chromatography system. An injector inserts a detectable substance into a flow of fluid. A first detector, disposed in a path of the flow of liquid with the substance, produces a signal in response to detecting the substance in the flow of fluid. A second detector, disposed downstream from the first detector in the path of the flow of fluid with the substance, produces a signal in response to detecting the substance in the flow of fluid. A computing system receives each signal produced by the first and second detectors upon detecting the substance in the flow of fluid, and computes a volumetric flow rate of the flow of fluid based on a time interval between the signals and a volume of the path between the first and second detectors.

Abstract: Described is an apparatus for controlling a position of a sample in a liquid chromatography system. The apparatus includes a rotary drive mechanism, a stepper motor and a rotational coupling system such as a drive belt and pulley system. The rotational coupling system transfers the rotational motion of a motor shaft to a shaft of the rotary drive mechanism. Advantageously, the stepper motor is remote to the sample compartment for improved safety in the event that volatile gas accumulates within the sample compartment. The rotary drive mechanism can be configured in a small form factor and can provide highly stable rotation of an attached sample tray to accommodate the requirements of compact liquid chromatography systems. In addition, leakage from inside the sample compartment to the ambient environment is substantially reduced or eliminated, resulting in better thermal control of the sample compartment.

Abstract: Described is a dispensing needle for a fraction collector. The dispensing needle includes a conduit having a fluid channel to conduct a chromatographic flow, an interior wall that defines the fluid channel, an exterior surface and an endface through which the chromatographic flow is dispensed. The dispensing needle also includes a coating of a hydrocarbon material or a fluorocarbon material that is bonded to the endface. The coating is also bonded to at least a portion of the exterior surface that is adjacent to the endface and at least a portion of the interior wall that is adjacent to the endface. The coating operates to reduce a droplet volume of a liquid dispensed from the endface that may remain at the tip of the dispensing needle. Consequently, the concentration variation in a collected fraction due to a missing droplet or extra droplet is reduced.

Abstract: Apparatus and method measure the flow rate of fluid for use in calibrating fraction collection in a chromatography system. An injector inserts a detectable substance into a flow of fluid. A first detector, disposed in a path of the flow of liquid with the substance, produces a signal in response to detecting the substance in the flow of fluid. A second detector, disposed downstream from the first detector in the path of the flow of fluid with the substance, produces a signal in response to detecting the substance in the flow of fluid. A computing system receives each signal produced by the first and second detectors upon detecting the substance in the flow of fluid, and computes a volumetric flow rate of the flow of fluid based on a time interval between the signals and a volume of the path between the first and second detectors.

Abstract: Described are a fraction collector and a method of fraction collection for a liquid chromatography system. The method includes diverting a liquid chromatography system flow from a waste channel to a collection tube at a start of a fraction collection window and collecting the system flow dispensed from the collection tube during the fraction collection window. At the end of the window, the system flow is diverted to the waste channel and a flow of a wash solvent is provided to the collection tube to dispense liquid remaining in the collection tube at the end of the window from the collection tube. The method can increase the amount of the collected fraction and can reduce or eliminate cross-contamination of a subsequently collected fraction. The method is useful for analytical scale applications where the collected fractions may have volumes defined by a limited number of drops dispensed from the collection tube.

Abstract: Described is a dispensing needle for a fraction collector. The dispensing needle includes a conduit having a fluid channel to conduct a chromatographic flow, an interior wall that defines the fluid channel, an exterior surface and an endface through which the chromatographic flow is dispensed. The dispensing needle also includes a coating of a hydrocarbon material or a fluorocarbon material that is bonded to the endface. The coating is also bonded to at least a portion of the exterior surface that is adjacent to the endface and at least a portion of the interior wall that is adjacent to the endface. The coating operates to reduce a droplet volume of a liquid dispensed from the endface that may remain at the tip of the dispensing needle. Consequently, the concentration variation in a collected fraction due to a missing droplet or extra droplet is reduced.

Abstract: Described is a dispensing needle for a fraction collector. The dispensing needle includes a conduit having a fluid channel to conduct a chromatographic system flow. The dispensing needle also includes a needle tip that has a fluid channel and an endface. The fluid channel of the needle tip is disposed at a dispensing end of the conduit and has a cross-sectional area that is less than a cross-sectional area of the fluid channel of the conduit. The fluid channels are in communication and enable a liquid chromatography system flow at a first velocity in the conduit to be dispensed at the endface of the needle tip at a second velocity that is greater than the first velocity. Advantageously, any droplets that may form at the endface of the needle tip are reduced in volume and therefore concentration variations for collected fractions are reduced.

Abstract: Described are techniques for use with an injection port. The injection port includes a needle support structure configured to accommodate a needle containing a sample aspirated therein. The injection port includes a needle seal having a first surface thereof in contact with a second surface of a tip of the needle. A seal is formed when the first surface contacts the second surface and a sufficient force is applied to the needle.

Abstract: Described is a compound sample needle for a liquid chromatography system. In one embodiment, the compound sample needle includes a rigid needle having a coupling end with a face and a counterbore. The compound sample needle also includes a flexible tubing having an outer surface and a coupling end disposed in the counterbore of the rigid needle. The coupling end of the flexible tubing has a face adjacent to a base of the counterbore. The coupling ends of the rigid needle and flexible tubing are secured to each other by a weld formed along a circumference of the outer surface and the face of the rigid needle. A rigid sleeve protects the welded joint. The compound sample needle is suitable for injection into the high pressure mobile phase of ultra performance liquid chromatography systems.

Abstract: Described are techniques for force sensing. A computing device is configured to have a desired force setting. A first vertical position of a needle is determined using the computer device. A control signal is sent from the computing device to a positioning device. In response to the control signal, the needle is positioned at the first vertical position. When in the first vertical position, surfaces of a tip of the needle are in contact with surfaces of an opening of a sealing member and positioning the needle causes application of a force at surfaces of the opening in contact with surfaces of the tip of the needle. In response to application of the force, a spring is compressed a distance that is proportional to the force. The force is measured using a force sensor.

Abstract: Disclosed is a chromatographic system and method which includes a passive pre-heater assembly. In the inventive system and method a fluid mixture is supplied from an injector to the pre-heater assembly and then to a chromatographic column having an active heating source. The pre-heater assembly includes a convoluted tube with first and second ends and a fluid passage extending centrally therebetween, first and second end fittings attached respectively to the first and second ends of the convoluted tube, and a thermally conductive film attached to an outer surface of the convoluted tube. The first end fitting is adapted for fluidly connecting the first end of the convoluted tube to the injector and the second end fitting is adapted for fluidly connecting the second end of the convoluted tube to the chromatographic column.

Abstract: A high pressure valve, comprising a stator having a stator sealing surface with at least one stator port and a rotor having a rotor sealing surface with at least one rotor port or channel. The rotor is movable with respect to the stator to selectively move the rotor port or channel into and/or out of alignment with the stator port thereby to open and/or close the valve. The stator port is provided by a passage with a first part that extends perpendicularly from the stator sealing surface and a second part that extends from the first part in a direction that is other than perpendicular from the stator sealing surface.

Abstract: Described are techniques for use with an injection port. The injection port includes a needle support structure configured to accommodate a needle containing a sample aspirated therein. The injection port includes a needle seal having a first surface thereof in contact with a second surface of a tip of the needle. A seal is formed when the first surface contacts the second surface and a sufficient force is applied to the needle.

Abstract: Described are techniques for force sensing. A computing device is configured to have a desired force setting. A first vertical position of a needle is determined using the computer device. A control signal is sent from the computing device to a positioning device. In response to the control signal, the needle is positioned at the first vertical position. When in the first vertical position, surfaces of a tip of the needle are in contact with surfaces of an opening of a sealing member and positioning the needle causes application of a force at surfaces of the opening in contact with surfaces of the tip of the needle. In response to application of the force, a spring is compressed a distance that is proportional to the force. The force is measured using a force sensor.

Abstract: Described is a compound sample needle for a liquid chromatography system. In one embodiment, the compound sample needle includes a rigid needle having a coupling end with a face and a counterbore. The compound sample needle also includes a flexible tubing having an outer surface and a coupling end disposed in the counterbore of the rigid needle. The coupling end of the flexible tubing has a face adjacent to a base of the counterbore. The coupling ends of the rigid needle and flexible tubing are secured to each other by a weld formed along a circumference of the outer surface and the face of the rigid needle. A rigid sleeve protects the welded joint. The compound sample needle is suitable for injection into the high pressure mobile phase of ultra performance liquid chromatography systems.

Abstract: Embodiments of the present invention feature a method and device for controlling the flow of fluid. One embodiment of the device for controlling the flow of fluid comprises a rotor, stator and compression means. The rotor has a rotor fluid communication means and at least one rotor load bearing surface. The rotor load bearing surface sealably engages a stationary load bearing surface. The rotor is capable of assuming a first position and a second position by rotation. The stator has a stationary load bearing surface having stator fluid communication means. The stationary load bearing surface sealably engages the rotor load bearing surface and permits rotation of the rotor with respect to the stator. At least one of the rotor bearing surface and said stator load bearing surface has a diamond-like carbon-silica coating.

Abstract: Disclosed is a chromatographic system and method which includes a passive pre-heater assembly. In the inventive system and method a fluid mixture is supplied from an injector to the pre-heater assembly and then to a chromatographic column having an active heating source. The pre-heater assembly includes a convoluted tube with first and second ends and a fluid passage extending centrally therebetween, first and second end fittings attached respectively to the first and second ends of the convoluted tube, and a thermally conductive film attached to an outer surface of the convoluted tube. The first end fitting is adapted for fluidly connecting the first end of the convoluted tube to the injector and the second end fitting is adapted for fluidly connecting the second end of the convoluted tube to the chromatographic column.

Abstract: Embodiments of the present invention feature a method and device for controlling the flow of fluid. One embodiment of the device for controlling the flow of fluid comprises a rotor, stator and compression means. The rotor has a rotor fluid communication means and at least one rotor load bearing, surface. The rotor load bearing surface sealably engages a stationary load bearing surface. The rotor is capable of assuming a first position and a second position by rotation. The stator has a stationary load bearing surface having stator fluid communication means. The stationary load bearing surface sealably engages the rotor load bearing surface and permits rotation of the rotor with respect to the stator. At least one of the rotor bearing surface and said stator load bearing surface has a diamond-like carbon-silica coating.