Abstract: Apparatus and methods of calibrating a microfluidic flow sensor, in which the flow of a fluid through a flow sensor is stopped and a first value is read from the flow sensor, then the fluid is pumped through the flow sensor sequentially at first and second selected rates, and readings from the flow sensor of the flow rate are taken for each of the rates. The readings are used in a polynomial equation to determine the actual flow rate, which is used to calibrate the sensor. The flow sensor can be connected to a computer programmed to perform the calibration method, determine the actual flow rate of the sensor, and make appropriate adjustments to the flow rate of a pump.

Abstract: A device and methods are provided, the device comprising a conductive union disposed in a conductive holder, a first fitting capable of coupling with the holder and fluidly communicating with the conductive union, and a spray tip disposed in the fitting and communicating with the conductive union along an axis. The device also comprises a ferrule and fitting capable of coupling with a second holder and communicating with a second conductive union, a tube disposed in the ferrule and fluidly communicating with the first conductive union and the spray tip along the axis. The assembly also includes an insulating member removably secured to the first and second conductive unions to electrically insulate them when they are electrically connected to first and second voltage levels, respectively.

Abstract: Apparatus and methods of calibrating a microfluidic flow sensor, in which the flow of a fluid through a flow sensor is stopped and a first value is read from the flow sensor, then the fluid is pumped through the flow sensor sequentially at first and second selected rates, and readings from the flow sensor of the flow rate are taken for each of the rates. The readings are used in a polynomial equation to determine the actual flow rate, which is used to calibrate the sensor. The flow sensor can be connected to a computer programmed to perform the calibration method, determine the actual flow rate of the sensor, and make appropriate adjustments to the flow rate of a pump.

Abstract: Apparatus and methods for isolating a component of a microfluidic analytical system are provided. An isolation manifold including a housing is used to isolate a sensitive component of a microfluidic analytical system from environmental noise and interference, such as mechanical vibrations and the like. The housing of the manifold includes an interior portion and a recess adapted to receive at least a portion the component to be isolated, such as a flow sensor. The housing has openings which allow for fluid communication through the housing to tubing used to connect the component to the analytical system. A potting agent can be used to help secure the component in place within the housing and to help minimize the potential for damage to the component.

Abstract: Improved valve and methods for analytical techniques and systems. The valve includes a main housing, together with a rotor and stator. The stator has openings therethrough which allow for fluid communication between tubing when connected to the valve, and one surface of the rotor. Ferrules can be used with a clamping assembly to tightly connect the tubing to the valve in a way which separates the clamp assemblies (for ease of connection and disassembly), yet still provides close proximity between the fluid connections. In one embodiment, a series of two or more discrete elements, which can be selectively moved relative to one another, are located within the valve in a “stacked” configuration. Each of the discrete elements includes at least one feature useful for performing chemical analysis, such as sample loops, columns, detectors, mixers and the like, all of which are useful in chromatography.

Abstract: A multi-port valve useful in chromatography or other analytical chemistry processes utilizes a ferrule and clamp assembly to connect a number of tubes or capillaries to a common port in the valve. The use of the clamping assembly, as opposed to conventional connectors such as nuts and/or bolts, permits the capillary ends to be positioned in extremely close proximity to the valve rotor and to each other, thus minimizing the volume between two capillaries when they are in brought into fluid communication with each other. At the same time, the clamps allow for easier connection and disconnection of the tubes or capillaries from the valve body. An operator can twist a screw to tighten the clamp and create a sealed connection without the need for special tools.

Abstract: A multilayered tube is provided comprising an inner layer of a tube comprising a first polymer, and a second layer of a tube comprising a second polymer. A catheter is provided comprising a multilayered tube comprising an inner layer of a tube comprising a first polymer, and a second layer of a tube comprising a second polymer. A method is provided for using a catheter for medical diagnostic or analysis, wherein the catheter comprises a multilayered tube comprising an inner layer of a tube comprising a first polymer, and a second layer of a tube comprising a second polymer. A liquid chromatography system is provided comprising tubing which comprises a multilayered tube comprising an inner layer of a tube comprising a first polymer, and a second layer of a tube comprising a second polymer.

Abstract: A multilayered tube is provided comprising an inner layer of a tube comprising a first polymer, a second layer of a tube comprising a braided layer comprising a metal or a second polymer, and a third layer of a tube comprising a polymer, which can be either the first, second, or still another third polymer. The braided tube layer provides mechanical strength and rigidity to the multilayered tube without adversely affecting the desired chemical or other properties of the inner and outer layers of the tube. A catheter is provided comprising such a multilayered tube. A method is provided for using a catheter for medical diagnostic or analysis, wherein the catheter comprises such a multilayered tube. A liquid chromatography system is provided comprising tubing which comprises such a multilayered tube.

Abstract: A multi-port injection/selection valve utilizes a ferrule cluster to connect tubes or capillaries to a common port in the valve. The use of micro ferrule clusters, as opposed to conventional connectors such as nuts and/or bolts, permits the capillary ends to be positioned in extremely close proximity to the valve rotor and to each other, thus minimizing the volume between two capillaries when they are in brought into fluid communication with each other.

Abstract: A multi-port injection/selection valve utilizes a ferrule cluster to connect tubes or capillaries to a common port in the valve. The use of micro ferrule clusters, as opposed to conventional connectors such as nuts and/or bolts, permits the capillary ends to be positioned in extremely close proximity to the valve rotor and to each other, thus minimizing the volume between two capillaries when they are in brought into fluid communication with each other.

Abstract: A biocompatible column for use in high pressure liquid chromatography applications includes a biocompatible, polymeric inner tube which is located within a metallic outer tube. The polymeric inner tube has end fittings and the inner polymeric tube and such end fittings and comprise a unitary piece. Alternatively, the outside ends of the outer tube may be threaded so that appropriate polymeric end fittings can be removably attached to each end of the column. A liquid chromatography system in which the column of the present invention is used is also shown and described.

Abstract: A method for making a biocompatible filter whereby a biocompatible powder is sintered to form a disk-shaped filter. The biocompatible powder is first sized to obtain a preselected average particle size. Next, the powder is introduced to a die in which the powder is pressed to a predetermined force to form "cakes." The pressed powder "cakes" are then placed into an oven or furnace, which is heated to a preselected temperature. The powder cakes are held at the elevated temperature to sinter the particles in the powder together. After a preselected amount of time, the now-sintered powder cakes are removed and allowed to cool. This method produces biocompatible filters useful in liquid chromatography and other applications.

Abstract: An improved liquid filtering assembly used in applications such as filtering solvents for use in a liquid chromatography system. The filter assembly uses a filter cup having a large surface area which can be quickly removed and changed. The filter assembly also allows for the liquid to be drawn close to the bottom of the liquid reservoir. The filter assembly includes a coupling nut into which the tubing is secured on one side and an expansion member is secured on the other side. A seal ring is located around a portion of the expansion member. The expansion member urges the seal ring against the interior surface of the filter cup to secure the filter cup to the filter assembly. When the filter cup becomes clogged, the expansion member can be loosened to allow an operator to remove the clogged filter cup, replace it with a new filter cup, and then tighten the expansion member. Thus, the filter assembly can be reused simply by replacing the filter cup.

Abstract: A biocompatible column for use in liquid chromatography applications includes a biocompatible, polymeric inner tube which is located within a metallic outer tube. The column has biocompatible end fittings which extend beyond the ends of the outer tube. The ends of the outer tube are tapered to extend radially inward towards the longitudinal axis of the column to secure the end fittings and the inner tube in place relative to the outer tube. Alternatively, one or more biocompatible frits are included in seats in the end fittings. A passageway through the inner tube is packed with any one of a number of various packing materials. The present invention may comprise either a guard column or an analytical or preparative column. A liquid chromatography system in which the column of the present invention is used is also described.

Abstract: An assembly allowing the quick and easy connection or replacement of a column in a LC system. The assembly includes a cooperating male twist lock member and a female twist lock member. When rotated relative to one another, the male member and female member are removably attached. When attached, the assembly provides a leak-free seal at one end of a guard column, with the other end of the guard column attached to a LC system through tubing which is secured to a holder in which the guard column is positioned. In the preferred embodiment of the invention, the assembly is biocompatible and presents only chemically inert surfaces to the flow of the mobile phase and sample.

Abstract: A multiport selection valve which is biocompatible and can be used at pressures of up to 2000 psi is described. A housing made of a polymer such as polyetheretherketone has a plurality of selection ports and a common port. Located within the housing and the end at which the ports are located is a rotor seal. Located within and adjacent to the rotor seal is a rotor tip. The rotor tip has a passageway therethrough to allow fluid communication between the desired selection port and the common port. In the preferred embodiment of the invention, the housing rotor seal and the rotor tip are made of synthetic polymers which are biocompatible. The valve also includes a rotor to which a knob is attached, thus allowing an operator to select a particular selection port. In an alternative embodiment, the valve of the present invention can be attached to a bulkhead and an actuator, thereby allowing automatic operations in accordance with programmed instructions.

Abstract: An improved liquid filtering assembly used in applications such as filtering solvents for use in a liquid chromatography system. The filter assembly uses a filter cup having a large surface area which can be quickly removed and changed. The filter assembly also allows for the liquid to be drawn close to the bottom of the liquid reservoir. The filter assembly includes a coupling nut into which the tubing is secured on one side and an expansion member is secured on the other side. A seal ring is located around a portion of the expansion member. The expansion member urges the seal ring against the interior surface of the filter cup to secure the filter cup to the filter assembly. When the filter cup becomes clogged, the expansion member can be loosened to allow an operator to remove the clogged filter cup, replace it with a new filter cup, and then tighten the expansion member. Thus, the filter assembly can be reused simply by replacing the filter cup.