Abstract: An apparatus for measuring light absorbance in a liquid sample which includes a light source for directing light into a sample cell, a cylindrical sample cell, a light detector for measuring intensity of light emitted from the cell and focussing means for forming a tapered light beam to pass through the sample cell. The tapered light beam can be either a diverging beam or a coverging beam through the cell. When the light beam is a diverging beam, a masking means is positioned downstream of the cell to assure that any light striking the cell wall is not directed to the light detector.

Abstract: A gel electrophoresis cassette is provided having two plates and two spacers between the plates. The spacers are positioned slightly inward of the plate edges to form small edge spaces. A soft adhesive is positioned within the small edge spaces and, subsequent to electrophoresis, the adhesive can be easily removed from the small spaces. The plates and separators then can be separated manually.

Abstract: A filter punch construction is provided for use in conjunction with a multiwell filtration device wherein each well includes a filtration membrane. The punch has a leading surface to which is secured an elongated piercing member having a sharp point and a periphery comprising holding or cutting edges and a following surface which has a guide member. The piercing member and cutting edges pierce the filtration membrane in each well and push the entire filter and retentate thereon into a receptacle vial.

Abstract: A sealing means is provided that may be used, among other things, for sample injection apparatus used in liquid chromatography. The seal includes a jacket having a central bore through which a hypodermic needle containing a sample is inserted. The jacket includes a U-shaped cross section having an inner axial surface and an outer axial surface. Metal cylindrical bands which function as springs are positioned tightly against the inner and outer axial surfaces respectively. Each band has a slot extending through its thickness and along its entire axial length.

Abstract: A tangential flow filtration apparatus which utilizes a single manifold formed of manifold segment or manifold segments to introduce liquid to be filtered into the apparatus and to remove a filtrate stream and a retentate stream from the apparatus is provided. A plurality of filtration modules are stacked between the manifold and a plate. Holes and sealing means are provided within the filtration modules to effect flow of the filtrate, retentate and incoming liquid through the stack and manifold while preventing admixture of the filtrate with the retentate or the incoming liquid. All manifold segments with the exception the most downstream manifold segment or most upstream manifold segment from the point of introducing incoming liquid must have a filtrate to exit from both ends of the manifold segment. The most downstream or the most upstream manifold segment also can have filtrate exits from both of its ends.

Abstract: A test plate apparatus is provided having at least one set of wells comprising two essentially parallel rows of wells and a central area between the wells. Each well has a first volume for housing means for effecting a fluid interaction process such as for cell growth and a second volume which permits addition or removal of liquid from the wells without disturbing the fluid interaction process.

Abstract: The surface of a hydrophobic porous substrate is modified with an interpolymeric network of a hydrophilic crosslinked polymer and a crosslinked-polyamine epichlorohydrin resin having fixed positive charges. The hydrophobic substrate is contacted with a reaction system comprising a solution of (a) monomer precursor to the hydrophilic polymer, a nonionic or cationic polymerization initiator and a crosslinking agent and (b) a precursor to the crosslinked positively charged resin. The monomer is polymerized and cross-linked by free radical polymerization followed by heating the contacted substrate to form the charged resin.

Abstract: A spiral wound filtration cartridge construction is provided which includes a cartridge positioned within a solid outer cylinder which, in turn is positioned within a solid housing. Fluid flow within the space between the outer cylinder and housing is controlled by an end plate construction. The rigid solid end plate construction includes outer peripheral holes, the sizes and number of which are set to determine by-pass flow.

Abstract: A proportioning process and apparatus is provided for forming a liquid composition by admixture of a plurality of liquid components. The apparatus includes a main chamber, a subchamber positioned within the main chamber and conduits for introducing the liquid components sequentially into the subchamber which then overflow into the main chamber. The main chamber and subchamber are provided with outlets so that the liquid therein can be admixed to form the liquid composition. A pressure sensor in the subchamber is provided to measure the head pressure of each component in the subchamber and the main chamber which, because the dimensions of the subchamber and main chamber are known, can be used to measure the volumes of the liquid components to be admixed. A level sensor is provided at the top of the main chamber to be used as a calibration point and for overflow detection.

Abstract: A sample is injected into a capillary tube of a capillary electrophoresis apparatus. A sample solute on a porous layer is positioned in contact with an entrance end of the capillary tube and electrodes are positioned at the entrance end and exit end of the tube. The separated sample is collected at the exit end of the tube.

Abstract: A fluid delivery system is provided to deliver precise volumes of a plurality of fluids in sequence to a treatment reservoir. Fluid channels are formed in a plate structure to provide a means for delivering fluids from a plurality of fluid reservoirs to one or a plurality of treatment reservoirs. Each fluid is delivered by a system comprising a check valve in fluid communication with a fluid reservoir, a positive displacement pump in fluid communication with the check valve and an injector in fluid communication with the positive displacement pump. A partition valve is provided to direct fluid to the desired treatment reservoirs.

Abstract: An electrode structure is provided for feeding a solute sample to a capillary electrophoresis separation process. The apparatus comprises a conductive plate connected to an electrical lead and an absorbent layer wet with an electrolyte solution and positioned on the plate. A membrane containing a sample is positioned on the absorbent layer in contact with an entrance end of a capillary tube forming part of the separation process. The sample is fed to the entrance part by electromigration and/or electrosmosis under the influence of an electric field induced by an electrode.

Abstract: A process is provided for removing organics and ions from liquid. Water to be purified is first exposed to ultraviolet(UV) radiation to oxidize organics in the liquid. The UV-treated water then is passed through an electrodeionization apparatus having an ion depletion compartment containing mixed anion and cation exchange resin beads and an ion concentration compartment in a given separation stage having an anode and a cathode. A second liquid is passed through the concentration compartment which is free of or filled with ion exchange resin beads. Ions under the influence of D.C. potential pass from the depletion compartments into the concentration compartments through ion permeable membranes. The electrodeionization apparatus can be operated continuously in conjunction with the UV radiation step since resin regeneration is not required.

Abstract: A sealing means is provided that may be used, among other things, for sample injection apparatus used in liquid chromatography. The seal includes a jacket having a central bore through which a hypodermic needle containing a sample is inserted. The jacket includes a U-shaped cross section having an inner axial surface and an outer axial surface. Metal cylindrical bands which function as springs are positioned tightly against the inner and outer axial surfaces respectively. Each band has a slot extending through its thickness and along its entire axial length.

Abstract: The instant invention provides a support apparatus for a filter membrane which comprises a central porous support section and a peripheral support section, said central porous support section adapted to support a central portion of a filter membrane and said peripheral support section adapted to support a peripheral portion of a filter membrane, a base support for said central support section and said peripheral support section, and means to separate said central porous support section from said peripheral support action thereby to separate said peripheral portion of said filter membrane from said peripheral support section.

Abstract: A partition valve for use in a fluid delivery system is provided to deliver precise volumes of plurality of fluids in sequence to a plurality of treatment reservoirs. The partition valve includes a diaphragm having a top surface in contact with a plurality of fluid pressure sources. The bottom surface of the diaphragm contacts a plurality of fluid inlets and outlets. The fluid pressure sources are controlled to effect fluid communication between desired fluid inlets and fluid outlets.

Abstract: A tangential flow filtration apparatus which utilizes a single manifold to introduce liquid to be filtered into the apparatus and to remove a filtrate stream and a retentate stream from the apparatus is provided. A plurality of filtration members are stacked in a vertical arrangement between the manifold and a plate. Holes and sealing means are provided within the filtration member to effect vertical flow of the filtrate, retentate and incoming liquid through the stack while preventing admixture of the filtrate with the retentate or the incoming liquid.

Abstract: A check valve for use in a fluid delivery system is provided to deliver precise volumes of a plurality of fluids in sequence to a treatment reservoir. The check valve is in fluid communication with a positive displacement pump and with fluid reservoir. The check valve includes a housing for securing check valve elements adjacent a plate having an inlet and an outlet. The check valve includes a diaphragm positioned to seal or to open fluid communication between a check valve inlet and a check valve outlet. A fluid by-pass is provided for passage of a pressurizing fluid around the check valve into the fluid reservoir.

Abstract: An injector for a fluid delivery system is provided to deliver precise volumes of a plurality of fluids in sequence to a treatment reservoir. The injector is in fluid communication with a positive displacement pump which accepts fluid from a fluid source. The injector includes a spring loaded plunger, an end of which contacts a diaphragm adapted to seal an injector inlet from an injector outlet. The end of the plunger is shaped to seat the diaphragm against the injector outlet and to position the diaphragm away from the injector inlet.

Abstract: A composite membrane and process utilizing the membrane which is capable of selectively removing particles such as viral particles from a solution such as a protein solution is provided. The membrane comprises a porous membrane substrate, a surface skin having ultrafiltration separation properties and an intermediate porous zone between the substrate and the skin which intermediate zone has an average pore size smaller than that of the substrate. The intermediate zone is free of voids which break the skin and which directly fluid communicate with the substrate. The composite is capable of a log reduction value of at least 3 (99.9% removal) of particles selectively from solution.