Abstract: Porous polymeric structures are formed from a polymeric sheet by sequential contact of the sheet with a solvent for the sheet and then a non-solvent for the sheet. All or a portion of each non-porous sheet surface is masked to prevent a portion of a surface of the sheet from contacting the solvent. The structure can be porous through all or a portion of its thickness.

Abstract: A filtration apparatus formed by ultrasonically welding a top section to a base section with a filtration membrane interposed there between. One of the top section or base section has a plurality of radially extending energy directors and the other of the top section or base section has a circumferentially extending energy director in contact with the radially extending energy directors where ultrasonic welding is effected. The groove cosiverts some of the peeling load into texisle load.

Abstract: Purified resin particles are provided in an electrodeionization step for purifying resin particles having ion depletion compartments containing the resin particles and ion concentration compartments. Purified water having a purity of at least 1 megohm-cm is introduced into the ion depletion compartments and water for accepting ionic impurities is introduced into the ion concentration compartments. The electrodeionization step for purifying resin particles is conducted under condition to dissociate water into hydrogen ions and hydroxyl ions. The purified water is produced in an initial water purification step which also can be an electrodeionization step. The water effluent from the ion depletion compartment can be recycled either to the initial water purification step or to the inlets of the ion depletion compartments in the resin particle purification process.

Abstract: An apparatus is provided for concentrating a solute sample which can be subsequently released for analysis by capillary electrophoresis. The apparatus comprises a tube containing a short length of packed particles or gel adapted to retain sample solutes which particles are retained in the tube by tube constrictions or porous plugs. The tube includes an inlet for introducing a sample into the tube and an outlet for introducing the retained sample into a capillary electrophoresis tube.

Abstract: A composite microporous membrane is provided having a microporous nonretentive substrate and a retentive microporous layer coated directly to the substrate in the absence of an intermediate support layer.

Abstract: A gel electrophoresis cassette is formed of two plates and two spacers between the plates which plates and spacers form a void volume for housing a gel. The spacers are positioned slightly inward of the edges of the plates to form a first and a second small space. A strip and an adhesive are positioned within the small space. When the strips are removed from the small spaces, the adhesive is torn and the plates can be opened manually.

Abstract: An electrically insulated needle tip is provided for forming an electrospray from a solution containing a solute sample. The insulated needle tip is positioned between an upstream electrode and a downstream counterelectrode. The solution passes through the needle, emerges from the insulated tip and is converted to an electrospray under the influence of an electric field generated between the electrode and the counterelectrode.

Abstract: A filtration member transfer apparatus is provided for transferring one or a plurality of discrete reaction or isolation zones such as filtration membranes from a sample isolation step to an analytical apparatus. The transfer apparatus includes a template, preferably which is electrically conductive, having holes or depressions of a size, shape and position corresponding to the reaction or isolation zones. An electrically conductive adhesive is exposed in the holes or depressions of the template.

Abstract: A composite porous membrane is formed from a porous polymeric substrate having its entire surface modified with a cross-linked polymer which results in a hydrophobic and oleophobic surface. The composite membrane retains substantially all of its other original properties. The cross-linked polymer is formed in situ on the polymeric substrate from a reactant system comprising an ethylenically unsaturated monomer having at least one fluoroalkyl group, a cross-linker, and, if needed, a polymerization initiator, dissolved in a nonpolar and or weakly polar solvent system. The membrane substrate saturated with the reactant system is exposed to a suitable energy source to effect polymerization and cross linking of the monomer.

Abstract: Purified ion exchange resin particles are provided in a bifunctional electrodeionization step having anion depletion compartments containing anion exchange resin particles which are purified and cation depletion compartments containing cation exchange resin particle which are purified as well as ion concentration compartments. The bifunctional electrodeionization step for purifying resin particles is conducted under conditions to disassociate water into hydrogen ions and hydroxyl ions. Purified water having a purity of at least 1 megohm-cm is introduced into the anion depletion compartment and cation depletion compartments and water for accepting ionic impurities is introduced into the ion concentration compartments. The purified water is produced in an initial purification step which also can be an electrodeionization step.

Abstract: Method and apparatus for the microbiological testing of liquids to identify and count living microorganisms contained therein includes a tubular sleeve for collecting the liquid sample to which there is attached at one end a microporous membrane filter. Each end of the sleeve has the shape of a female receptacle portion where into one end a container housing a culture medium can be nested by force for applying the medium to the underside of the filter and where into the other end a cover can be nested to provide a substantially tight sealing of the device. Preferably, the tubular sleeve is in the form of a bellows the convolutions of which can be either compressed or expanded to correspondingly alter the volume of the sleeve between minimum and maximum values.

Abstract: A photometric apparatus is provided for analyzing a sample liquid capable of fluorescing when exposed to excitation light. The sample liquid, surrounded by a sheath liquid under conditions of laminar flow to form an interface between the sample liquid and the sheath is passed through a cell conduit. An excitation light is directed axially into the sample liquid and is totally internally reflected at the interface with the sheath liquid. The sample fluoresces in response to the excitation light and fluorescent emission is observed through the sheath liquid.

Abstract: Capillary electrophoresis is effected by introducing into a capillary a buffer solution a zwitterion composition comprised of substantially equal numbers of positive and negative charges when the negative charges are desired from sulfonate or sulfate groups and the positive charges are derived from quaternary amines, quaternary phosphines or quanternary arsines. A sample is introduced into the capillary and an electric field is established through the capillary to cause the sample to migrate through the capillary.

Abstract: A plate structure including conduit and reagent delivery means for 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 the plate structure to provide a means for delivering fluids from a plurality of fluid reservoirs attached to the plate structure to one or a plurality of treatment reservoirs attached to the plate structure. Each fluid is delivered by a system comprising a check valve in fluid communication with a fluid reservoirs, a positive displacement pump in fluid communication with the check valve and an injector in fluid communication with the positive displacement pump all of which are attached to the plate structure. A partition switch attached to the plate structure is provided to direct fluid to the desired treatment reservoirs or pressure reservoirs.

Abstract: A flow cell for optically analyzing a liquid sample is coated with a fluoropolymer having a refractive index less than the refractive index of water.

Abstract: A tangential flow filtration apparatus which utilizes a single manifold formed of a stack of 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 feed liquid through the stack and manifold while preventing admixture of the filtrate with the retentate or the feed liquid. A feed manifold is positioned at an intermediate position within the stack of manifold segments. All manifold segments with the exception of the most downstream manifold segment or most upstream manifold segment from the point of introducing incoming liquid must have a filtrate 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: Assay apparatus is provided which includes a filter such as a porous membrane, a volume that can contain an absorbent and flexible means for reducing the volume in order to effect passage of liquid sample through the membrane and into the volume. The assay apparatus can be produced by a continuous manufacturing process.

Abstract: A porous membrane is formed from an interpenetrating polymer network of a hydrophobic polymer and a polymerized and crosslinked hydrophilic monomeric composition. A solution of the polymer and monomeric composition is cast, exposed to ultraviolet radiation, coagulated and dried. The resulting dried membrane is annealed in order to render its surface hydrophilic.

Abstract: Water to be purified and degassed is passed through a reverse osmosis step which a pure water stream and a high pressure waste water stream are produced. The high pressure waste water is passed through an eductor to produce a vacuum. The pure water stream is passed into a first volume of a degassifier and the vacuum is directed to a second volume of the degassifier. The first and second volume of the degassifier are separated by a hydrophobic membrane.

Abstract: A process is provided for removing ions from water which is passed through an ion depletion compartment of an electrodeionization apparatus. The electrodeionization apparatus contains an ion depletion compartment containing mixed ion exchange resin beads and an ion concentration compartment which may contain ion exchange resin beads in a given separation stage having an anode and a cathode. The anion resin beads and cation resin beads utilized each comprise beams of substantially uniform size. A second liquid is passed through the ion concentration compartment to collect ions under the influence of DC potential which pass from the depletion compartments into the concentration compartments through ion permeable membranes. The electrodeionization apparatus can be operated continuously since resin regeneration is not required.