Abstract: There is described a fluid dispensing system which includes a pipette assembly adapted for use with disposable pipette tips. To ensure a precise location of a disposable pipette tip on the distal end of the stem of the pipette assembly which holds the pipette tip, a proximal chamber of the pipette tip envelops the distal end of the stem and includes a ledge which encircles an annular region of the stem to form an abutment for the stem and establish a precise distance between the distal end of the stem and the pipette tip orifice. In a preferred embodiment the fluid dispensing system is incorporated in an automated analytical instrument.

Abstract: An automated assay system includes a temperature controlled chamber with a conveyor therein. The conveyor carries berths past a port in a sidewall of the chamber to permit insertion and extraction of assay cartridges via the port into respective ones of the berths. An injector disposed outside the chamber and at the port includes a loader arm for advancing cartridges along a path through the port to accomplish insertion and extraction of a cartridge. A track is provided in the injector for guiding the assay module. A portion of the track connects by a swing arm to a pivot allowing the track portion to be swung away from the path for ejection of a cartridge. A door which provides for opening and closing of the port is connected to the swing arm to move concurrently with the swinging of the track portion. This allows for automatic closure of the port subsequent to an insertion or an extraction of a cartridge, and automatic opening of the port prior to insertion or extraction of the cartridge.

Abstract: An assay cartridge suitable for use with automated analytical instruments which include a conveyor such as a carousel. The cartridge is configured with ledges extending cutwardly from sides thereof, preferably at the bottom of the cartridge. The conveyor incudes berths for receiving the cartridges, each berth being formed as a depressed region within a top surface of the conveyor and bounded by a floor at the bottom of the berth and opposed sidewalls and an end wall extending upwardly from the floor. The sidewalls are preferably parallel to each other. An open end of the berth, opposite the end wall serves as a port through which the cartridge is inserted and extracted from the berth. Each of the sidewalls of the berth is provided with a shoulder which extends inwardly towards a center line of the berth, and upon insertion of the cartridge, extends over the ledges of the cartridge to serve as a guide. The guide includes grooves formed between the shoulders and the floor.

Abstract: A method for determining the amount of an analyte in a sample fluid utilizes a multilayer assay element which comprises at least one reagent layer and a light-blocking layer. The assay method includes the steps of optically reading a signal producing species, e.g. a fluorescent label, a first time before the sample fluid is applied to the assay element and a second time, at the same wavelength and in the same location within the assay element, after the sample fluid has been applied to the assay element and the sample analyte has interacted with the reagent(s) present in the assay element. The ratio of the two signals is taken and compared with that for known amounts of the analyte to determine the amount of analyte in the sample fluid.

Abstract: There is described an assay element suitable for use in an automated analytical test instrument for assaying a fluid sample. The element includes a thin porous member possessing a high degree of capillarity such as a fibrous mesh pad supported within a guide defined by surfaces contiguous the porous member. The dimensions of the porous member and its degree of capillarity are such as to provide for capillary transport of fluid through the member. A fluid dispenser and a fluid collecting chamber are disposed contiguous to opposed ends of the porous member. The fluid dispenser is formed as a well with a port at the bottom of the well, the port being contiguous the porous member and having a ridge extending along a perimeter of the port. The ridge protrudes into the porous member a distance sufficient for entraining fluid present in the well to propagate within the member rather than along an interface between a surface of the member and guide surfaces which hold it in place.

Abstract: There is described an analytical isntrument for the analysis of fluids such as biological fluids. The instrument includes a fluid dispensing system having a pipette for dispensing fluid test samples and test reagents to assay cartridges. An optical detection system provides a light beam which intercepts a downward travel path of the pipette prior to its reaching the dispense position. Measurement of the intensity of the light beam in conjunction with the position of the pipette enables a controller to indicate the presence or absence of a pipette tip. In addition, interception of the light beam by the pipette initiates a final approach sequence for the pipette to the dispense position above an assay cartridge by a predetermined increment of travel.

Abstract: A method of calibrating pipette position in an automated assay instrument employing a conveyor for holding assay cartridges and a transport for transporting a pipette between various locations is accomplished by alignment of a pipette stem with targets located at various locations within the system. Two targets are located on a tray having a plurality of reservoirs for holding liquid, and one target is located on a dummy cartridge carried by the conveyor. An indicator having a spring-loaded tab is used in conjunction with a pipette stem modified by inclusion of a circumferential slot for receiving the spring loaded tab. The stem is inserted into the indicator and locked therein, with limited sliding being provided by movement of the tab within confines of the slot. Alignment marks are provided on both the stem and the indicator to permit visual alignment of the stem relative to a target upon abutment of the indicator with the target.

Abstract: This invention relates to an enzyme-controlled release method for the release of a leaving group comprising:contacting a compound represented by the formula ##STR1## wherein R, R.sub.1, R.sub.2 and R.sub.3 each independently is hydrogen, a substituent affecting the mobility or reactivity of the compound or a substituent including a biologically active group;X is leaving group;Z is an enzyme substrate moiety;--CR.sub.2 R.sub.3 X is either ortho or para to the --O--Z moiety;with an active capable of cleaving said enzyme substrate moiety Z from said compound;whereby said leaving group X is released from said compound.

Abstract: There is provided a biological diagnostic assay system wherein a phenoxy-substituted naphthalene compound, such as phenoxynaphthalene sulfonate, or a salt thereof, is utilized to prevent plasma proteins such as serum albumin from binding to other components of the assay and/or to displace plasma proteins which have become bound to other components of the assay.

Abstract: A diagnostic assay module for analytical procedures in which an optical signal developed by interaction between a component in a sample fluid, such as an analyte in a biological fluid, and one or more reagents in a resilient assay element is read by optical means. The module includes a first member having one open side and a second member adapted to close the open side of the first member against a resilient assay element. The area of the assay element to which the sample fluid is applied and wherein the optical signal developed by the interaction of the sample component and the reagent(s) in the assay element is read is maintained in a substantially horizontal orientation by flexure developed between complementing ramp surfaces on the respective first and second members.

Abstract: A liquid transport system provides controlled flow of liquid in a liquid flow zone between two surfaces wherein one surface includes a plurality of projections, or raised areas, arranged substantially throughout the surface in the liquid flow zone and an aperture for allowing the introduction of liquid between the two surfaces. In a preferred embodiment the projections on the first surface are arranged in parallel spaced rows and parallel spaced columns. The second surface may be one surface of a layer of a diagnostic assay element.

Abstract: The present invention provides an enzyme controlled release system and prepared reactant by which an identifiable molecule may be released on demand through the action of an active enzyme. The controlled release system is useful for detection of an analyte of interest present in a test sample in picogram per liter quantities and may be employed in a variety of different modes of use including immunoassays, enzyme amplification systems and the release of pharmacologically active ligands.

Abstract: Electrical cells and batteries comprising cathodes formed as slurries of MnO.sub.2 and carbon in an organic solution of electrolyte in contact with a copper substrate, and sheet lithium anodes adhered to either a conductive plastic or a roughened copper substrate.