Abstract: Methods and apparatuses are featured for analyzing whole blood samples by diffusion techniques in porous media. A fluid component of the whole blood is diffused into a thin-film porous medium of a given predetermined volume. Hematocrit dependent errors in diffusion time do not pose a problem in obtaining a precise aliquot of the fluid component of the whole blood due to rapid diffusion and saturation of the fluid component into the porous medium.In another embodiment, diffusion switches or valves allow for precise aliquots in porous media by control of the diffusion and/or reaction of sample analyte with reagents.

Abstract: Methods and apparatuses are featured for preconcentrating immunological reactants prior to their contact and reaction, to greatly enhance the rate of reaction and the sensitivity. The preconcentration is accomplished within the reaction medium and is followed automatically by the separation of unreacted and reacted reactants resulting in a simplified and compact apparatus.

Abstract: Biological fluids, such as serum, are analyzed for the presence, nature and/or amount of antibodies, antigens and antibody:antigen complexes therein using as a reagent, insolubilized rheumatoid factor or insolubilized Clq. These reagents are themselves novel. They bind to antibody:antigen complexes, but not to free antibodies or antigens, and complexes can thus be removed from mixtures thereof with other materials, such as antibodies and antigens.

Abstract: A method and apparatus for performing a chemiluminescent immunoassay featuring electrochemical techniques to generate an oxidant used to trigger the chemiluminescence of the labelled immunoreactant. The generation of the oxidant is precisely controlled and the oxidant precisely and uniformly delivered to provide a more accurate, precise and sensitive assay.

Abstract: A particle agglutination assay for antigens, antibodies and other binding proteins such as rheumatoid factor, uses two different, microscopic or submicroscopic particulate reagents. The first particulate reagent binds with the antigen or antibody under assay, and then the second particulate reagent is added which binds only to those first reagent particles which have bound to the antigen or antibody under assay, so causing agglutination. The free unbound first or second particles are assayed to indicate the presence and/or amount of the antigen or antibody under assay. The assay of rheumatoid factor may be so conducted to reveal the fractions of each immunoglobulin class of RF present. The assay is particularly useful for small quantities of antibodies present in human sera indicating allergy, infection or autoimmune diseases.

Abstract: A fluid sample cell comprising a sample compartment of precisely predetermined depth bounded by opposed surfaces of a transparent window and a diffuse mirror is disclosed, and comprises inlet and outlet ports for the flow of a series of successive samples into and through said sample compartment and the spectroscopic analysis thereof by irradiation and detection of transmitted and reflected radiation.

Abstract: A method for labelling a histological specimen, wherein such specimen is embedded in a paraffin block along with an integral set of supported elongated elements identifying such specimen for subsequent sectioning on a microtome. The identification elements are sectioned concurrently with the specimen, so as to form an integral part of the section.

Abstract: An apparatus and method for increasing the throughput of a chromatographic system by passing several samples in seriatim through tandemly connected first and second chromatographic columns. The eluant from the first column is sampled, or fractionated, and fractions of each of the samples are passed through the second column for further separation. A switching of the sampling valve, disposed between the first and second columns, effects such fractioning. The pumping rate for the second column may be different from that of the first column and allows that two or more sample fractions can occupy the second column concurrently. Column efficiency or separation power of the system can be further increased by continuously recycling the fractions through the second column or passing such fractions through a third column which forms a continuous cyclic flow path with the second column via appropriate valve switching. Recycling can be continued until complete separation is achieved.

Abstract: A keyboard is constructed as an integral member of a display screen. The keyboard comprises a number of keys which are back-lighted upon the screen when they are enabled, but which are otherwise invisible to the viewer when disabled. When a key is depressed, the lit keyboard is reconfigured, a new set of keys enabled, and a system function is performed.

Abstract: Thyroid hormones such as thyroxine and triiodothyronine are assayed in biological fluid samples by a competitive binding analysis in which a fluorescent label is used. Upon formation of complexes, the fluorescence of the labelled compound is released, and the hormone can be assayed by measuring the fluorescence of the mixture and comparing the result with standard data. Fluorescein is the preferred label. The process can be operated in a continuous flow manner.

Abstract: A method of transferring a substance adhering to the surface of a substrate to a receiving surface of a backing element which includes locating the substrate surface in juxtaposition with the receiving surface, supplying a transfer medium on the receiving surface in sufficient quantity to encapsulate the substance, joining the transfer medium on the backing element with a substance so as to encapsulate the substance within the transfer medium and removing the substrate to expose the encapsulated substance.

Abstract: There is disclosed a method and apparatus for obtaining a precise aliquot of a sample by diffusing the sample into a gel mass for a controlled period of time. The sample may comprise a liquid containing an unknown quantity of a diffusible, to-be-assayed, component or components. The method may further include reacting a component of the sample with an assay-reagent present in excess quantity above that needed for reaction, the reagent being disposed in the gel mass. The sample is placed in contact with a preselected surface area of the gel mass. The component of the sample is allowed to diffuse into the gel mass for a controlled period of time. Thereafter, the remainder of the sample containing the component is removed, and further diffusion of the component through the gel mass may proceed for a controlled period of time. This provides both a further dilution of the component and permits continuous reaction of the component with a reagent distributed throughout the gel mass.

Abstract: Contamination between successive aqueous samples in a continuous-flow analytical system is eliminated by the careful and precise application of a thin, uniform film of immiscible fluid upon the outer surface of an aspirating probe of a metering system. The immiscible fluid is selected to preferentially wet the inner and outer probe surfaces and the inner wall surfaces of the conduits of such system, to the substantial exclusion of the aqueous samples. The immiscible fluid is aspirated, along with an air segment, between aspirations of successive samples, each aspirated air and sample segments are encapsulated by such immiscible fluid while passed through such system. A selective valve is utilized to isolate and transfer each fluid sample from the probe to such system.

Abstract: Apparatus for permanently and protectively mounting "wet" thin sections of biological specimens on microscope slides, wherein each specimen is initially bathed in a low-volatile solvent containing a low concentration of first polymerizable material. Such solvent is allowed to evaporate, whereby the liquid polymerizable material permeates and protects the specimen. Following solvent evaporation, a second polymerizable material is layered over the specimen. Preferably, the first and second polymerizable materials comprise a mixture of low-volatility, low-viscosity, liquid acrylic reactomers and a U.V. light-sensitive catalyst system. A conventional cover slip or other planar transparent member can be positioned over the polymerizable materials, and the same are polymerized by exposure to U.V. radiation. The first and second now-polymerized materials encapsulate the specimen on the microscope slide, become integral and completely hardened and are fully devoid of any solvent.

Abstract: Insolublized antibodies, F(ab').sub.2 fragments thereof and protein antigens are made by coupling to a water-insoluble substrate using a bridging agent which covalently binds to sulphur atoms in antibody, fragment or protein rather than to free amino groups therein. This is preferably effected by using a chloracetyl-terminated bridging agent. Immunoassays utilizing these insolubilized reagents are described. One novel class of bridging agents comprising anhydride and monochloracetyl end groups, which is useful for making the said reagents, is also disclosed.

Abstract: A sample analyzing system features a number of discrete sample segments continuously conveyed along a conduit. Each sample segment receives a precise aliquot of one or more reagents on a selective basis, and in any particular sequence. Selective injection of the reagent into the moving stream of sample segments allows for an increase in the efficiency and throughput of the sample processing.

Abstract: Method and apparatus for analyzing whole blood samples which feature impregnating a gel medium used for the analysis of the whole blood sample with an inert substance. When the whole blood sample is placed on the gel medium, the inert substance diffuses from the gel as the plasma solutes of the blood diffuse into the gel. The amount of the inert substance diffusing from the gel medium is inversely proportional to the hematocrit of the blood sample. In one embodiment, plasma solutes are caused to react with one or more reagents in the gel medium to assay various specific analytes. Also, the hematocrit, indicated by the diffusion rate of the inert substance from the gel, is determined and used to correct such assay.

Abstract: A method for the quantitative determination of sugars in a fluid sample. The sugar sample, which may contain free glucose, is passed through a scavenger stage where substantially all of the glucose is removed, so that it does not interfere with the determination. The glucose-free sample is then passed through an immobilized glucose generating stage to produce glucose in molar proportion to the total initial concentration of the sugars present. The generated glucose is passed through an immobilized hydrogen peroxide generating stage to form gluconic acid and hydrogen peroxide. The generated hydrogen peroxide is detected in suitable detection means, typically a polarographic cell. Total free glucose is determined by measuring the total sugars in the sample by bypassing the scavenger stage, determining total sugar, then determining the glucose in the sample without bypassing the scavenger and measuring free glucose as the difference.

Abstract: A separator and method, particularly for use in continuous-flow analysis, for separating liquid from a mixture of a liquid phase and a solid phase. The separator includes a first conduit, and a second conduit which communicates with the first conduit across a filter, whereby liquid in the liquid-solid phase mixture in the first conduit can be pumped into the second conduit, the solid phase being held back by the filter, the filter then being back-washed with wash liquid. The liquid-solid phase mixture may be segmented, the segments being separated by occluded air, or air and wash liquid segments, the back-washing then being controlled to occur while the air and/or wash liquid traverses the filter.

Abstract: An infrared analyzer is described which analyzes constituents of a sample. The sample and/or reference signals are synchronously averaged to provide unisonous sample and reference values. This processing eliminates drift and signal noise from the measurements, thus providing a more sensitive and accurate characterization of the constituents of the sample.