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: 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.

Abstract: Immunoassays featuring voltammetric measurements wherein at least one of the immunoreactants is labelled with an electroactive substance. Measurement is effectedon a pulsed-basis to maximize the signal change due to the electron transfer capabilities of the labelled immunoreactants.

Abstract: A multichamber cuvette for maintaining in independent and separate condition at least two reactants until such time that it is desired to mix them for reaction with each other and a reactant liquid sample while in the cuvette for analysis in the cuvette, and a method of use of such cuvette. There is provided a cuvette body of a suitable plastic defining at least two chambers interconnected by a passageway of relatively small cross section having at least the end portion thereof of capillary size to prevent under many circumstances, as by surface tension, accidental mixture of liquid reactants in the chambers. If there is a substantial head of liquid in one chamber and/or a risk of impact of the cuvette with an external foreign object, sufficient to break such surface tension, an air lock in the passageway when the latter is below the liquid levels in the chambers prevents such accidental mixture. A baffle in the passageway enhances separation of liquids and/or solid substances in the chambers.

Abstract: A disposable integrated miniaturized array of chemical sensors for analyzing concurrently a number of analytes in a fluid sample is described. Each sensor is a complete electrochemical cell consisting of its own individual reference and indicator electrodes and is selective with respect to a particular analyte in the sample.Where required, a sensor can be individually calibrated, such that each analysis can be read directly.

Abstract: A carbohydrate substrate such as starch for a carbohydrate hydrolyzing enzyme is immobilized on a solid inorganic porous support to form a stable substrate-support composite useful in affinity chromatography and in methods where a precise amount of substrate is needed to perform an enzyme-substrate reaction to quantify the enzyme. The substrate may be activated with an agent such as cyanogen bromide or imidazole prior to deposition on the support so that it may be effectively modified while on the support. After deposition, the substrate is modified by reaction with an epoxyhalogen, aliphatic dihalide or aliphatic diamine to aid in holding it on the support. In an alternative embodiment, the carbohydrate, prior to deposition and modification on the support, is hydrolyzed with an enzyme, preferably dextranase.

Abstract: New and improved method and apparatus for the non-invasive detection of the respective segments and segment interfaces, and the non-invasive determination of the respective segment volumes, of a continuous segmented fluid stream flowing in a transparent conduit are disclosed and comprise means to irradiate the conduit and the flowing fluid stream with radiation energy of spectral content predetermined in accordance with the radiation energy absorbance and refraction characteristics of the fluid segments and the fluid segment-conduit interface, means to detect the radiation energy which is transmitted through the segments and conduit and provide signals indicative thereof, and signal processing means operatively associated with the detecting means and operable to process said signals and perform the stated functions in accordance therewith.

Abstract: A system for detecting live insects in a commodity sample features forming a closed-loop between a stored quantity of fluid and a sample cell and a reference cell. The closed-loop and the stored fluid ensure a controlled environment during incubation and analysis of the commodity sample. This controlled environment achieves a greater sensitivity and reproducibility than prior systems.

Abstract: A method of producing an immobilized protein composite, i.e. enzymes such as glucose oxidase, on an alumina support, comprising modifying some of the free functional groups of the protein such as amino groups, by reaction with an acid or anhydride, depositing the modified protein on a porous inorganic support at controlled pH and temperature, and cross-linking remaining free functional groups of the protein with adjacent deposited protein functional groups to form interprotein peptide bonds. The resultant composite has long-term continuous use.

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.