Abstract: A method of validating measurement of a kinetic chemical reaction comprises a first tier of validation to validate the ability of a measurement and detection system to provide accurate data, a second tier of validation to validate the initiation and control of the kinetic chemical reaction and a third tier of validation which verifies first that the expected kinetic chemical reaction has proceeded in a characteristic manner and direction, and second, that parameters of the chemical reaction are within limitations characteristic of the measurement and detection system of a measuring instrument investigating the reaction.

Abstract: An immunoassay for assaying an antigenic substance (Ag) in a fluid. The immunoassay is the type which comprises contacting the fluid with at least one first entity selected from a group consisting of an antibody (Ab) to the Ag, a soluble, labeled antibody (L-Ab.sub.a) to the Ag, and an antibody (Ab.sub.b) to the Ag bound to a solid support (SC). The immunoassay is characterized in that the fluid is contacted with at least one additional entity selected from a group consisting of at least one different type of soluble, labeled antibody (L-Ab.sub.c) to the Ag, at least one different type of antibody (Ab.sub.d) bound to a solid carrier (SC.sub.1), and at least one different type of antibody (Ab.sub.e) to the Ag. The SC.sub.1 is selected from a group consisting of SC, at least one different solid carrier (SC.sub.2), and mixtures thereof (SC and SC.sub.2). Each type of L-Ab.sub.c, Ab.sub.d -SC.sub.1, and Ab.sub.e has a lower average affinity constant (K) for Ag than each respective K of L-Ab.sub.a, Ab.sub.

Abstract: A direct particle agglutination immunoassay for assaying an antigenic substance (Ag) in a fluid. The immunoassay is the type which comprises:(a) contacting the fluid with an antibody (Ab) coated particle (P) to agglutinate the Ab coated particles; and(b) detecting the presence of agglutination.The immunoassay is characterized in that the fluid is contacted with at least one additional entity selected from a group consisting of at least one different type of antibody (Ab.sub.a) coated particle (P.sub.1) and at least one different type of antibody (Ab.sub.b). The P.sub.1 is selected from a group consisting of P, at least one different particle (P.sub.2), and mixtures thereof (P and P.sub.2). Each type of Ab.sub.a -P.sub.1 and Ab.sub.b has a lower average affinity constant (K) for Ag than the K of Ab-P and the additional entity is present in an amount sufficient to avoid a high antigen false negative effect.Also, a reagent of the type comprising Ab-P.

Abstract: A zero backlash device. The device includes a spring loaded bracket for providing a lateral force to the driving nut on a threaded rod. This lateral force is directed perpendicularly to the axis of the threaded shaft thus insuring continued intimate contact between the threads on the driving nut and the threads on the shaft.

Abstract: A substrate solution comprising (a) a substrate selected from a group consisting of salts of L-.gamma.-glutamyl-p-nitroanilide and L-.gamma.-glutamyl-3-carboxy-p-nitroanilide; and (b) a polyol selected from a group consisting of alkyl polyols containing 2 to 10 carbon atoms and 2 to 10 hydroxy groups and polyethylene glycol having an average molecular weight of from about 200 to about 600.Also, a kit for the determination of .gamma.-glutamyltransferase activity of the type comprising (a) a buffered medium comprising a buffer and a .gamma.-glutamyl residue acceptor; and (b) a substrate solution; the buffered medium and substrate solution being adapted such that preselected aliquots thereof can react in the presence of .gamma.-glutamyltransferase to produce an absorbing cleavage product. The kit is characterized in that the substrate solution is as described above.In addition, a method for determining .gamma.

Abstract: An apparatus and method for indicating the temperature of the environment into which a reaction vessel may be placed is provided by a container holding a thermally efficient fluid. The container has an identical external configuration substantially identical to the reaction vessel and is adapted to be positioned within the environment in place of the reaction vessel. A temperature sensor in thermal communication with the thermally efficient fluid provides an electrical parameter indicating the temperature of such fluid and thus the environment of the reaction vessel.

Abstract: A shear valve obtaining selective fluidic communication between fluid ports formed in a first member and fluid ports formed in a second member comprises a first seal with means for providing a fluidic seal between aligned ports and which separates the first and second members to form a passage, and a second sealing means to obtain a fluidic seal between the first and second members and enclose the passage. A fluid port is provided to introduce wash solution into the passage formed between the first and second members and a drain port is provided to remove the wash solution introduced between the first and second members, so that a wash and purge operation may be performed to cleanse the sealing surfaces of the valve.

Abstract: A kinetic assay method and apparatus for performing such method wherein a first sample containing predetermined concentrations of binary analytes is reacted with the reagent to form a reaction product. Reaction rates at first and second times are measured for the first reaction and a first ratio between such measured reaction rates is determined. A second reaction with a second sample and the reagent is also performed wherein the second sample contains predetermined concentrations of the binary analytes. Reaction rates at the first and second times are measured for the second reaction and a second ratio between such rates is determined. A third reaction with a third sample and the reagent is performed, the sample including unknown relative concentrations of the first and second analytes. Reaction rates are again measured at the first and second times and a third ratio between such measured reaction rates is determined.