Abstract: A biosensor (102) for determining the presence or amount of a substance in a sample and methods of use of the biosensor (102) are provided. The biosensor (102) for receiving a user sample to be analyzed includes a mixture for electrochemical reaction with an analyte. The mixture includes an enzyme, a mediator and an oxidizable species as an internal reference.

Abstract: A biosensor (102) for determining the presence or amount of a substance in a sample and methods of use of the biosensor (102) are provided. The biosensor (102) for receiving a user sample to be analyzed includes a mixture for electrochemical reaction with an analyte. The mixture includes an enzyme, a mediator and an oxidizable species as an internal reference.

Abstract: A biosensor (102) for determining the presence or amount of a substance in a sample and methods of use of the biosensor (102) are provided. The biosensor (102) for receiving a user sample to be analyzed includes a mixture for electrochemical reaction with an analyte. The mixture includes an enzyme, a mediator and an oxidizable species as an internal reference.

Abstract: A biosensor (102) for determining the presence or amount of a substance in a sample and methods of use of the biosensor (102) are provided. The biosensor (102) for receiving a user sample to be analyzed includes a mixture for electrochemical reaction with an analyte. The mixture includes an enzyme, a mediator and an oxidizable species as an internal reference.

Abstract: A biosensor (102) for determining the presence or amount of a substance in a sample and methods of use of the biosensor (102) are provided. The biosensor (102) for receiving a user sample to be analyzed includes a mixture for electrochemical reaction with an analyte. The mixture includes an enzyme, a mediator and an oxidizable species as an internal reference.

Abstract: A biosensor (102) for determining the presence or amount of a substance in a sample and methods of use of the biosensor (102) are provided. The biosensor (102) for receiving a user sample to be analyzed includes a mixture for electrochemical reaction with an analyte. The mixture includes an enzyme, a mediator and an oxidizable species as an internal reference.

Abstract: A method and apparatus are provided for correcting ambient temperature effect in biosensors. An ambient temperature value is measured. A sample is applied to the biosensors, then a current generated in the test sample is measured. An observed analyte concentration value is calculated from the current through a standard response curve. The observed analyte concentration is then modified utilizing the measured ambient temperature value to thereby increase the accuracy of the analyte determination.

Abstract: Disclosed is an improvement to the method of determining the concentration of a hemoglobin adduct in a blood sample by the steps of assaying the blood sample for the total amount of hemoglobin, assaying the blood sample for the hemoglobin adduct, and dividing the hemoglobin adduct concentration by the total hemoglobin concentration. The improvement involves normalizing the measurement of the hemoglobin adduct to the total amount of hemoglobin in the blood sample.

Abstract: Apparatus and method are provided for determining the concentration of an analyte in a fluid test sample by applying the fluid test sample to the surface of a working electrode which is electrochemically connected to a reference electrode which surface bears a composition comprising an enzyme specific for the analyte. A mediator is reduced in response to a reaction between the analyte and the enzyme. An oxidizing potential is applied between the electrodes to return at least a portion of the mediator back to its oxidized form before determining the concentration of the analyte to thereby increase the accuracy of the analyte determination. Following this initially applied potential, the circuit is switched to an open circuit or to a potential that substantially reduces the current to minimize the rate of electrochemical potential at the working electrode. A second potential is applied between the electrodes and the current generated in the fluid test sample is measured to determine analyte concentration.

Abstract: A method for the determination of protein and creatinine in urine. An organic acid, in the form of its lithium salt, is dried onto a suitable substrate in the second reaction zone of a reaction vessel having a first reaction zone for the immunometric determination of the protein and a second reaction zone for the colorimetric determination of creatinine. After completion of the immunometric determination of the protein the dried organic salt is contacted with the urine containing creatinine resulting in solubilization of the organic acid salt as creatinine reactive reagent thereby facilitating the colorimetric determination of the creatinine.

Abstract: Analytical reaction cassette and method for performing sequential analytical assay procedures to determine the amount of an analyte in a liquid test mixture. The reaction cassette can be in the form of a substantially square container having a substantially horizontal axis of rotation and incorporated with one or more analytical reagents such that they are contacted with a liquid test mixture in a desired ordered sequence to perform a particular assay procedure. Corners provided by the substantially square configuration of the reaction cassette disrupt the flow of liquids disposed in the reaction cassette upon contact therewith to thereby agitate and mix such liquids. A liquid disposed in the reaction cassette is capable of being manipulated and mixed therein by rotating the reaction cassette about the horizontal axis at sufficiently low velocities wherein the transport of such liquid is noncentrifugal and due substantially only to gravitational force.

Abstract: Compositions and test articles comprisng ionophore of an optically active isomer of bis(12-crown-4-methyl)dialkyl malonate, wherein alkyl group is methyl and the second alkyl group has 4 to 20 carbon atoms, with a reporter substance incorporated in a hydrophobic carrier are disclosed.

Abstract: The synthesis and use of optically active isomers of bis(12-crown-4-methyl) dialkylmalonates as sodium specific ionophores is described. The synthesis of optically active isomers of hydroxymethyl 12-crown-4 useful in synthesizing ionophores is also described.

Abstract: A water-insoluble, crosslinked polyacrylamide copolymer is prepared having recurring monomeric residues of acrylamide, bisacrylamide or analogs thereof, and N,N'-bisacrylylcystamine or analogs thereof. The crosslinked copolymer can be formed into discrete particles having crosslinking disulfide groups on their external surface which can be reduced to provide activated particles having exposed chemically active sulfhydryl groups. The activated polyacrylamide particles are free of residual amino and carboxylic acid groups and can be reacted with suitable haptens and other biologically active substances to provide insolubilized forms thereof.