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: Disclosed is a method for cleaning optical surfaces, such as those in a urine analyzer, which surfaces come into repeated contact with urine test samples. The method involves contacting the optical surfaces with an aqueous solution of a quaternary ammonium or phosphonium salt, a non-ionic surfactant and a divalent ion.

Abstract: Disclosed is an improvement to the assay for creatinine in fluid test samples by contacting the test sample with a reagent formulation containing cupric ions, a hydroperoxide and an oxidizable dye. The improvement involves the inclusion of one or more selected quinolines in the reagent formulation. When the quinoline is substituted with methyl in the 2-5 position and/or a methoxy in the 2-6 position auto-oxidation of the oxidizable dye is reduced. When the quinoline is further substituted in an otherwise unsubstituted carbon atom in the 2-8 position, the assay's resistance to interference from hemoglobin and ascorbate is increased.

Abstract: A method for improving the accuracy of temperature sensitive diagnostic assays which are carried out using reflectance spectrometers to detect color changes in a solid test system which has been contacted with a fluid test system suspected of containing an analyte whose presence and/or concentration is being sought. The method involves determining the temperature of the solid test material by measuring the reflectance of a thermochromic liquid crystal in close proximity to the solid test material and correcting the result of the assay for a change in temperature from a pre-selected nominal temperature.

Abstract: Disclosed is an automated method for reading a test strip for the analysis of one or more analyte in a liquid test sample. The method involves the spectrophotometric reading of a test strip which bears at least two marker fields on its surface which are capable of reflecting light at different spectral regions from each other. The reading means of the spectrophotometer is programmed to discern information concerning the strip, such as what analyte the strip is designed to detect, from the sequences of spectral classifications by spectral reflectancy measurements of the strip's marker fields.

Abstract: Disclosed is an improved assay for the determination of total protein in an aqueous test fluid such as urine. The assay involves combining the test fluid with a molybdate or tungstate salt and a dye which forms a complex with molybdate or tungstate ion at a pH of 1.0 to 3.0 to shift the absorption band of the complex in the presence of protein. There is introduced into the assay a substituted phenolsulfonephthalein dye having a pKa which enables it to operate at a pH of from about 1.0 to 3.0 and whose affinity for protein is such that it will provide a detectable response only in the presence of greater than 50 mg/dL of protein to increase the scope of the assay.

Abstract: Disclosed are 6.alpha.-derivatized estriol compounds which, when conjugated to a protein, are useful in the in vivo preparation of antibodies specific to estriol. When labeled with a detectable label, the estriol derivatives are useful as haptens in a competitive immunoassay for estriol which demonstrate superior sensitivity with respect to estriol specific antibodies.

Abstract: Disclosed is an improved method for the detection of an analyte in a fluid test sample using a strip of a negatively charged matrix material having a zone containing mobile, labeled binding partner for the analyte and a separate zone for capturing the labeled binding partner as it is carried through this zone by the fluid test sample. The improvement involves combining the fluid test sample with a polyalkoxylated amine surfactant to control non-specific binding of the labeled binding partner to the negatively charged matrix material.

Abstract: Disclosed is an improvement to a sandwich type immunoassay in which there is immobilized to a solid support an antibody which is specific to an epitope of the analyte whose presence or concentration is being sought and a first labeled antibody which is specific to another epitope of the analyte. The improvement involves providing a second labeled antibody which is specific to the first labeled antibody to thereby form a chain of two or more labeled antibodies which results in amplification of the signal generated upon formation of the sandwich.

Abstract: A variety of diazacyanine mediators that are soluble in aqueous media and which do not inhibit enzymatic activity are provided for use on the surface of a working electrode of a electrochemical biosensor for electrochemical co-enzyme regeneration. The co-enzyme, dihydronicotinamide adenine dinucleotide (NADH) or dihydronicotinamide adenine dinucleotide phosphate (NADPH), is oxidized to NAD.sup.+ OR NADP.sup.+ which is reduced by an oxidoreductase such as a dehydrogenase acting on a substrate. By applying the mediator together with NADH or NADPH to the surface of the working electrode, the voltage necessary to achieve oxidation is substantially reduced. Biosensor electrodes such as graphite electrodes may be produced-by screen printing techniques.

Abstract: A method and apparatus are provided for calibrating a sensor for determination of analyte concentration. The meter includes a sensor for receiving a user sample to be measured and a processor for performing a predefined test sequence for measuring a predefined parameter value. A memory can be coupled to the processor for storing predefined parameter data values. A calibration code is associated with the sensor and read by the processor before the user sample to be measured is received. The calibration code is used in measuring the predefined parameter data value to compensate for different sensor characteristics.

Abstract: A sensor dispensing instrument is adapted to receive a generally circular sensor pack containing a plurality of blood glucose sensors. Each of the sensors are disposed in sensor cavities, each of which is in fluid communication with a corresponding desiccant cavity and has a support wall that assists in directing the sensor as its being ejected from the cavity. The sensor pack is loaded on an indexing disk in the instrument such that when a slide actuator on the instrument is moved toward a testing position, a feed mechanism engaged by the slide actuator moves a knife blade thereon toward one of the sensor cavities. The knife blade pierces a portion of a foil covering the sensor cavity and engages the sensor disposed in the cavity to thereby eject the sensor from the sensor cavity.

Abstract: The present invention involves a composition and method for the determination of enzymatic activity or enzyme substrate concentration in a fluid test sample in which the enzyme catalyzes a reaction in a reagent system to provide a detectable response indicative of the concentration of the enzyme or enzyme substrate in the test sample. A measured amount of a protease capable of eliminating the enzymatic activity is included in the reagent composition, so that when a measured amount of test sample is treated, the reaction producing the detectable response will have a definite end point. The invention is particularly useful in conjunction with the determination of leucocytes in urine wherein the leukocytes are lysed to release their human leucocyte elastase which hydrolyzes a chromogenic ester to provide a phenol which then reacts with a diazonium salt to form a colored azo dye.

Abstract: A system for normalizing measurements obtained from spectrometers to correct for measurement biases in individual spectrometers. The normalization system is adapted for use in spectrometers having an optical assembly for obtaining characteristic data from a test sample. A normalization factor is obtained in each spectrometer by placing a holographic dispersion filter between the light source and detector in the position normally occupied by the test sample, the filter having been encoded with a symbol representing a nominal value of light expected to pass through the filter. The spectrometer determines the value of light passing through the filter and calculates a normalization factor based on the ratio between the nominal value of the filter and the actual value obtained by the spectrometer. The normalization factor is stored in system memory and the filter removed so that the spectrometer may thereafter be used to evaluate a plurality of test samples.

Abstract: A sensor dispensing instrument is adapted to receive a generally circular sensor pack containing a plurality of blood glucose sensors. Each of the sensors are disposed in sensor cavities, each of which is in fluid communication with a corresponding desiccant cavity and has a support wall that assists in directing the sensor as its being ejected from the cavity. The sensor pack is loaded on an indexing disk in the instrument such that when a slide actuator on the instrument is moved toward a testing position, a feed mechanism engaged by the slide actuator moves a knife blade thereon toward one of the sensor cavities. The knife blade pierces a portion of a foil covering the sensor cavity and engages the sensor disposed in the cavity to thereby eject the sensor from the sensor cavity.

Abstract: The present invention concerns an electrochemical sensor made up of an insulating base having an electrode layer on its surface and a lid of deformable material which comprises a concave area in the central portion thereof, so that when it is mated with the base, the lid and base form a capillary space containing the electrode layer. When the electrode layer is in operative contact with a reaction layer comprising an enzyme which will cause the production of mobile electrons when contacted with a suitable analyte, the concentration of analyte, e.g. glucose in blood, can be measured by measuring the current created by the flow of mobile electrons when contacted with a suitable analyte, the concentration of analyte, e.g. glucose in blood, can be measured by measuring the current created by the flow of mobile electrons.

Abstract: In the case of the electrochemical enzyme biosensor comprising noble metal electrodes, an electrochemical oxidation of pyridine nucleotides takes place, in particular of NADH. The noble metal electrodes have a microtexture rich in surface pores and having catalytic properties, as a result of which the overpotential required for electrochemical oxidation of the pyridine nucleotides is reduced. Owing to these microtextures, the surface area of an electrode is from 3 to 10 times larger than its geometric surface area.

Abstract: Disclosed is an electrochemical sensor which is made up of an insulating base plate bearing an electrode on its surface which reacts with an analyte to produce mobile electrons. The base plate is mated with a lid of a deformable material which has a concave area surrounded by a flat surface so that when mated to the base plate there is formed a capillary space into which a fluid test sample can be drawn. The side of the lid facing the base is coated with a polymeric material which serves to bond the lid to the base plate and to increase the hydrophilic nature of the capillary space.

Abstract: The determination of lysozyme in urine is carried out by contacting the urine with a reagent system containing a buffer and a protein error indicator dye. Other proteins normally found in urine can compete with the lysozyme for interaction with the protein error indicator thereby affecting the specificity of the test for lysozyme. The present invention involves the addition of certain alkyl sulfonic acids or sulfonates to increase both specificity and sensitivity of the reagent for lysozyme.

Abstract: The determination of human serum albumin (HSA) in urine is carried out by contacting the urine with a reagent system containing a buffer and a protein error indicator. Other proteins normally found in urine can compete with the HSA for interaction with the protein error indicator thereby affecting the sensitivity of the test for HSA. The present invention involves the addition of certain polymeric competitive inhibitors to the reagent system which inhibit the interaction of the urinary proteins other than HSA with the protein error indicator to a greater extent than the interaction with HSA is inhibited thereby increasing the reagent's sensitivity for HSA. Suitable polymeric inhibitors include poly(vinyl alkyl esters), poly(alkyl acrylates), poly(vinyl alkyl carbonates) and poly(vinyl alkyl ketones).