Abstract: Disclosed is an improvement in the analysis for an analyte in a urine test sample in which the urine is contacted with a labeled antibody specific to the analyte and the concentration of the analyte is determined by measuring the response from the label. The improvement involves maintaining the concentration of urea in the test sample above the threshold value which value is the concentration of urea at which increases in the urea concentration do not affect the accuracy of the assay such as by interfering with the binding between the analyte and the labeled antibody.

Abstract: Disclosed is a method for determining the concentration of an analyte in a sample of body fluid. The method involves contacting the body fluid sample with a test strip containing mobile, labeled specific binding partner for the analyte, through which strip the test fluid, analyte and any complex formed by interaction of the analyte and labeled specific binding partner therefore can flow by capillarity. The strip contains at least one zone for capture of the labeled specific binding partner and at least one separate zone for retention of the analyte/labeled specific binding partner complex. By determining the magnitude of the signal from the detectable label in the capture zone(s) and retention zone(s) and determining a final response signal by correlating signals using an algorithm and number of zones chosen in a manner that provides a final response signal best suited for the particular assay, the concentration of the analyte can be determined with greater precision.

Abstract: Disclosed is a method for the immobilization of an analyte such as deoxypyridinium (DPD) onto a solid support. The method involves binding an antigen-amino acid-deoxypyridinium complex to the support via an anti-antigen binding partner located in a capture zone of the solid support. Preferably, the support is nitrocellulose and the antigen has the fluorescein structure.

Abstract: Disclosed is an improvement to the technique for immobilizing an analyte onto a solid surface for use in a competitive immunoassay. The improvement involves immobilizing the analyte on the solid surface by reacting the analyte or derivative thereof with polyethylene glycol which has been functionalized with a group which is reactive with the analyte contacting the resulting conjugate with the solid surface to thereby immobilize the analyte.

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 a method for the determination of creatinine in urine which involves contacting a urine test sample with a reagent system containing Cu.sup.+2, a hydroperoxide and an oxidizible dye which provides a detectable response when oxidized in the presence of a pseudoperoxide. The reagent system also includes a buffer to maintain the urine's pH within the range of 6.6 to 8.0 and a chelating agent for the cupric ions to prevent oxidation of the dye in the absence of creatinine.

Abstract: Use of a lithium salt, particularly lithium thiocyanate, as an agent for lysing red blood cells and denaturing hemoglobin in the performance of an immunoassay to detect the relative amount of a hemoglobin derivative in a blood sample. The method is particularly useful in the determination of hemoglobin Alc. The method provides a rapid means for releasing hemoglobin from red blood cells by lysis and for exposing the epitope that is characteristic of the Alc form. Low concentrations of the lithium salt provide rapid release and denaturation of hemoglobin without the need for dilution prior to the performance of the immunoassay.

Abstract: Chromogenic merocyanine enzyme substrate compounds of the general formula: ##STR1## where Y is an enzymatically-cleavable group such as a radical of a sugar, carboxylic acid, amino acid, peptide, phosphoric acid, or sulfuric acid; A and B represent residues that complete 5- or 6-membered ring systems; R.sup.1 is substituted or unsubstituted alkyl; R.sup.2 and R.sup.3, independently, are hydrogen or lower alkyl; m, n, and p, which can be different, are integers from 0 through 3 provided that m+n+p must be at least 2; and X is an appropriate counterion (anion).

Abstract: Use of a lithium salt, particularly lithium thiocyanate, as an agent for lysing red blood cells and denaturing hemoglobin in the performance of an immunoassay to detect the relative amount of a hemoglobin derivative in a blood sample. The method is particularly useful in the determination of hemoglobin A1c. The method rapidly releases hemoglobin from red blood cells by lysis and exposes the epitope that is characteristic of the A1c form. Low concentrations of the lithium salt provide rapid release and denaturation of hemoglobin without the need for dilution prior to the performance of the immunoassay.

Abstract: Chromogenic merocyanine enzyme substrate compounds of the general formula: ##STR1## where Y is an enzymatically-cleavable group such as a radical of a sugar, carboxylic acid, amino acid, peptide, phosphoric acid, or sulfuric acid; A and B represent residues that complete 5- or 6-membered ring systems; R.sup.1 is substituted or unsubstituted alkyl; R.sup.2 and R.sup.3, independently, are hydrogen or lower alkyl; m, n, and p, which can be different, are integers from 0 through 3 provided that m+n+p must be at least 2; and X is an appropriate counterion (anion).

Abstract: A stable test device for the determination of a peroxidatively active substance comprising a carrier containing 1,4-diisopropylbenzene dihydroperoxide and a benzidine indicator in a molar ratio of from 0.9 to 3.0. The composition can be incorporated in a carrier matrix along with a ferric chelate to provide ascorbate resistance thereto, which is important in a urine test for occult blood. The test device is stable under storage and heat stress and can be used to prepare a multitest strip containing a glucose test based on a peroxidase/potassium iodide indicator system.