Abstract: An assay device and method for determining the concentration of low density lipoprotein (LDL)-associated cholesterol (LDL-C) in a body-fluid sample, such as a blood sample is described.

Abstract: An assay device and method for measuring the concentration of HDL-associated cholesterol in a blood-fluid sample are described. The assay design prevents interference by reagents used for such removal with the HDL quantification reaction or with other assays carried out on the same sample. If desired, removal of non-HDL lipoproteins and assay of HDL cholesterol can be carried out without interruption of the assay.

Abstract: An assay device and method for measuring the concentration of LDL-associated cholesterol in a blood-fluid sample are described. The method employs selective precipitation of VLDL and chylomicrons and immunoseparation of HDL from a blood fluid sample. The assay device allows the assay to be performed entirely in a flow strip format.

Abstract: An assay device and method for measuring the concentration of HDL-associated cholesterol in a blood-fluid sample are described. The assay design is such that removal of non-HDL lipoproteins from a sample and assay of HDL cholesterol in the sample occur without interruption of the assay. The device also prevents interference by reagents used for the HDL assay with other assays carried out on the same sample.

Abstract: An assay device and method for determining the concentration of low density lipoprotein (LDL)-associated cholesterol (LDL-C) in a body-fluid sample, such as a blood sample is described.

Abstract: An immunoassay cassette, apparatus, and method for detecting an analyte in a liquid body-fluid sample are disclosed. The cassette has a body and a support mounted on the body, for movement relative to the body to first and second transfer positions. Sample supplied to a sample well in the cassette body is transferred to a reagent reservoir on the cassette body, by moving the support to its first transfer position. Here the sample reacts with a first reagent composition in the reservoir effective to form a modified sample. The modified sample is then transferred to a reagent strip on the support by moving the support to its second transfer position. The reagent strip has a transfer zone at which sample material is transferred to the strip, a second reagent composition effective to react with the modified sample to form a detectable analyte-dependent product, and a detection zone located downstream at which the detectable product can be observed.

Abstract: An immunoassay cassette, apparatus, and method for detecting an analyte in a liquid body-fluid sample are disclosed. The cassette has a body and a support mounted on the body, for movement toward and away from a sample transfer position. Sample supplied to a sample well in the cassette body is taken up by a reagent reservoir containing a first reagent composition effective to form a modified sample. The support provides a reagent strip having a transfer zone that is brought into contact with the reservoir, when the support is in the transfer position, a detection zone located downstream of the transfer zone, and a second reagent composition effective to react with the modified sample to form a detectable analyte-dependent product. By controlling movement of the support, volume and rate of sample flow from the reservoir to the strip can be controlled to optimize and/or standardize sample-transfer conditions in the assay.

Abstract: An assay pad for measuring the concentration of HDL-associated cholesterol in a sample, a method for using the pad, and a diagnostic assay device for carrying out the method are described. The assay pad includes a polymer adhesive or heat laminate bond. The assay design prevents interference by reagents used for such removal with the HDL quantification reaction or with other assays carried out on the same sample. If desired, removal of non-HDL lipoproteins and assay of HDL cholesterol can be carried out without interruption of the assay.

Abstract: An assay device and method for measuring the concentration of HDL-associated cholesterol in a blood-fluid sample are described. The assay design is such that removal of non-HDL lipoproteins from a sample and assay of HDL cholesterol in the sample occur without interruption of the assay. The device also prevents interference by reagents used for the HDL assay with other assays carried out on the same sample.

Abstract: The invention relates to an immunoassay cassette useful for carrying out multistage immunoassays in an automated manner. In operation, the cassette assumes different operational positions in which solutions are transferred sequentially across an absorbent pathway containing assay reagents.

Abstract: An assay device for measuring the concentration of HDL-associated cholesterol in a blood-fluid sample is disclosed. The device includes a glass-fiber sieving matrix capable of separating soluble and precipitated material migrating through the matrix, and a reagent reservoir in the matrix, for releasing a reagent effective to selectively precipitate LDL and VLDL particles, while permitting soluble HDL to migrate through the matrix. The glass fibers are coated with a polymer coating to prevent binding of HDL to the fibers in the presence of the precipitating reagent.

Abstract: An assay device and method for measuring the concentration of HDL-associated cholesterol in a blood-fluid sample. The device includes a glass-fiber sieving matrix capable of separating soluble and precipitated material migrating through the matrix, and a reagent reservoir in the matrix, for releasing a reagent effective to selectively precipitate LDL and VLDL particles, while permitting soluble HDL to migrate through the matrix. The glass fibers are coated with a polymer coating to prevent binding of HDL to the fibers in the presence of the precipitating reagent.

Abstract: An improved method for measuring the concentration of HDL-associated cholesterol in a blood-fluid sample. The method includes (a) adding a volume of the sample to an absorptive matrix (i) formed of glass fibers and (ii) effective to separate soluble from precipitated blood through the matrix from a sample-application site to a sample-collection site in the matrix, (b) releasing into the matrix, dextran sulfate and magnesium ions in an amount effective to selectively precipitate LDL and VLDL in the fluid sample, and (c) assaying fluid sample which has migrated through the matrix for the presence of lipoprotein-bound cholesterol. The improvement in the method comprises treating the glass fibers by reaction with bis(hydroxyethyl)aminopropyltriethoxy silane or by coating the fibers with polyvinyl alcohol, thereby affording substantially 100% recovery of HDL applied to the matrix.

Abstract: An assay device for measuring the concentration of a soluble analyte, such as HDL-associated cholesterol, in a fluid sample containing interfering compounds, such as LDL-or VLDL-associated cholesterol, which can be selectively precipitated. The device includes a sieving matrix capable of separating soluble and precipitated material migrating through the matrix, and a reservoir which holds a precipitating agent which is effective, within a given concentration range, to selectively precipitate the interfering compounds. The reservoir is designed to delay the release of agent, on contact with the fluid sample, to maintain the concentration of precipitating agent in contact with the fluid sample within the given concentration range.

Abstract: An assay device and method for determining the concentration of an analyte in a fluid sample. The device includes a porous-matrix reservoir which receives the sample to be assayed, and at least two reaction zones into which sample fluid is drawn from the reservoir. In an embodiment containing two reaction zones, a single-point standard curve which corrects for reduced-signal effects related to loss of reagent activity and linear inhibition effects, is used to determine analyte concentration. In an embodiment containing three reaction zones, a two-point standard curve which corrects for reduced-signal effects related loss of reagent activity and non-linear inhibition effects, is used to determine analyte concentration. Also disclosed is an apparatus which uses the device for automated or semi-automated analyte assay.

Abstract: An assay device and method for determining the concentration of an analyte. Analyte introduced by liquid absorption into the matrix is used to generate H2O2, via an analyte-specific oxidase, and the H.sub.2 O.sub.2 is utilized by peroxidase in the presence of peroxidase to convert a substrate reagent to a colored reaction product. A trapping compound in the matrix competes with the substrate reagent, in the presence of the peroxidase enzyme, to produce a silent reaction product, thus proportionately reducing the amount of signal reaction product generated by a given amount of analyte. Detection of a wider range of analyte concentrations is therefore possible.

Abstract: Method and apparatus for use in determining the concentration of a selected analyte in a body-fluid sample. As the fluid sample is applied to a wettable, absorbent reaction pad, the extent of sample wetting of the pad is monitored by surface reflectance. This surface monitoring is used to control the volume of sample applied to the pad, to prevent overfilling the pad and to allow determination of the final sample volume applied. From the known sample volume and amount of analyte, the concentration of analyte in the sample can be accurately calculated in reaction components, trapping agents, matrix configuration, and analyte tested can be made.

Abstract: An assay device for assaying multiple analytes in a drop-size blood sample. The device includes a sample dispenser designed to distribute a small-volume blood sample to multiple transfer sites, by capillary flow of the blood sample through sieving and distributing matrices which separate blood cells from serum as the sample fluid migrates toward the transfer sites. A test plate in the device carries multiple absorbent test pads, each containing reagent components for use in detection of a selected analyte. The test plate is mounted on the dispenser for movement toward and away from a transfer position at which the exposed surface regions of the pads are in contact with associated sample-transfer sites, for simultaneous transfer of sample fluid from such sites to the pads in the support.