Syva Company

Quidel Corporation

Mallinckrodt, Inc.

Henry K Tom

Richard B Mortensen

Gerald L Rowley

Carl P Kremer, Jr

Ann S Kremer

Daniel B Rosman

Gary A Ascani

Douglas D Rundle

An assay for determining the presence of a threshold concentration of an analyte in a sample comprises first reacting the sample with an amount of anti-analyte selected to reduce the free analyte to a marginally detectable concentration. The sample is then contacted with anti-analyte immobilized on a test region or indicator zone on a solid phase, whereby the residual free analyte may be bound. The binding of free analyte to immobilized anti-analyte is detected by a variety of techniques to indicate the presence of the threshold concentration. By employing limited amounts of anti-analyte on the solid phase, the change between maximum binding of label and no binding of label will be responsive to very small changes in the analyte concentration originally present in the sample.

Assay having improved dose response curve

A sample applicator for use in performing immunoassays comprises a tube defining an internal lumen and having a filter matrix at one end thereof. Sample is drawn into the applicator tube, either using a vacuum bulb or an automated assay device. The sample is filtered as it enters the tube, and is again filtered as it discharged from the tube in the opposite flow direction. By removing particulates from the liquid sample, assay performance can be greatly improved. The applicator may also comprise a reagent dispersed within a permeable matrix, which is useful for introducing reagent to a sample or other liquid assay component. As a liquid assay component is drawn into the applicator tube, the reagent is reconstituted by and mixed with the liquid, thereby reducing the number of steps required for the assay.

Method of sample transfer using a filter applicator

An improved nebulizer for substantially complete discharge of liquid before 'sputtering' occurs includes a housing having a mist outlet, and an aspirating structure including a nozzle having a base portion at one end thereof within the housing. The nozzle includes a nozzle outlet for discharge of gas under pressure within the housing at end of the nozzle opposite the base portion. The nebulizer further includes an inverted frusto-conical bottom wall disposed about the base portion of the nozzle away from the nozzle outlet, the bottom wall forming a liquid reservoir that drains towards the base portion of the nozzle. The aspirating structure also includes at least one passageway peripherally located with respect to the nozzle, the passageway communicating with the reservoir for aspiration of liquid from the reservoir in response to gas discharged from the nozzle to form a mist. A well that is in communication with the passageway is interposed between the bottom wall and the aspirating structure for collecting and concentrating liquid between the bottom wall and the aspirating structure to avoid 'sputtering' of liquid prior to substantially complete discharge of liquid from the nebulizer.

Non-sputtering nebulizer

A solid support 'dipstick' immunoassay impregnated with sodium metaperiodate (NaIO.sub.4) is described wherein ascorbate interference with an assay having a peroxidase signal producing system is reduced or eliminated.

Periodate removal of ascorbate interference in dipsticks for immunoassays

Method and apparatus are provided for performing immunoassays employing a device comprising a relatively small test zone referred to as an immunosorbing zone, and a relatively large liquid absorbing zone in liquid receiving relationship with said immunosorbing zone. The immunosorbing zone includes a member of an immunological pair ('mip')--ligand and antiligand--bound to a support. A signal producing system is employed in conjunction with said device having as one component a signal label bound to a mip. The signal producing system provides for production of a detectible signal in the immunosorbing zone in relation to the amount of analyte in a sample.

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La Honda, CA, United States of America

Henry K Tom