Reference reading in an analyzer

• US 5,067,093 A
• Filed: 01/24/1990
• Issued: 11/19/1991
• Est. Priority Date: 01/24/1990
• Status: Expired due to Term

• Current Assignee: Clinical Diagnostic Systems Inc.
• Original Assignee: Eastman Kodak Company
• Inventors: Przybylowicz, Catherine S., Carrozziere, Luigi A., Brill, Edwin W. Jr.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Ramirez, Ellis B.
• Application Number:
  US07/469,887
• Time in Patent Office: 664 Days
• Field of Search: 364/498, 364/571.01, 364/571.04, 364/571.08, 364/579, 364/496, 364/497, 356/243, 356/448, 422/64
• US Class Current: 702/19
• CPC Class Codes: G01N 2021/478 Application in testing analytical test strips
• CPC Class Codes: G01N 21/8483 Investigating reagent band test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04
• CPC Class Codes: G01N 2201/12753 and storage
• CPC Class Codes: G01N 2201/128 Alternating sample and standard or reference part in one path

Abstract

A method and apparatus are disclosed for reading a test element and a reference element in an incubator to insure that a) they are both read at the same wavelength and b) the reading at this wavelength of the reference element used to compare the test element reading, is the closest in point of time to the reading taken of the test element. In some cases, this requires the comparison with a reference element that is read after the reading of the test element.

Claims

1. In a method for quantitatively assaying for an analyte in a biological liquid, comprising the steps of

a) scanning with a light beam a test element bearing a sample of liquid having an analyte of unknown concentration;

b) scanning a reference element with said light beam;

c) detecting the amount of light diffusely reflected from said test element and said reference element;

d) filtering the light beam before or after reflection from said elements and before detection, at a preselected wavelength that is the same for both said test element and said reference element;

e) storing the detected amounts of diffuse reflection for each scanning of the reference element and test element, and

f) comparing the detected reflectance of the test element with said stored reference detected reflectance to determine how much analyte is present, said reference element being scanned repeatedly, each time for a predetermined multiple of test elements scanned, a reference reflectance value being stored for each scanning;

the improvement wherein said step e) comprises the steps of always selecting from said stored reference reflectance detections at said wavelength that which is either detected by step c) at a point of time closest to the time at which said test element is scanned at said wavelength in step a), or that which is computed to be the equivalent reference reflectance at the actual time the test element reflectance was read, and comparing said selected reference reflectance detection in said step f) with the detected test element reflectance, whereby the effect of drift in the reading of the reference element is minimized.

2. A method as defined in claim 1, wherein said test elements and said reference element are held on a rotating surface and are moved past said light beam repeatedly by rotating said surface.

3. A method as defined in claim 1, wherein each of said test elements is scanned five times at said selected wavelength.

4. A method as defined in claim 1, wherein said reference element is read at at least two different wavelengths.

5. In an analyzer for quantitatively assaying for an analyte of a biological liquid, the analyzer including a) means for scanning with a light beam a test element bearing a sample of liquid having an analyte of unknown concentration;

b) means for scanning a reference element with said light beam;

c) means for detecting the amount of light diffusely reflected from said test element and said reference element;

d) means for filtering the light beam reflected from the elements at a preselected wavelength that is the same for the test element and the reference element;

e) means for storing the detected amounts of diffuse reflection for each scanning of the reference element and of the test element; and

f) means for comparing the detected reflectance of the test element with said stored reference detected reflectance at said selected wavelength to determine how much analyte is present, said reference element being scanned repeatedly, each time for a predetermined multiple of test elements scanned;

the improvement wherein said analyzer further includes means for always selecting from the stored reference reflective detections, either the value detected at the point of time that is closest to the time at which said test element is scanned by said scanning means a), or that which is computed to be the equivalent reference reflectance at the actual time the test element reflectance was read, and for supplying this value to said comparing means f), whereby the effect of drift in the reading of the reference element is minimized.

6. An analyzer as defined in claim 5, and further including a rotating support for said elements and means for rotating said support so that each element is scanned by said light beam repeatedly.

7. An analyzer as defined in claim 5, wherein each of said test elements is scanned five times at said selected wavelength.

8. An analyzer as defined in claim 5, wherein said scanning means scans said reference element at least two different wavelengths.