Method of reducing analysis time of endpoint-type reaction profiles

• US 20040078149A1
• Filed: 10/21/2002
• Published: 04/22/2004
• Est. Priority Date: 10/21/2002
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Matzinger, David
• Granted Patent: US 7,118,916 B2
• Time in Patent Office: Days
• US Class Current: 702/22
• CPC Class Codes: C12Q 1/00 Measuring or testing processes involving enzymes, nucleic acids or microorganisms measuring or testing apparatus with condition measuring or sensing means, e.g. colony counters, C12M1/34; Compositions therefor; Processes of preparing such compositions
• CPC Class Codes: G01N 21/79 Photometric titration
• CPC Class Codes: G01N 33/557 using kinetic measurement, i.e. time rate of progress of an antigen-antibody interaction
• CPC Class Codes: G16C 20/10 Analysis or design of chemical reactions, syntheses or processes
• CPC Class Codes: Y10T 436/11 Automated chemical analysis
• CPC Class Codes: Y10T 436/112499 with sample on test slide
• CPC Class Codes: Y10T 436/115831 Condition or time responsive
• CPC Class Codes: Y10T 436/12 Condition responsive control
• CPC Class Codes: Y10T 436/144444 Glucose
• CPC Class Codes: Y10T 436/147777 Plural nitrogen in the same ring [e.g., barbituates, creatinine, etc.]
• CPC Class Codes: Y10T 436/171538 Urea or blood urea nitrogen

Abstract

Methods, devices and kits for facilitating medical diagnostic assays and reducing the time required for taking of such assays. The methods comprise initiating a reaction, obtaining at least three measurements, at three different time points, of a value or level of an observable associated with the reaction, and estimating an end point value for the observable from the measurements.

Claims

1. A method for characterizing reaction end point, comprising:

(a) initiating a chemical reaction;

(b) obtaining at least three measurements, at three different time points, of a value associated with an observable indicative of progress of said reaction; and

(c) determining an end point value for said observable from said measurements.

2. The method of claim 1, wherein said end point value is determined according to the difference of an intermediate measured value, less a number equal approximately to the square of the difference between a later measured and an earlier measured value divided by a number equal approximately to an integer multiple of said later measured value less twice said intermediate measured value plus said initial measured value.

3. The method of claim 1, wherein said obtaining said measurements comprises taking said measurements at equal intervals of time.

4. The method of claim 1, wherein said chemical reaction comprises an analyte obtained from a bodily fluid.

5. The method of claim 4, wherein said observable is associated with concentration of said analyte in a reaction sample.

6. The method of claim 1, wherein said observable comprises an optically detectable species associated with said chemical reaction.

7. The method of claim 1, wherein said observable comprises an electrically detectable species associated with said chemical reaction.

8. A method for characterizing reaction end point, comprising:

(a) initiating a chemical reaction including an observable A indicative of extent of reaction,

(b) measuring first, second and third values A₁, A₂, and A₃ for said observable, at times t₁, t₂ and t₃ respectively; and

(c) determining an endpoint value A_∞

for said observable according to the relationship

$A_{\mathrm{\infty <br><br>}}\cong <br><br>A_2-\frac{{\left(A_3-A_1\right)}^2}{4<br><br>\left(A_3-2<br><br>\text{\hspace{1em}<br><br>}<br><br>A_2+A_1\right)}.$

9. The method of claim 8, wherein time interval t₂−

t₁ is equal to time interval t₃−

t₂.

10. The method of claim 8, wherein said chemical reaction comprises an analyte obtained from a bodily fluid.

11. The method of claim 10, wherein said observable is associated with concentration of said analyte in a reaction sample.

12. The method of claim 8, wherein said observable comprises an optically detectable species associated with said chemical reaction.

13. The method of claim 8, wherein said observable comprises an electrically detectable species associated with said chemical reaction.

14. The method of claim 8, wherein said measuring comprises:

(a) measuring a first set of values A₁, A₂, and A₃ for said observable during a first observation period; and

(b) measuring a second set of values A₁, A₂, and A₃ for said observable during a second observation period.

15. The method of claim 14, wherein said determining comprises:

(a) determining a first end point value from said first set of values;

(b) determining a second end point value from said second set of values; and

(c) determining a difference between said first and second end point values.

16. The method of claim 15, further comprising:

(a) measuring an nth set of values A₁, A₂, and A₃ for said observable during an nth observation period;

(b) determining an nth end point value from said nth set of values; and

(c) determining if said first, second and nth end point values are convergent.

17. A system for characterizing a reaction end point, comprising:

(a) stored programming capable of inputting at least three measurements, at three different time points, of a value associated with an observable indicative of progress of a chemical reaction; and

(c) stored programming capable of determining an end point value for said observable from said measurements.

18. The system of claim 17, wherein said stored programming is configured to determine said end point value according to the difference of an intermediate measured value, less a number equal approximately to the square of the difference between a later measured and an earlier measured value divided by a number equal approximately to an integer multiple of said later measured value less twice said intermediate measured value plus said initial measured value.

19. The system of claim 17, wherein said time points separated by equal intervals of time.

20. The system of claim 17, wherein said chemical reaction comprises an analyte obtained from a bodily fluid.

21. The system of claim 20, wherein said observable is associated with concentration of said analyte in a reaction sample.

22. The system of claim 17, wherein said observable comprises an optically detectable species associated with said chemical reaction.

23. The system of claim 17, wherein said observable comprises an electrically detectable species associated with said chemical reaction.

24. A system for characterizing a reaction end point, comprising:

(a) stored programming capable of inputting first, second and third values A₁, A₂, and A₃ measured at times t₁, t₂ and t₃ respectively, for an observable associated with a chemical reaction; and

(b) stored programming capable of determining an endpoint value A_∞

for said observable according to the relationship

$A_{\mathrm{\infty <br><br>}}\cong <br><br>A_2-\frac{{\left(A_3-A_1\right)}^2}{4<br><br>\left(A_3-2<br><br>\text{\hspace{1em}<br><br>}<br><br>A_2+A_1\right)}.$

25. The system of claim 24, wherein time interval t₂−

t₁ is equal to time interval t₃−

t₂.

26. The system of claim 24, wherein said chemical reaction comprises an analyte obtained from a bodily fluid.

27. The system of claim 26, wherein said observable is associated with concentration of said analyte in a reaction sample.

28. The system of claim 24, wherein said observable comprises an optically detectable species associated with said chemical reaction.

29. The system of claim 24, wherein said observable comprises an electrically detectable species associated with said chemical reaction.

30. The system of claim 24, further comprises:

(a) stored programming capable of inputting a first set of values A₁, A₂, and A₃ for said observable during a first observation period; and

(b) stored programming capable of inputting a second set of values A₁, A₂, and A₃ for said observable during a second observation period.

31. The system of claim 30, further comprises:

(a) stored programming capable of determining a first end point value from said first set of values;

(b) stored programming capable of determining a second end point value from said second set of values; and

(c) stored programming capable of determining a difference between said first and second end point values.

32. The system of claim 31, further comprises:

(a) stored programming capable of inputting an nth set of values A₁, A₂, and A₃ for said observable during an nth observation period;

(b) stored programming capable of inputting an nth end point value from said nth set of values; and

(c) stored programming capable of inputting if said first, second and nth end point values are convergent.