Optical end-point type analytical method

• US 5,047,351 A
• Filed: 05/10/1989
• Issued: 09/10/1991
• Est. Priority Date: 09/01/1986
• Status: Expired due to Term

• Current Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Murabayashi, Kenji, Iwata, Yuzo, Hirai, Kikuo, Makiuchi, Hajime
• Primary Examiner(s): Hill, Jr., Robert J.
• Application Number:
  US07/351,315
• Time in Patent Office: 853 Days
• Field of Search: 436/34, 436/164, 436/169, 436/170, 436/172, 422/56, 364/497
• US Class Current: 436/169
• 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 2021/174 either absorption-reflection or emission-fluorescence
• CPC Class Codes: G01N 21/272 for following a reaction, e.g. for determining photometrically a reaction rate (photometric cinetic analysis)
• CPC Class Codes: G01N 21/78 producing a change of colour
• CPC Class Codes: G01N 33/521 Single-layer analytical elements

Abstract

A method for shortening the analysis time, without adversely affecting the accuracy in the colorimetric analysis of an analyte. The method including the steps of:

(a) Measuring the optical density for two or more times at suitable time intervals after the beginning of reaction to follow the variation of optical density,

(b) Judging based upon the optical density obtained at the earlier measurement whether the reaction is to be further continued or not,

(c) When it is judged that the continuation of the reaction is not necessary in terms of analytical accuracy, selecting the calibration curve corresponding to the reaction time,

(d) While, when it is judged that the continuation of the reaction is necessary, further continuing the reaction, and

(e) Repeating steps (b) and (d) until the judgement that the continuation of the reaction is not necessary is obtained.

Claims

1. A method of analyzing the concentration of an analyte using the end-point method and plural predetermined calibration curves showing the variation of the optical density or emission intensity with analyte concentrations at various predetermined time intervals by observing the variation in optical density or emission intensity of a sample occurring due to the reaction of the analyte, which comprises:

(a) measuring the optical density or emission intensity due to the reaction of the analyte at least once at a predetermined time interval after the beginning of the reaction;

(b) if the optical density or emission intensity obtained at the first measurement is smaller than a predetermined critical value (TH₁), selecting a predetermined calibration curve showing the variation of the optical density or emission intensity with analyte concentrations at various predetermined time intervals for a reaction time corresponding to said first measurement, and discontinuing the measurement,

(c) if the optical density or emission intensity obtained at the first measurement is not smaller than a predetermined critical value (TH₁), continuing the reaction further until an optical density or emission intensity smaller than TH₁ wherein ₁ is at least 2 and TH₁ is greater than TH_1-1 for each time interval T₁ is obtained, then selecting a predetermined calibration curve showing the variation of optical density or emission intensity with analyte concentration at the predetermined time interval for a reaction time corresponding to the measurement where the optical density or emission intensity smaller than TH₁ is obtained for the first time, and discontinuing the measurement, and

(d) determining the amount of the analyte using said selected calibration curve.

2. The method of claim 1 wherein the analysis is carried out using an integral dry-type analytical element.