Method and apparatus for analysis of constituent carried in fibrous medium

• US 4,059,405 A
• Filed: 08/19/1976
• Issued: 11/22/1977
• Est. Priority Date: 04/11/1972
• Status: Expired due to Term

• Current Assignee: International Equipment Company (Thermo Fisher Scientific Incorporated)
• Original Assignee: Damon Corporation (Thor Industries Incorporated)
• Inventors: Lim, Franklin, Sodickson, Lester A.
• Primary Examiner(s): Reese, Robert M.
• Application Number:
  US05/715,855
• Time in Patent Office: 460 Days
• Field of Search: 23/230 R, 23/230 B, 23/232 R, 23/253 R, 162/158, 162/168, 356/209
• US Class Current: 436/44
• 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 33/52 Use of compounds or compositions for colorimetric, spectrophotometric or fluorometric investigation, e.g. use of reagent paper and including single- and multilayer analytical elements immunological elements G01N33/54386; involving labelled immunochemicals G01N33/58; for haemoglobin or occult blood G01N33/72
• CPC Class Codes: Y10T 436/110833 Utilizing a moving indicator strip or tape
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

An optically-thin preparation of a sample solution and chemical reagents produces a constituent-manifesting reaction product that can be measured in linear relation to the concentration of the constituent of interest. A fibrous sheet contains the sample and the reagents for both the reaction and the measurement. The same site on the fibrous sheet which bears the reacting materials serves as a blank to produce a reference signal for the measurement.

Claims

1. In the constituents analysis of sample material on a porous medium by reaction in a liquid state with reactants to produce a constituent-manifesting reaction product, the improvement comprising the steps of

A. producing said reaction product at said analysis site with only an optically-thin concentration,

B. illuminating said analysis site with incident electromagnetic radiation,

C. sensing, from a field of view coincident with said analysis site, electromagnetic radiation that is resultant from said incident radiation and responsive to both the background response of said medium to said illumination and the concentration of said reaction product, and

D. producing a sample-measuring signal in response to a differential function of said product-responsive sensed radiation and radiation resultant from incident radiation on said field of view and responsive to said background response of said medium at said analysis site and to said sample material and said reagents prior to said product-producing reaction.

2. In the constituent analysis of sample material on a porous medium by reaction with at least one reagent to produce a constituent-manifesting reaction product, the improvement comprising the steps of

A. distributing said sample material and said reagent in liquid state over a selected analysis site of said medium,

B. producing said reaction product at said analysis site with only an optically-thin concentration,

C. illuminating said analysis site with incident electromagnetic radiation,

D. sensing, from a field of view within said analysis site, electromagnetic radiation that is resultant from said incident radiation and responsive to the concentration of said reaction product, and

E. measuring the rate of change of said radiation sensed during the production of said reaction product.

3. In a method as defined in claim 2, the further improvement in which said measuring step measures the rate of change of said radiation from a time after the cessation of spreading of liquids in said medium.

4. In a method as defined in claim 2, the further improvement in that said radiation is sensed substantially continuously during production of said reaction product, said distributing step includes balancing the amounts of said sample material and said reagents at said analysis site to produce a substantially uniform rate of reaction, and the further step of timing said measurement of rate of change to coincide with at least a portion of the duration of said uniform rate of reaction.

5. In the constituent analysis of sample material on a porous medium by reaction with at least one reagent to produce a constituent-manifesting reaction product, the improvement comprising the steps of

A. distributing said sample material and said reagent in liquid state with substantially repeatable spatial distributions of concentration over a selected analysis site of said medium.

B. producing said reaction product at said analysis site with only an optically-thin concentration,

C. illuminating said analysis site with incident electromagnetic radiation,

D. sensing, from a field of view within said analysis site, electromagnetic radiation that is resultant from said incident radiation and responsive to the concentration of said reaction product, and

E. producing a measure of the constituent in response to radiation sensed from the same area within said site at at least two different times between which said reaction produces said reaction product.

6. In a method as defined in claim 5, the further improvement in that said step of producing said measure responds to a difference function of the radiation sensed at said different times.

7. In a method as defined in claim 5, the further improvement in which said sensing step comprises sensing fluorescence from said reaction product

8. In a method as defined in claim 5, the further improvement in which said medium has an unbounded test site.

9. In a method as defined in claim 5, the further improvement in that said distributing step distributes said sample material and said reagents in a concentration that does not saturate said medium at said analysis site.

10. In a method as defined in claim 5, the further step of maintaining the wetness of said reactants substantially the same at the times radiation is sensed for measurement.

11. In a method as defined in claim 5, the further step of maintaining a repeatable state of compression on said medium at said analysis site at the times radiation is sensed for measurement.

12. In a method as defined in claim 5, the further step of forming said porous medium with substantially non-wicking fibers at said analysis site.

13. In a method as defined in claim 5, the further steps of maintaining repeatable coupling of said incident radiation to said analysis site, and maintaining repeatable coupling of said resultant radiation from said site, at the times radiation is sensed for measurement.

14. In the constituent analysis of sample material on a porous medium by reaction with at least one reagent to produce a constituent-manifesting reaction product, the improvement comprising the steps of

A. distributing said sample material and said reagent in liquid state with substantially repeatable spatial distributions of concentration over a selected analysis site of said medium, with at least one reactant selected from said sample material and one said reagent being provided at said site with a nonuniform spatial distribution of concentration,

B. producing said reaction product at said analysis site with only an optically-thin concentration,

C. illuminating said analysis site with incident electromagnetic radiation, and

D. sensing, from a field of view within said analysis site, electromagnetic radiation that is resultant from said incident radiation and responsive to the concentration of said reaction product.

15. In a method as defined in claim 14, the further step of producing a measure of the concentration of a constituent in said sample in response to the integral of said sensed radiation over the area of at least a selected region of said test site.

16. A method of measuring the amount of a constituent of a soluble material sample comprising the steps of

A. forming a repeatable concentration distribution over a test site of a porous support member of each chemical reactant that produces, upon chemical reaction with said sample, a reaction product identifying the concentration of said constituent, with at least one reagent distribution being nonuniform,

B. forming a repeatable concentration distribution over said test site of said sample with a sufficiently low concentration to produce an optically-thin distribution of reaction product and allowing said sample to react, in liquid solution, with said reagents at said test site to produce said reaction product,

C. sensing electromagnetic radiation emitted from said test site in response to incident energy and to the concentration of said reaction product thereat,

D. integrating said sensed radiation emitted from at least a selected region of said test site, and

E. producing an output measure in response to the change in said integral of sensed radiation resultant from said production of said reaction product.

17. A method as defined in claim 16 in which said distribution-forming step comprises applying at least some of said reagents to said test site in sequential order according to the molecular size of an active constituent of each reagent, starting with the reagent having the largest molecular constituent.

18. In chemical spot-test analysis employing a measured parameter responsive to concentration of a reaction-produced material at a test spot on a porous medium subsequent to deposition of liquid to the test spot, the improvement comprising the step of measuring the change in said parameter over a time interval during which said reaction produces said material in such small amount that the optical absorbance thereof at the wavelength of measurement changes by less than 0.2 throughout the monitored area of said test spot.

19. In chemical spot-test analysis as defined in claim 18, the further improvement comprising the step of maintaining the reaction-producing reactants at said monitored area of said test spot in a liquid condition of uniform wetness during said time interval.

20. In chemical spot-test analysis according to claim 19, the further improvement comprising the step of maintaining the state of compression of said medium, at least at said monitored area and contiguously therabout, uniform during said selected time interval.

21. In apparatus for measuring a selected product of reactants in liquid solution at test site on a porous medium and having means for subjecting said site to oscillating electromagnetic energy and for sensing energy which is responsive to said oscillating energy and to the presence of said selected reaction product, the improvement comprising

A. measuring means for producing a measure of said sensed energy which is responsive to an optically-thin change in the concentration of said product at a single region of said site, and

B. means for providing repeatable coupling of energy between said means for subjecting and said means for sensing, by way of said test site of said medium, at at least two times at which energy is sensed for measurement and between which said reactants produce said reaction product.

22. In apparatus as defined in claim 21, the further improvement in which said means for providing includes means for maintaining the wetness of said reactants at said test site substantially the same at said times of sensing energy for measurement.

23. In apparatus as defined in claim 21, the further improvement in which said means for maintaining includes means for sealing said test site of said medium to diminish evaporation of liquid therefrom.

24. In apparatus as defined in claim 21, the further improvement in which said means for providing includes means for maintaining said medium, at least at said test site, under a repeatable state of compression at said times of sensing energy for measurement.

25. In apparatus as defined in claim 21, the further improvement in which said measuring means includes

A. a means for sensing said energy from said single region at two different times between which said reactants produce said selected product, and

B. means for producing said measure in response to a difference function of the energy sensed at said different times.

26. In apparatus for measuring a selected reaction product of reactants at a test site on a sheet-like porous medium and having means for subjecting said site to oscillating electromagnetic energy and for sensing a selected parameter of energy which is responsive to said oscillating energy and to the presence of said selected reaction product, the improvement comprising

A. support means for receiving said medium disposed with said test site within the field of view of said subjecting and sensing means, and for exposing said site for the receipt thereat of at least one reactant in liquid state for the production of said reaction product, and

B. measuring means for producing a measure of said sensed energy responsive to a change, at a single monitored area of said site, in the concentration of said product which produces a change in the optical absorbance of said medium at the wavelength of measurement of less than 0.2 throughout the monitored area of said test spot.

27. In apparatus as defined in claim 26, the further improvement comprising means for maintaining the reactants at said test site in a liquid condition with uniform wetness during the production of said measured change in the concentration of said reaction product.

28. In apparatus as defined in claim 26, the further improvement comprising means for maintaining said test site of said medium at a repeatable location relative to said means for subjecting and said means for sensing, at least at times of sensing energy for said measurement.

29. In a photometric instrument for illuminating a reactant-bearing test site with incident electromagnetic energy and for measuring resultant electromagnetic energy emitted from said site in response to said incident energy with a parameter responsive to a selected reaction product of said reactants, when in liquid state, the improvement comprising

A. first and second housing membersarranged to receive between them a sheetlike carrier of said site with said first housing member facing a first side of said carrier and said second housing member facing a second opposite side of said carrier, and with said incident energy illuminating one side of said site and said resultant energy being sensed at at least one side of said site,

one housing member being arranged for contiguous contact with both said carrier and said site,the other housing member being arranged for contact with the other side of said carrier and being normally spaced from the other side of said site,

so that said contact of said housing members with said carrier sheet locates said carrier sheet relative to the path of said illuminated and resultant energy, and said contiguous abutment of one housing member with said site locates said site relative thereto, and

B. means for sealing said test site at least during the sensing of resultant energy for measurement to diminish evaporation of liquid reactant therefrom.

30. In a photometric instrument according to claim 29, the further improvement comprising connection means joining said first and second housing means together for allowing said housing members to move apart to receive the sheet-like carrier of said site between them, and to move together into said contact with said carrier.

31. In chemical spot test analysis employing a measured parameter responsive to concentration of a reaction-produced material at a test spot on a fibrous medium, the improvement comprising the step of exposing at least said test spot of said fibrous medium, prior to the introduction of reaction-producing reagents to said test site, to an aqueous solution of a high molecular weight, crystalline, ethylene oxide polymer, said exposure being sufficient, after drying of said polymer solution, to diminish the absorption of liquid by the fibers of said medium.

32. In chemical spot test analysis as defined in claim 31, the further improvement comprising the step of drying said polymer solution on said fibrous medium subsequent to said exposing step and prior to introducing reaction-producing reactants to said test site.

33. In apparatus for measuring a selected product of chemical reactants at a test site on a fibrous medium and having means for subjecting said site to oscillating electromagnetic energy and for sensing a selected parameter of energy which is responsive to said oscillating energy and to the presence of said selected reaction product, the improvement comprising a substantially uniform fibrous structure in said fibrous medium within and contiguously beyond said reaction site, said structure consisting essentially of non-wicking fibrous material, and being characterized by the substantial termination of spreading therein of said reactants in liquid solution prior to the completion of said sensing of product-responsive energy.

34. In apparatus as defined in claim 33, the further improvement.

A. comprising measuring means for sensing product-responsive energy for a selected interval during which said reactants produce said selected product at a substantially linear rate, and

B. said uniform fibrous structure is further characterized by the substantial termination of spreading therein of said reactants in liquid solution significantly prior to the termination of said selected measuring interval.

35. In apparatus for measuring a selected product of chemical reactants at a test site on a fibrous medium and having means for subjecting said site to oscillating electromagnetic energy and for sensing a selected parameter of energy which is responsive to said oscillating energy and to the presence of said selected reaction product, the improvement wherein said fibrous medium consists essentially of paper-making fibers which are characterized by minimal absorption of liquid and are produced by treatment with a relatively high molecular weight polymer.

36. In apparatus for measuring a selected product of chemical reactants at a test site on a fibrous medium and having means for subjecting said site to oscillating electromagnetic energy and for sensing a selected parameter of energy which is responsive to said oscillating energy and to the presence of said selected reaction product, the improvement wherein said fibrous medium consists essentially of paper-making fibers which have been exposed to an aqueous solution of a high molecular weight, crystalline, ethylene oxide polymer and dried prior to the introduction thereto of said chemical reactants.