US4351899A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semi-quantitative assay of metabolic acids
Assignee: Individual
•
Filing: 1981-02-19
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Granted: 1982-09-28
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Expires: 2001-02-19
Abstract
Abstract A test indicator determines concentration, in a biological fluid, of a metabolic acid, such as beta-hydroxybutyrate or lactic acid. The indicator includes a test surface containing the dried residue resulting from impregnation of the surface with components including a tetrazolium salt, nicotinamide adenine dinucleotide (NAD), an electron carrier, and the enzyme that is a dehydrogenase for the specific metabolic acid being assayed. The indicator also includes a physically distinct provision for buffering the reaction. In accordance with the concentration of the metabolic acid being assayed, the indicator provides a predetermined color or intensity which can be observed either with the naked eye or with instrumentation such as a reflectance meter.
Inventors
- 👤 Oliver E. Owen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:43
CPC Classifications
C; C12; C12Q; C12Q1/00; C12Q1/26; C12Q1/32; Y; Y10; Y10S; Y10S435/00; Y10S435/805; Y10S435/81
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
105 words
A test indicator for determining the concentration of a metabolic acid selected from the group consisting of beta-hydroxybutyrate and lactic acid in a biological fluid, such indicator comprising: (a) a first absorbant test surface containing the dried residue resulting from impregnation of the surface with components including (i) a tetrazolium salt; (ii) nicotinamide adenine dinucleotide (NAD); (iii) an electron carrier; (iv) the enzyme that is a dehydrogenase for the metabolic acid; and (b) means, distinct from the first absorbant test surface, for buffering the biological fluid, wherein said recited components are present in amounts sufficient to react together to determine the concentration of said acid.
Claim 2
Dependent Claim
105 words
A test indicator for determining the concentration of a metabolic acid selected from the group consisting of beta-hydroxybutyrate and lactic acid in a biological fluid, such indicator comprising: (a) a first absorbant test surface containing the dried residue resulting from impregnation of the surface with components including (i) a tetrazolium salt; (ii) nicotinamide adenine dinucleotide (NAD); (iii) an electron carrier; (iv) the enzyme that is a dehydrogenase for the metabolic acid; and (b) means, distinct from the first absorbant test surface, for buffering the biological fluid, wherein said recited components are present in amounts sufficient to react together to determine the concentration of said acid.
Claim 3
Dependent Claim
41 words
A test indicator according to claim 1, wherein the means for buffering the biological fluid comprises a second absorbant test surface, proximate to the first test surface, containing the dried residue resulting from impregnation of the surface with a buffer solution.
Claim 4
Dependent Claim
20 words
A test indicator according to claim 2, wherein the metabolic acid is beta-hydroxybutyrate (BOHB), and the enzyme is BOHB dehydrogenase.
Claim 5
Dependent Claim
29 words
A test indicator according to claim 3, wherein the first test surface contains the dried residue resulting from impregnation of the surface with components also including potassium palladium tetrachloride.
Claim 6
Dependent Claim
15 words
A test indicator according to claim 4, wherein the electron carrier is 8-dimethylamino-2,3-benzophenoxazine (meldola blue).
Claim 7
Dependent Claim
39 words
A test indicator according to claim 5, wherein the first test surface contains the dried residue resulting from impregnation of the surface with components also including formazan solubilizer alkylphenoxypolyethoxyethanol, and wherein the tetrazolium salt is 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl-2H tetrazolium chloride (INT).
Claim 8
Dependent Claim
18 words
A test indicator according to claim 5, wherein the buffer solution is at a pH of approximately 8.8.
Claim 9
Dependent Claim
59 words
A test indicator according to claim 7, wherein the first test surface contains the dried residue resulting from impregnation of the surface with components having approximately the same relative proportions as the following concentrations per unit volume: INT, 8.9 mM NAD, 21 mM Meldola blue, 0.25 mM BOHB dehydrogenase, 60 I.U./ml. potassium palladium tetrachloride, 0.10 mM alkylphenoxypolyethoxyethanol, 1% v/v
Claim 10
Dependent Claim
40 words
A test indicator according to claim 7, wherein the buffer solution includes (a) glycine buffered with sodium hydroxide at a pH of approximately 8.8 and (b) potassium dihydrogen phosphate buffered with potassium dihydrogen phosphate at a pH of approximately 8.8.
Claim 11
Dependent Claim
20 words
A test indicator according to claim 2, wherein the metabolic acid is lactic acid and the enzyme is lactic dehydrogenase.
Claim 12
Dependent Claim
29 words
A test indicator according to claim 10, wherein the first test surface contains the dried residue resulting from impregnation of the surface with components also including potassium palladium tetrachloride.
Claim 13
Dependent Claim
15 words
A test indicator according to claim 11, wherein the electron carrier is 8-dimethylamino-2,3-benzophenoxazine (meldola blue).
Claim 14
Dependent Claim
39 words
A test indicator according to claim 13, wherein the first test surface contains the dried residue resulting from impregnation of the surface with components also including formazan solubilizer alkylphenoxypolyethoxyethanol, and wherein the tetrazolium salt is 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl-2H tetrazolium chloride (INT).
Claim 15
Dependent Claim
18 words
A test indicator according to claim 13, wherein the buffer solution is at a pH of approximately 9.5.
Claim 16
Dependent Claim
60 words
A test indicator according to claim 14, wherein the first test surface contains the dried residue resulting from impregnation of the surface with components having approximately the same relative proportions as the following concentrations per unit volume: INT, 8.9 mM NAD, 21 mM Melodola blue, 0.25 mM lactic dehydrogenase, 2750 I.U./ml potassium palladium tetrachloride, 0.10 mM alkyl phenoxypolyethoxyethanol, 1% v/v
Claim 17
Dependent Claim
23 words
A test indicator according to claim 15, wherein the buffer solution includes glycine buffered with sodium hydroxide at a pH of approximately 9.5.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-27 | 1986-03-29 | 1986-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-27 | 1990-03-29 | 1990-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-27 | 1994-03-29 | 1994-09-28 | $7700.00 | Window Closed / Lapsed |