US4152116A
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Composition and method for the determination of ascorbic acid
Assignee: Roche Diagnostics GmbH
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Filing: 1978-06-28
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Granted: 1979-05-01
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Expires: 1998-06-28
Abstract
Abstract Ascorbic acid or dehydroascorbic acid is determined by reaction with a tetrazolium salt selected from 3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyl-tetrazolium bromide, nitrotetrazolium blue, tetrazolium blue chloride and distyryl-nitro blue tetrazolium chloride, in the presence of phenazine methosulphate and a detergent, at a weakly acidic pH value, and evaluating the coloration obtained as a measure of the initial acid content. The method is particularly efficacious in substantially eliminating disturbance of the reaction by foreign substances.
Inventors
- 👤 Ulfert Deneke
- 👤 Gerhard Michal
- 👤 Klaus Beauchamp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:19
CPC Classifications
C; C12; C12Q; C12Q1/00; C12Q1/26; G; G01; G01N; G01N33/00; G01N33/02; G01N33/025; G01N33/14; Y; Y10; Y10T; Y10T436/00; Y10T436/14; Y10T436/142222
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
71 words
Method for the determination of ascorbic acid or of dehydroascorbic acid, which method comprises reacting a sample solution containing such acid with a tetrazolium salt selected from the group consisting of 3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyl-tetrazolium bromide, nitrotetrazolium blue, tetrazolium blue chloride and distyryl-nitro blue tetrazolium chloride, in the presence of phenazine methosulphate and a detergent, at a weakly acidic pH value, and evaluating the coloration obtained as a measure of the initial acid content.
Claim 2
Dependent Claim
71 words
Method for the determination of ascorbic acid or of dehydroascorbic acid, which method comprises reacting a sample solution containing such acid with a tetrazolium salt selected from the group consisting of 3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyl-tetrazolium bromide, nitrotetrazolium blue, tetrazolium blue chloride and distyryl-nitro blue tetrazolium chloride, in the presence of phenazine methosulphate and a detergent, at a weakly acidic pH value, and evaluating the coloration obtained as a measure of the initial acid content.
Claim 3
Dependent Claim
16 words
Method as claimed in claim 1 wherein the pH value is adjusted with a phosphate/citrate buffer.
Claim 4
Dependent Claim
14 words
Method as claimed in claim 1 wherein said detergent is an alkylaryl-polyethylene glycol ester.
Claim 5
Dependent Claim
14 words
Method as claimed in claim 1 wherein the pH is from 4.0 to 6.
Claim 6
Dependent Claim
13 words
Method as claimed in claim 1 wherein a sequestering agent is also present.
Claim 7
Dependent Claim
23 words
Method as claimed in claim 1 wherein the said measure of the initial acid content is taken by way of an extinction reading.
Claim 8
Dependent Claim
38 words
Method as claimed in claim 6 wherein said extinction reading is adjusted by subtracting therefrom a blank extinction value determined for a blank batch of sample solution with ascorbate oxidase added thereto, after completion of the oxidation reaction.
Claim 9
Dependent Claim
56 words
Method as claimed in claim 1 wherein dehydroascorbic acid is determined, which method comprises adding an excess of sulfhydryl compound to the sample solution at a pH from 7 to 8, permitting an oxidation reaction to proceed, adjusting the pH value of the reaction mixture to 4.8 to 5.3, and then determining the ascorbic acid content.
Claim 10
Dependent Claim
12 words
Method as claimed in claim 8 wherein said sulfhydryl compound is homocysteine.
Claim 11
Dependent Claim
46 words
Reagent for the determination of ascorbic acid and of dehydroascorbic acid, comprising a tetrazolium salt selected from the group consisting of 3-(4,5-dimethyl-thiazolyl-2)-2, 5-diphenyl-tetrazolium bromide, nitrotetrazolium blue, tetrazolium blue chloride or distyrylnitro blue tetrazolium chloride, together with phenazine methosulfate, a detergent, and a weakly acidic buffer substance.
Claim 12
Dependent Claim
46 words
Reagent for the determination of ascorbic acid and of dehydroascorbic acid, comprising a tetrazolium salt selected from the group consisting of 3-(4,5-dimethyl-thiazolyl-2)-2, 5-diphenyl-tetrazolium bromide, nitrotetrazolium blue, tetrazolium blue chloride or distyrylnitro blue tetrazolium chloride, together with phenazine methosulfate, a detergent, and a weakly acidic buffer substance.
Claim 13
Dependent Claim
11 words
Reagent as claimed in claim 11 also containing a sulfhydryl compound.
Claim 14
Dependent Claim
10 words
Reagent as claimed in claim 10 also containing ascorbate oxidase.
Claim 15
Dependent Claim
11 words
Reagent as claimed in claim 10 also containing a sequestering agent.
Claim 16
Dependent Claim
18 words
Reagent as claimed in claim 10 wherein said buffer substance is phosphate/citrate buffer of pH 4.0 to 6.
Claim 17
Dependent Claim
13 words
Reagent as claimed in claim 10 containing 3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyltetrazolium bromide as the tetrazolium salt.
Claim 18
Dependent Claim
15 words
Reagent as claimed in claim 10 wherein said detergent is an alkylaryl polyethylene glycol ester.
Claim 19
Dependent Claim
59 words
Reagent as claimed in claim 10 comprising: 0.01 to 1 mMol of the tetrazolium salt per liter, 0.01 to 1 mMol phenazine methosulphate per liter, 0.1 to 1 mol buffer substance per liter, 0.1 to 2 wt.% detergent, 1 to 50 U per ml. ascorbate oxidase, 0.1 to 10 mMol sequestering agent per liter, based on final test solution.
Claim 20
Dependent Claim
65 words
Reagent as claimed in claim 10 essentially consisting of: 0.05 to 0.15 mMol 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide per liter, 0.05 to 0.15 mMol phenazine methosulphate per liter, 0.5 to 1.5% v/v octylphenyl-polyethylene oxide ether, 0.5 to 5 mMol ethylenediamine-tetraacetic acid per liter, 0.1 to 0.4 mMol phosphate/citrate buffer, pH 4.8 to 5.3 per liter, 1 to 10 U per ml. ascorbate oxidase, based on final test solution.
Claim 21
Dependent Claim
62 words
Reagent test strip for the determination of ascorbic acid and/or dehydroascorbic acid comprising, impregnated onto a carrier material, a tetrazolium salt selected from the group consisting of 3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyl-tetrazolium bromide, nitrotetrazolium blue, tetrazolium blue chloride or distyrylnitro blue tetrazolium chloride, together with phenazine methosulphate, a detergent, a weakly acidic buffer substance and optionally a sulphhydryl compound and/or ascorbate oxidase and/or a sequestering agent.
Claim 22
Dependent Claim
62 words
Reagent test strip for the determination of ascorbic acid and/or dehydroascorbic acid comprising, impregnated onto a carrier material, a tetrazolium salt selected from the group consisting of 3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyl-tetrazolium bromide, nitrotetrazolium blue, tetrazolium blue chloride or distyrylnitro blue tetrazolium chloride, together with phenazine methosulphate, a detergent, a weakly acidic buffer substance and optionally a sulphhydryl compound and/or ascorbate oxidase and/or a sequestering agent.
Claim 23
Dependent Claim
21 words
Reagent as claimed in claim 19 also containing at least one of a sulphhydryl compound, ascorbate oxidase and a sequestering agent.
References Cited (Backward Citations)
US3771964A
Cited
US4056485A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-04-30 | 1982-10-30 | 1983-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-30 | 1986-10-30 | 1987-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-30 | 1990-10-30 | 1991-05-01 | $7700.00 | Window Closed / Lapsed |