US4382122A
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Calcium assay
Assignee: SHERWOOD INDUSTRIES Inc A CORP OF DE
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Filing: 1981-10-14
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Granted: 1983-05-03
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Expires: 2001-10-14
Abstract
Abstract The stability of a reagent comprising an aqueous solution of a phenolsulphonephthalein dye is enhanced by the presence of a weak acid in the reagent.
Inventors
- 👤 Louis M. Mezei
- 👤 Laurence N. Jacobs
- 👤 Samuel C. Berry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:22
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22; G01N33/00; G01N33/48; G01N33/50; G01N33/84
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
58 words
In a reagent comprising an aqueous solution of a dye which comprises a phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, the improvement wherein said reagent includes a stabilizing amount of a weak acid.
Claim 2
Dependent Claim
58 words
In a reagent comprising an aqueous solution of a dye which comprises a phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, the improvement wherein said reagent includes a stabilizing amount of a weak acid.
Claim 3
Dependent Claim
27 words
The improvement of claim 1 wherein said weak acid is selected from the group consisting of propionic acid, acetic acid, benzoic acid, phthalic acid and formic acid.
Claim 4
Dependent Claim
11 words
The improvement of claim 2 wherein said dye is methylthymol blue.
Claim 5
Dependent Claim
71 words
In a reagent for determination and demonstration of calcium in a liquid sample, said reagent comprising an aqueous solution of methylthymol blue dye and an amount of 8-hydroxyquinoline sufficient to sequester magnesium present in said sample, the improvement wherein said reagent further includes a weak acid in an amount sufficient to maintain said 8-hydroxyquinoline in solution and to stabilize said methylthymol blue dye, said reagent being substantially free of strong acids.
Claim 6
Dependent Claim
71 words
In a reagent for determination and demonstration of calcium in a liquid sample, said reagent comprising an aqueous solution of methylthymol blue dye and an amount of 8-hydroxyquinoline sufficient to sequester magnesium present in said sample, the improvement wherein said reagent further includes a weak acid in an amount sufficient to maintain said 8-hydroxyquinoline in solution and to stabilize said methylthymol blue dye, said reagent being substantially free of strong acids.
Claim 7
Dependent Claim
27 words
The improvement of claim 4 wherein said weak acid is selected from the group consisting of propionic acid, acetic acid, benzoic acid, phthalic acid and formic acid.
Claim 8
Dependent Claim
30 words
The improvement of claim 5 wherein said weak acid is o-phthalic acid and is present in an amount such that the pH of said reagent is less than about 4.5.
Claim 9
Independent Claim
62 words
A method of stabilizing an aqueous solution of a dye which comprises phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, said method comprising the step of including a dye-stabilizing amount of a weak acid in said dye solution.
Claim 10
Independent Claim
62 words
A method of stabilizing an aqueous solution of a dye which comprises phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, said method comprising the step of including a dye-stabilizing amount of a weak acid in said dye solution.
Claim 11
Dependent Claim
27 words
The method of claim 7 wherein said weak acid is selected from the group consisting of propionic acid, acetic acid, benzoic acid, phthalic acid and formic acid.
Claim 12
Dependent Claim
11 words
The method of claim 8 wherein said dye is methylthymol blue.
Claim 13
Independent Claim
51 words
A method of stabilizing an aqueous solution of methylthymol blue dye and 8-hydroxyquinoline, said method comprising the step of including in said solution an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and to stabilize said methylthymol blue dye, said solution being substantially free of strong acids.
Claim 14
Independent Claim
51 words
A method of stabilizing an aqueous solution of methylthymol blue dye and 8-hydroxyquinoline, said method comprising the step of including in said solution an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and to stabilize said methylthymol blue dye, said solution being substantially free of strong acids.
Claim 15
Dependent Claim
27 words
The method of claim 10 wherein said weak acid is selected from the group consisting of propionic acid, acetic acid, benzoic acid, phthalic acid and formic acid.
Claim 16
Dependent Claim
32 words
The method of claim 10 wherein said weak acid is o-phthalic acid and said acid is present in an amount such that the pH of said solution is less than about 4.5.
Claim 17
Dependent Claim
52 words
A reagent comprising an aqueous solution of: (a) a dye comprising phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof; and (b) a dye-stabilizing amount of a weak acid.
Claim 18
Dependent Claim
52 words
A reagent comprising an aqueous solution of: (a) a dye comprising phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof; and (b) a dye-stabilizing amount of a weak acid.
Claim 19
Dependent Claim
27 words
The reagent of claim 13 wherein said weak acid is selected from the group consisting of propionic acid, acetic acid, benzoic acid, phthalic acid and formic acid.
Claim 20
Dependent Claim
11 words
The reagent of claim 14 wherein said dye is methylthymol blue.
Claim 21
Dependent Claim
39 words
A reagent comprising an aqueous solution of methylthymol blue dye, 8-hydroxyquinoline, and an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and stabilize said methylthymol blue dye, said solution being substantially free of strong acids.
Claim 22
Dependent Claim
39 words
A reagent comprising an aqueous solution of methylthymol blue dye, 8-hydroxyquinoline, and an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and stabilize said methylthymol blue dye, said solution being substantially free of strong acids.
Claim 23
Dependent Claim
27 words
The reagent of claim 16 wherein said weak acid is selected from the group consisting of propionic acid, acetic acid, benzoic acid, phthalic acid and formic acid.
Claim 24
Dependent Claim
30 words
The reagent of claim 17 wherein said weak acid is o-phthalic acid and is present in an amount such that the pH of said reagent is less than about 4.5.
Claim 25
Dependent Claim
16 words
A diagnostic kit comprising a prepackaged container of the reagent of claim 13 or claim 16.
Claim 26
Independent Claim
92 words
A method of determining calcium in a liquid sample, said method comprising the steps of: (a) mixing said sample with a reagent comprising an aqueous solution of a phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, and a dye stabilizing amount of a weak acid, to form a reaction mixture; (b) observing the color change of said reaction mixture; and (c) comparing said color change to calibration means.
Claim 27
Independent Claim
92 words
A method of determining calcium in a liquid sample, said method comprising the steps of: (a) mixing said sample with a reagent comprising an aqueous solution of a phenolsulphonephthalein dye which contains methylenenitrilo diacetic acid group substituents in the 6 and 6'-positions on the phenol rings and spectrum shifting, noncalcium binding substituents in the 2, 2' and 5, 5'-positions thereof, and a dye stabilizing amount of a weak acid, to form a reaction mixture; (b) observing the color change of said reaction mixture; and (c) comparing said color change to calibration means.
Claim 28
Dependent Claim
27 words
The method of claim 20 wherein said weak acid is selected from the group consisting of propionic acid, acetic acid, benzoic acid, phthalic acid and formic acid.
Claim 29
Dependent Claim
11 words
The method of claim 21 wherein said dye is methylthymol blue.
Claim 30
Independent Claim
82 words
A method of determining calcium in a liquid sample, said method comprising the steps of: (a) mixing said sample with a reagent comprising an aqueous solution of methylthymol blue dye, 8-hydroxyquinoline, and an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and stabilize said methylthymol blue dye to form a reaction mixture, said solution being substantially free of strong acids; (b) observing the color change of said reaction mixture; and, (c) comparing said color change to calibration means.
Claim 31
Independent Claim
82 words
A method of determining calcium in a liquid sample, said method comprising the steps of: (a) mixing said sample with a reagent comprising an aqueous solution of methylthymol blue dye, 8-hydroxyquinoline, and an amount of a weak acid sufficient to maintain said 8-hydroxyquinoline in solution and stabilize said methylthymol blue dye to form a reaction mixture, said solution being substantially free of strong acids; (b) observing the color change of said reaction mixture; and, (c) comparing said color change to calibration means.
Claim 32
Dependent Claim
27 words
The method of claim 23 wherein said weak acid is selected from the group consisting of propionic acid, acetic acid, benzoic acid, phthalic acid and formic acid.
Claim 33
Dependent Claim
30 words
The method of claim 24 wherein said weak acid is o-phthalic acid and is present in an amount such that the pH of said reagent is less than about 4.5.
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) | 1986-05-02 | 1986-11-01 | 1987-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-02 | 1990-11-01 | 1991-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-02 | 1994-11-01 | 1995-05-03 | $7700.00 | Window Closed / Lapsed |