US3798000A
Expired / Lapsed
US
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Agent and method for determination of calcium
Assignee: Merck Patent GmbH
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Filing: 1972-08-14
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Granted: 1974-03-19
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Expires: 1992-08-14
Abstract
Abstract An agent for the colorimetric determination of calcium, containing a color reagent, which forms complexes in the presence of calcium ions, and a buffer system which consists essentially of a mixture of amidosulfonic acid, disodium tetraborate and alkali carbonate.
Inventors
- 👤 R Helger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:12
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/50; G01N33/84; G01N2800/00; G01N2800/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
29 words
An agent in accordance with claim 1 wherein said color reagent and amidosulfonic acid are in tablet form and said alkali carbonate and disodium tetraborate are in solution form.
Claim 2
Dependent Claim
17 words
An agent in accordance with claim 2, wherein said color reagent comprises phthalein purple and 8-hydroxyquinoline sulfate.
Claim 3
Dependent Claim
36 words
An agent in accordance with claim 1 wherein said buffer system comprises in grams per liter of aqueous solution, 4 - 5 g. amidosulfonic acid, 0.5 - 0.8 g. disodium tetraborate, and 8-12 g. sodium carbonate.
Claim 4
Dependent Claim
17 words
An agent in accordance with claim 1 wherein said color reagent comprises phthalein purple and 8-hydroxyquinoline sulfate.
Claim 5
Independent Claim
66 words
A method for colorimetric determination of calcium ions in a test solution, comprising mixing said calcium ion-containing test solution with an agent solution comprising a color reagent which forms color complexes in the presence of calcium ions, and a buffer system consisting essentially of amidosulfonic acid, disodium tetraborate, and an alkali carbonate, and thereafter measuring the light absorption of the color complex formed in the solution.
Claim 6
Dependent Claim
35 words
A method in accordance with claim 6 wherein said color reagent and said amidosulfonic acid in tablet form are mixed with an aqueous solution of sodium tetraborate and sodium carbonate to form said agent solution.
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) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |