US3934977A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reagent and method for determining total calcium in body fluids
Assignee: American Hospital Supply Corp
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Filing: 1974-08-09
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Granted: 1976-01-27
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Expires: 1994-08-09
Abstract
Abstract A colorimetric determination of total calcium in serum and other body fluids comprising the steps of mixing the sample of body fluid with a liquid reagent consisting of 2,7-bis-(4 chloro-2-phosphonobenzeneazo)-1,8-dihydroxynapthalene-3,6-disulfonic acid, commonly known as chlorophosphonazo III, in a buffer system at pH 5.0 to 5.5, and thereafter spectrophotometrically measuring the level of color development. Potassium hydrogen phthalate is disclosed as a component of the buffer system.
Inventors
- 👤 Kenneth E. Cleaver
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 05:21
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/50; G01N33/84
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
79 words
A method for the rapid determination of total calcium in protein-containing body fluids, comprising the steps of mixing a sample of body fluid with a color reagent consisting essentially of an aqueous solution of chlorophosphonazo III buffered to a pH within the range of 5.0 to 5.5 by a buffer comprising potassium hydrogen phthalate, and thereafter optically comparing the color development of the sample-reagent mixture with that of the same reagent mixed with a standard of known calcium concentration.
Claim 2
Independent Claim
79 words
A method for the rapid determination of total calcium in protein-containing body fluids, comprising the steps of mixing a sample of body fluid with a color reagent consisting essentially of an aqueous solution of chlorophosphonazo III buffered to a pH within the range of 5.0 to 5.5 by a buffer comprising potassium hydrogen phthalate, and thereafter optically comparing the color development of the sample-reagent mixture with that of the same reagent mixed with a standard of known calcium concentration.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein the pH of said color reagent falls within the range of 5.35 to 5.45.
Claim 4
Dependent Claim
16 words
The method of claim 1 in which the pH of said color reagent is about 5.4.
Claim 5
Dependent Claim
43 words
A reagent for rapidly determining total calcium in a protein-containing body fluid, comprising an aqueous solution of chlorophosphonazo III buffered to a pH within the range of 5.0 to 5.5, said reagent including potassium acid phthalate as part of the buffer system thereof.
Claim 6
Dependent Claim
43 words
A reagent for rapidly determining total calcium in a protein-containing body fluid, comprising an aqueous solution of chlorophosphonazo III buffered to a pH within the range of 5.0 to 5.5, said reagent including potassium acid phthalate as part of the buffer system thereof.
Claim 7
Dependent Claim
14 words
The reagent of claim 4 in which the buffer system also includes potassium hydroxide.
Claim 8
Dependent Claim
17 words
The reagent of claim 4 in which said pH is within a range of 5.35 to 5.45.
Claim 9
Dependent Claim
12 words
The reagent of claim 4 in which said pH is about 5.4.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-26 | 1979-07-28 | 1980-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-26 | 1983-07-28 | 1984-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-26 | 1987-07-28 | 1988-01-27 | $7700.00 | Window Closed / Lapsed |