US4618587A
Expired / Lapsed
US
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Method for the quantitative determination of calcium in biological fluids through direct potentiometry
Assignee: Fisher Scientific Co LLC
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Filing: 1985-02-21
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Granted: 1986-10-21
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Expires: 2005-02-21
Abstract
Abstract A method is disclosed for determining calcium ion content of serum which comprises calibrating a potentiometric analytical system with calcium standards having a solution containing both TRIS and BisTRIS at a pH of 7.5. The serum sample is diluted with a silicone oil/water emulsion which may further contain a protein complexing agent such as iron, zinc, cadmium, nickel or copper. Measurement is then carried out on the diluted serum sample.
Inventors
- 👤 Pietro Premoli
- 👤 Angelo Manzoni
- 👤 Claudio Calzi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:27
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/50; G01N33/84; H; H02; H02K; H02K19/00; H02K19/16; H02K19/34; H02K21/00; H02K21/48; Y; Y10; Y10T; Y10T436/00; Y10T436/10; Y10T436/106664
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
109 words
In a method for the determination of calcium ion content of serum using a potentiometric system the improvement comprising the steps of calibrating the potentiometric system with a first calibrating solution containing about 0.001 molar calcium and a second calibrating solution containing about 0.003 molar calcium, the first and second calibrating solutions also containing about 0.1 molar tris(hydroxymethyl)aminomethane or derivatives thereof having a pH value of about 7.5 at about 25° C. and from about 300 to about 400 milligrams per deciliter of 2.2 Bis-(hydroxymethyl)-2,2',2"-nitrilotriethanol, and diluting a serum sample with a dilution solution containing 0.1 molar tris(hydroxymethyl)aminoethane having a pH value of about 7.5 at about 25° C.
Claim 2
Dependent Claim
109 words
In a method for the determination of calcium ion content of serum using a potentiometric system the improvement comprising the steps of calibrating the potentiometric system with a first calibrating solution containing about 0.001 molar calcium and a second calibrating solution containing about 0.003 molar calcium, the first and second calibrating solutions also containing about 0.1 molar tris(hydroxymethyl)aminomethane or derivatives thereof having a pH value of about 7.5 at about 25° C. and from about 300 to about 400 milligrams per deciliter of 2.2 Bis-(hydroxymethyl)-2,2',2"-nitrilotriethanol, and diluting a serum sample with a dilution solution containing 0.1 molar tris(hydroxymethyl)aminoethane having a pH value of about 7.5 at about 25° C.
Claim 3
Dependent Claim
29 words
The method of claim 1 wherein the dilution solution also contains 1 part emulsion per 9 to 19 parts dilution solution wherein the emulsion is a silicone oil/water emulsion.
Claim 4
Dependent Claim
26 words
The method of claim 1 wherein the dilution solution also contains a complexing agent selected from the group consisting of iron, zinc, cadmium, nickel and copper.
Claim 5
Dependent Claim
21 words
The method of claim 3 wherein the complexing agent is zinc and is present between about 0.05 to about 0.4 mmols/l.
Claim 6
Dependent Claim
19 words
The method of claim 4 containing Zn++ as ZnCl 2 in concentration ranging from about 0.3 mmols per liter.
Claim 7
Dependent Claim
32 words
The method of claim 1 wherein the dilution solution contains a silicone oil/water emulsion prepared by homogenizing said oil from 10 to 20% with non-ionic surfactant from 1 to 5% in water.
Claim 8
Dependent Claim
29 words
The method of claim 1 where the calibrating solutions and serum sample are diluted with the dilution solution wherein the dilution ratio ranges between about 1:10 to about 1:50.
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) | 1989-10-20 | 1990-04-21 | 1990-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-20 | 1994-04-21 | 1994-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-20 | 1998-04-21 | 1998-10-21 | $7700.00 | Window Closed / Lapsed |