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US3853473A
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Reagent and method for urea determination
Assignee: Medico Electronic Inc
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Filing: 1972-08-30
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Granted: 1974-12-10
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Expires: 1992-08-30
Abstract
Abstract A colorimetric reagent and method for the determination of blood urea. The method involves the addition of a small amount of serum to a reagent containing p-dimethylaminobenzaldehyde in acidic dimethylformamide and immediately measuring the increase in absorbance at 450 nm. The increase in absorbance is directly proportional to the urea concentration. The response is sensitive, requires no heating, and is linear up to 125 mg percent of urea nitrogen.
Inventors
- 👤 L Morin
- 👤 J Prox
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 07:46
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/50; G01N33/62; Y; Y10; Y10T; Y10T436/00; Y10T436/17; Y10T436/171538
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
55 words
A REAGENT FOR THE DETERMINATION OF UREA IN BIOLOGICAL FLUIDS COMPRISED OF AN ACIDIFIED SOLUTION OF PDIMETHYLAMINOBENALHYDE IN A DIPOLAR APROTIC SOLVENT, SAID P-DIMETHYLAMINOBENZALDEHYDE BEING PRESENT AT A LEVEL BETWEEN 0.1 TO 10 GRAM PERCENT, AND THE SOLUTION BEING ACIDIFIED BY AN ACIDIFYING AGENT WHICH IS PRESENT IN AN AMOUNT BETWEEN 1 TO 30 PERCENT.
Claim 2
Dependent Claim
55 words
A REAGENT FOR THE DETERMINATION OF UREA IN BIOLOGICAL FLUIDS COMPRISED OF AN ACIDIFIED SOLUTION OF PDIMETHYLAMINOBENALHYDE IN A DIPOLAR APROTIC SOLVENT, SAID P-DIMETHYLAMINOBENZALDEHYDE BEING PRESENT AT A LEVEL BETWEEN 0.1 TO 10 GRAM PERCENT, AND THE SOLUTION BEING ACIDIFIED BY AN ACIDIFYING AGENT WHICH IS PRESENT IN AN AMOUNT BETWEEN 1 TO 30 PERCENT.
Claim 3
Dependent Claim
12 words
A reagent according to claim 1 wherein said dipolar solvent is dimethylformamide.
Claim 4
Dependent Claim
14 words
A reagent according to claim 1 wherein said solution is acidified with an acid.
Claim 5
Dependent Claim
12 words
A reagent according to claim 3 wherein the acid is sulfuric acid.
Claim 6
Dependent Claim
13 words
A reagent according to claim 4 wherein said dipolar aprotic solvent is dimethylformamide.
Claim 7
Dependent Claim
50 words
A method for determining urea in biological fluids which comprises mixing a small sample of biological fluid with the reagent of claim 1, the ratio of the biological fluid to the reagent being between 1:100 and 1:25, and determining the concentration of the urea by means of measuring the absorbance.
Claim 8
Dependent Claim
19 words
A method according to claim 6 wherein the absorbance is measured at a point between 400 and 500 nm.
Claim 9
Dependent Claim
15 words
A method according to claim 6 wherein a colorimeter is used to measure the absorbance.
Claim 10
Dependent Claim
28 words
A method according to claim 6 wherein the determination of urea from the absorbance is made within 30 minutes after the mixing of the sample and the reagent.
Claim 11
Dependent Claim
13 words
A method according to claim 6 wherein said dipolar aprotic solvent is dImethylformamide.
Claim 12
Dependent Claim
14 words
A method according to claim 6 wherein said solution is acidified with an acid.
Claim 13
Dependent Claim
12 words
A method according to claim 11 wherein the acid is sulfuric acid.
Claim 14
Dependent Claim
55 words
A reagent for the determination of urea in biological fluids consisting of an acidified solution of p-dimethylaminobenzaldehyde in a dipolar aprotic solvent, said p-dimethylaminobenzaldehyde being present at a level between 0.1 to 10 gram percent, and the solution being acidified by an acidifying agent which is present in an amount between 1 to 30 percent.
Claim 15
Dependent Claim
55 words
A reagent for the determination of urea in biological fluids consisting of an acidified solution of p-dimethylaminobenzaldehyde in a dipolar aprotic solvent, said p-dimethylaminobenzaldehyde being present at a level between 0.1 to 10 gram percent, and the solution being acidified by an acidifying agent which is present in an amount between 1 to 30 percent.
Claim 16
Dependent Claim
13 words
A reagent according to claim 13 wherein said dipolar aprotic solvent is dimethylformamide.
Claim 17
Dependent Claim
14 words
A reagent according to claim 13 wherein said solution is acidified with an acid.
Claim 18
Dependent Claim
12 words
A reagent according to claim 15 wherein the acid is sulfuric acid.
Claim 19
Dependent Claim
13 words
A reagent according to claim 16 wherein said dipolar aprotic solvent is dimethylformamide.
Claim 20
Dependent Claim
41 words
A method for determining urea in biological fluids which comprises mixing a small sample of biological fluid to the reagent of claim 13 being between 1:100 and 1:25, and determining the concentration of the urea by means of measuring the absorbance.
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) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |