US4801549A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the determination of a differential white blood cell count
Assignee: Bayer Corp
•
Filing: 1987-02-02
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Granted: 1989-01-31
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Expires: 2007-02-02
Abstract
Abstract This invention relates to a method for the rapid determination of a differential white blood cell count in a sample, which method comprises: (a) preparing a reagent solution comprising; formaldehyde or paraformaldehyde; a surfactant; a sugar or sugar alcohol; and a buffer; and (b) rapidly mixing the reagent solution with the sample to be analyzed to form a reaction mixture, wherein both the reagent solution and the sample are initially at room temperature; and (c) rapidly heating the reaction mixture to a temperature of from about 62 DEG C. to about 72 DEG C. in order to lyse the red blood cells in the sample and fix the white blood cells in the sample.
Inventors
- 👤 John F. Cremins
- 👤 Young R. Kim
- 👤 Michael J. Malin
- 👤 Louis D. Sclafani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:54
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/50; G01N33/5005; G01N33/5094; G01N1/00; G01N1/28; G01N1/30; G01N2001/305; Y; Y10; Y10T; Y10T436/00; Y10T436/10; Y10T436/101666; Y10T436/107497
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
160 words
A process for rapidly preparing a blood sample for a differential white blood cell count which comprises: (a) preparing a aqueous reagent solution comprising formaldehyde in a concentration of from about 4.5% to about 6.6% weight/volume; a surfactant; a sugar or sugar alcohol; and a pH buffer to maintain the pH of said reagent solution at between about 6.6 and 7.6; (b) contacting said reagent solution with a blood sample and rapidly mixing said reagent solution with the sample to form a uniform reaction mixture within about five seconds after initially contacting each other; (c) lysing red blood cells contained in said reaction mixture and fixing white blood cells contained in said reaction mixture by heating the reaction mixture to a temperature of from about 62° C. to about 72° C. within 30 seconds; and (d) staining at least a portion of white blood cells in the reaction mixture to yield a suspension of stained and unstained white blood cells.
Claim 2
Dependent Claim
160 words
A process for rapidly preparing a blood sample for a differential white blood cell count which comprises: (a) preparing a aqueous reagent solution comprising formaldehyde in a concentration of from about 4.5% to about 6.6% weight/volume; a surfactant; a sugar or sugar alcohol; and a pH buffer to maintain the pH of said reagent solution at between about 6.6 and 7.6; (b) contacting said reagent solution with a blood sample and rapidly mixing said reagent solution with the sample to form a uniform reaction mixture within about five seconds after initially contacting each other; (c) lysing red blood cells contained in said reaction mixture and fixing white blood cells contained in said reaction mixture by heating the reaction mixture to a temperature of from about 62° C. to about 72° C. within 30 seconds; and (d) staining at least a portion of white blood cells in the reaction mixture to yield a suspension of stained and unstained white blood cells.
Claim 3
Dependent Claim
37 words
The process of claim 1 which further comprises the step of passing said suspension of stained and unstained white blood cells through an electro optical detection system and differentially counting white blood cells present in said suspension.
Claim 4
Dependent Claim
24 words
The process of claim 1 wherein formaldehyde is present in said reagent solution in an amount of from about 5.3% to about 5.9% weight/volume.
Claim 5
Dependent Claim
25 words
The process of claim 1 wherein the buffer is such that it maintains the pH of said reagent solution between about 6.9 and about 7.3.
Claim 6
Dependent Claim
22 words
The process of claim 1 wherein said buffer comprises a mixture of Na 2 HPO 4 and NaH 2 PO 4 .
Claim 7
Dependent Claim
17 words
The process of claim 1 in which the staining step involves staining peroxidase active white blood cells.
Claim 8
Dependent Claim
21 words
The process of claim 6 wherein said staining step comprises rapidly mixing said reaction mixture with hydrogen peroxide and a chromogen.
Claim 9
Dependent Claim
10 words
The process of claim 7 where said chromogen is 4-chloro-1-naphthol.
Claim 10
Dependent Claim
25 words
The process of claim 1 wherein said surfactant comprises an alkali metal salt of an alkyl sulfate containing from about 10 to 16 carbon atoms.
Claim 11
Dependent Claim
14 words
The process of claim 9 wherein said surfactant comprises an alkali metal dodecyl sulfate.
Claim 12
Dependent Claim
12 words
The process of claim 10 wherein said surfactant is sodium dodecyl sulfate.
Claim 13
Dependent Claim
21 words
The process of claim 9 wherein said surfactant is present in said reagent solution in an amount of about 0.36 mM.
Claim 14
Dependent Claim
16 words
The process of claim 1 wherein said reagent solution further comprises an alkali metal chloride salt.
Claim 15
Dependent Claim
22 words
The process of claim 13 wherein said alkali metal chloride salt is selected from the group consisting of NaCl, KC1 and LiCl.
Claim 16
Dependent Claim
10 words
The process of claim 14 wherein said salt is NaCl.
Claim 17
Dependent Claim
26 words
The process of claim 14 wherein said salt is present in said reagent solution in an amount of from about 68 mM to about 103 mM.
Claim 18
Dependent Claim
24 words
The process of claim 1 wherein said sugar or sugar alcohol is selected from the group consisting of sucrose, fructose, dextrose, sorbitol and mannitol.
Claim 19
Dependent Claim
13 words
The process of claim 17 wherein said sugar or sugar alcohol is dextrose.
Claim 20
Dependent Claim
24 words
The process of claim 18 wherein dextrose is present in said reagent solution in an amount of from about 9.0% to about 13.5% weight/volume.
Claim 21
Dependent Claim
24 words
The process of claim 19 wherein dextrose is present in said reagent solution in an amount of from about 11.0% to about 12.0% weight/volume.
Claim 22
Dependent Claim
13 words
The process of claim 17 wherein said sugar or sugar alcohol is sorbitol.
Claim 23
Dependent Claim
24 words
The process of claim 21 wherein sorbitol is present in said reagent solution in an amount of from about 9.0% to about 13.5% weight/volume.
Claim 24
Dependent Claim
24 words
The process of claim 18 wherein sorbitol is present in said reagent solution in an amount of from about 11.0% to about 12.0% weight/volume.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-01-31 | 1992-08-01 | 1993-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-31 | 1996-08-01 | 1997-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-31 | 2000-08-01 | 2001-01-31 | $7700.00 | Window Closed / Lapsed |