US4003892A
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US
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Method of separating thionine and its N-methyl derivatives from each other
Assignee: Serva-Entwicklungslabor V Grothe Co
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Filing: 1976-03-18
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Granted: 1977-01-18
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Expires: 1996-03-18
Abstract
Abstract Mixtures of cationic thiazine dyes containing two or more members of the group consisting of thionine, azure A, azure B, azure C, and methylene blue may be resolved into pure individual compounds by column chromatography on slica gel using as a solvent system a mixture of water, acetic acid, and formic acid. The several fractions eluted sequentially from the column contain the pure individual dyes in the formate or acetate form. Because high solubility is essential for use of the dyes in staining blood smears, the acetates or formates are converted to the chlorides by adsorption on a solid substrate and contact with NaCl solution, elution with methanol, and recovery of the solid chlorides from the methanol solution.
Inventors
- 👤 Walter Lohr
- 👤 Norbert Grubhofer
- 👤 Inge Sohmer
- 👤 Dietrich Wittekind
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:36
CPC Classifications
C; C09; C09B; C09B21/00
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
163 words
A method of separating at least two mixed, cationic dyes of the group consisting of thionine, azure A, azure B, azure C, and methylene blue from each other which comprises: a. subjecting said mixed dyes to chromatography on a column of silica gel with a solvent system consisting essentially of water, formic acid, and acetic acid until an eluate is discharged from said column; b. separately collecting sequentially discharged fractions of said eluate, one of said fractions containing only one of the separated dyes, each dye being present in said fractions as the formate or acetate; c. adsorbing the separated dye as the formate or acetate from said one fraction on an adsorbent substrate; d. exposing the adsorbed dye to an aqueous sodium chloride solution until the dye is converted from the formate or acetate form to the chloride form; and e. eluting the dye in the chloride form from said substrate with an organic solvent volatile in a vacuum at 37° C.
Claim 2
Independent Claim
163 words
A method of separating at least two mixed, cationic dyes of the group consisting of thionine, azure A, azure B, azure C, and methylene blue from each other which comprises: a. subjecting said mixed dyes to chromatography on a column of silica gel with a solvent system consisting essentially of water, formic acid, and acetic acid until an eluate is discharged from said column; b. separately collecting sequentially discharged fractions of said eluate, one of said fractions containing only one of the separated dyes, each dye being present in said fractions as the formate or acetate; c. adsorbing the separated dye as the formate or acetate from said one fraction on an adsorbent substrate; d. exposing the adsorbed dye to an aqueous sodium chloride solution until the dye is converted from the formate or acetate form to the chloride form; and e. eluting the dye in the chloride form from said substrate with an organic solvent volatile in a vacuum at 37° C.
Claim 3
Dependent Claim
48 words
A method as set forth in claim 1, wherein said solvent system contains said water, said formic acid, and said acetic acid in substantially the same ratio as a liquid mixture prepared from 95 parts by volume aqueous, 10% glacial acetic acid solution and 5 parts formic acid.
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) | 1980-01-18 | 1980-07-19 | 1981-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-18 | 1984-07-19 | 1985-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-18 | 1988-07-19 | 1989-01-18 | $7700.00 | Window Closed / Lapsed |