Process for the crystalline precipitation of chromogens

• US 4,295,857 A
• Filed: 04/03/1980
• Issued: 10/20/1981
• Est. Priority Date: 04/06/1979
• Status: Expired due to Term

• Current Assignee: Erwin Braun, Peter Schuler
• Original Assignee: Erwin Braun, Peter Schuler
• Inventors: Schuler, Peter, Braun, Erwin
• Primary Examiner(s): GARRIS, BRADLEY R
• Application Number:
  US06/136,911
• Time in Patent Office: 565 Days
• Field of Search: 23/295 R, 23/300, 23/301, 23/230 B, 260/707, 427/2, 427/398.1, 128/760
• US Class Current: 23/301
• CPC Class Codes: C12Q 1/00 Measuring or testing processes involving enzymes, nucleic acids or microorganisms measuring or testing apparatus with condition measuring or sensing means, e.g. colony counters, C12M1/34; Compositions therefor; Processes of preparing such compositions
• CPC Class Codes: G01N 33/52 Use of compounds or compositions for colorimetric, spectrophotometric or fluorometric investigation, e.g. use of reagent paper and including single- and multilayer analytical elements immunological elements G01N33/54386; involving labelled immunochemicals G01N33/58; for haemoglobin or occult blood G01N33/72

Abstract

The invention contemplates a process for the crystalline precipitation of a chromogen from solution thereof in a solvent and within a capillary. The process involves first initiating a course of crystalline precipitation of the chromogen by initially and locally supersaturating the solution within the capillary, and thereafter evaporating the solvent at a rate and in an environment sufficient for further crystallization to proceed unimpeded by local supersaturation.

Claims

1. A process for crystalline precipitation of a chromogen from solution thereof in a solvent and within a capillary, comprising the steps of initiating a course of crystalline precipitaton of the chromogen by initially and locally supersaturating the solution within the capillary, and thereafter evaporating the solvent at a rate and in an environment sufficient for further crystallization to proceed unimpeded by local supersaturation.

2. A process according to claim 1, characterized by the fact that, from a series of chemically homogolous solvents having substantially the same solution properties, solvent is selected having a rate of evaporation at a given temperature such that upon said further crystallization the solution no longer passes into a supersaturated condition during the entire further course of crystallization.

3. A process according to claim 1 or 2 characterized by the fact that a solvent mixture is used as solvent.

4. A process according to claim 3, characterized by the fact that the solvent mixture consists of a component which dissolves the chromogen and of a component which does not substantially dissolve the chromogen.

5. A process according to claim 4, characterized by the fact that such an amount of the chromogen-dissolving component is used as is necessary in order at least to dissolve a predetermined amount of chromogen and that the condition of initial supersaturation is obtained by adding a suitable quantity of the non-dissolving component.

6. A process according to claim 4, characterized by the fact that an ether is used as dissolving component.

7. A process according to claim 4, characterized by the fact that 4-aminophenazone is used as chromogen, a dialkyl ether is used as non-dissolving component, and methanol is used as dissolving component.

8. A process according to claim 7, characterized by the fact that the dialkyl ether is a symmetrical dialkyl ether having 1 to 5 carbon atoms per side chain.

9. A process according to claim 7, characterized by the fact that the dialkyl ether is diisopropyl ether.

10. A process according to claim 7, characterized by the fact that as dissolving component 2 to 6 vol. % methanol per 100 μ

g of 4-aminophenazone is used.

11. A process according to claim 7, characterized by the fact that 2.95 vol.% methanol per 100 μ

g of 4-aminophenazone is used.

12. A process according to claim 1, characterized by the fact that the temperature of the solvent for its evaporation is so selected that crystallization takes place but supersaturation is avoided.

13. A process according to claim 1, characterized by the fact that in order to avoid supersaturation upon the further crystallization the solution is brought to a temperature at which the solvent evaporates at a minumum rate such that unimpeded crystallization is achieved.

14. A process according to claim 13, characterized by the fact that the temperature is less than -30°

C.

15. A process according to claim 13, characterized by the fact that the temperature is less than or equal to -50°

C.

16. A process according to claim 13, characterized by the fact that the temperature is maintained until the solvent has completely evaporated.

17. A process according to claim 1, characterized by the fact that after the precipitation of the chromogen after-drying with the application of a vacuum is effected.

18. A process according to claim 1, characterized by the fact that crystallization seeds are introduced into the capillaries before they are filled with the chromogen-containing solution.

19. A process according to claim 18, characterized by the fact that fine crystals of the chromogen to be precipitated out are used as crystallization seeds.