FIXATIVE FOR FIXING BIOLOGICAL MATERIALS

Abstract

A fixative for fixing biological materials contains a depot agent, preferably a polyamine and especially hexamethylenetetramine, which reacts chemically with positively charged ions, especially H+ from an acid, while forming a fixative, where the fixative is an aldehyde and especially formaldehyde, which in turn reacts chemically with the biological material to be fixed in order to fix it and is consumed in doing so. By adjusting the pH of a solution containing the depot agent, a chemical equilibrium reaction occurs between the depot agent, fixative and biological material, so that just as much fixative is continuously formed as can be immediately consumed by the biological material. With that, the fixative, and especially the hazardous formaldehyde, cannot escape. Thus, an externally formaldehyde-free fixative that at the same time has the excellent fixative properties of formaldehyde is created.

Description

EXAMPLE

A solution of the following chemicals, in percent by weight, was formed, and its pH was adjusted to 3.0-4.0:

1%        hexamethylenetetramine
1%        citric acid
1%        ascorbic acid
2%        ethylene glycol
0.05%     surfactant
0.01%     geraniol
0.01%     citral
Remainder water to 100%

This solution was tested on stool samples and flawlessly preserved them for 30 days. 3.5 mL solution was used for the stool test. Solutions containing hexamethylenetetramine in a concentration up to 1% do not have to be labeled as hazardous substances. The dose of hexamethylenetetramine that is dangerous for an adult is 4 g. The amount of hexamethylenetetramine in the 3.5 mL of solution thus is extremely far below the hazardous concentration. The solution is neither combustible nor highly corrosive nor caustic. Absorption through the skin or respiratory tract is excluded. Thus, all in all, an improvement of working and transport safety is ensured.

The amounts indicated above can be modified in each case according to application. For example, the value of 1 wt % hexamethylenetetramine is preferred, since at this amount there is no legal labeling requirement as a hazardous substance. For many application purposes, in which larger amounts of fixative are required, this value can however also be increased considerably, and then the solution will require labeling.

Also, the said value of 1 wt % citric acid, which is primarily responsible for adjusting the pH, can be matched to requirements in order to shift the described equilibrium reaction in the reaction of the formation of more formaldehyde.

The other indicated values can easily be varied by the specialist in each case according to the desired properties. One should note here that water is not the only possibility for the rest of the formulation; other aqueous solutions or other suitable solvents such as alcohols are also possibilities.

The following substances are also possibilities as depot agents:

• • Protectol HT, from BASF containing
    • CAS Number: 4719-04-4
    • EINEC Number: 225-208-0
    • Molecular Formula: C₉H₂₁N₃O₃
    • Molecular Weight: 219
    • Chemical Name: 1,3,5-tris-(2-hydroxyethyl)-1,3,5-hexahydrotriazine, 1,3,5-triazine-1,3,5(2H,4H,6H)-triethanol
  • Protectol TD, from BASF containing
    • CAS Number: 5395-50-6
    • EINEC Number: 226-408-0
    • Molecular Formula: 262
    • Chemical Name: 1,3,4,6-tetrakishydroxymethyltetrahydro-imidazo(4,5)imidazole-2,5-dione, tetramethylolacetylenediureaThe following substances can also be used as depot agents:
• glutaraldehyde, glyoxal, chloralhydrate, propanal, butanal, ethanal, which each form complexes with NH₃.

Claims

1-13. (canceled)

14. A biological material fixative solution comprising a fixative formed by a reaction between a depot agent and positively charged ions, wherein the fixative is capable of being consumed by a biological material in equilibrium with the fixative in order to fix the biological material.

15. The biological material fixative solution of claim 14 wherein the fixative is an aldehyde.

16. The biological material fixative solution of claim 15 wherein the fixative is formaldehyde.

17. The biological material fixative solution of claim 14 wherein the depot agent is a polyamine.

18. The biological material fixative solution of claim 17 wherein the depot agent is hexamethylenetetramine.

19. The biological material fixative solution of claim 14 wherein the depot agent is a triazine.

20. The biological material fixative solution of claim 14 wherein the depot agent is an imidazole.

21. The biological material fixative solution of claim 14 further comprising at least one acid and wherein the pH of the solution is between 3.0 and 7.0.

22. The biological material fixative solution of claim 21 wherein the pH of the solution is between 3.5 and 4.0.

23. The biological material fixative solution of claim 21 wherein the acid is selected from the group consisting of citric acid, ascorbic acid, acetic acid, formic acid and mixtures thereof.

24. The biological material fixative solution of claim 14 wherein the solution is buffered and has a pH of between 4.5 and 11.

25. The biological material fixative solution of claim 14 further comprising at least one of the following adjuvants: an antioxidation agent;a moisturizer;a wetting aid; andfragrances.

26. The biological material fixative solution of claim 14 wherein the solution comprises: 1-15% by weight hexamethylenetetramine;1-15% by weight citric acid;1-15% by weight ascorbic acid;2-15% by weight ethylene glycol;0.05-5% by weight surfactant;0.01-1% by weight geraniol; and0.01-1% by weight citral.

27. The biological material fixative solution of claim 14 wherein the solution comprises: 1% by weight hexamethylenetetramine;1% by weight citric acid;1% by weight ascorbic acid;2% by weight ethylene glycol;0.05% by weight surfactants;0.01% by weight geraniol; and0.01% by weight citral.

28. The biological material fixative solution of claim 14 wherein the solution is formaldehyde-free.

29. The biological material fixative solution of claim 14 wherein the solution is aldehyde-free.

30. A biological material fixative precursor comprising a depot agent and an acid and capable of producing a biological material fixative from a reaction between the depot agent and the acid and wherein the fixative is capable of fixing a biological material by being consumed by the biological material in equilibrium with the fixative.

31. The biological material fixative precursor of claim 30 wherein the precursor is in powder form, tablet form or is a coating on a container.

32. The biological material fixative precursor of claim 30 wherein the precursor is in solution.

33. A biological material fixative solution comprising a fixative formed by the reaction between the depot agent and the acid of the biological material fixative precursor of claim 30.

34. The biological material fixative solution of claim 33 wherein the solution is formaldehyde-free.

35. The biological material fixative solution of claim 33 wherein the solution is aldehyde-free.

36. A method of fixing a biological material, the method comprising: reacting a depot agent and positively charged ions to produce a biological material fixative; andcontacting the biological material with the fixative to facilitate consumption of the fixative by the biological material in equilibrium with the fixative.

37. The method of claim 36 wherein the depot agent is a polyamine.

38. The method of claim 37 wherein the depot agent is a hexamethylenetetramine.

39. The method of claim 36 wherein the depot agent is a triazine.

40. The method of claim 36 wherein the depot agent is an imidazole.

41. The method of claim 36 wherein the fixative is not formaldehyde.

42. The method of claim 36 wherein the fixative is not an aldehyde.