Preparation of some common fixatives

Fixatives :They are prervating agentsThe following fixative agents are in use for fixing various kinds of  animal tissues : 

1. Bouin's fluid (alcoholic). Dissolve 1 gm of picric acid in 250 ml of 90% alcohol. The Bouin's fluid or alcoholic picric acid is used to fix the tissues for microtomic sections. The alcoholic Bouin's fluid 

is removed from tissues by washing with 70% alcohol. 

2. Bouin's fluid (aqueous). It is prepared by adding excess of picric acid in a measured distilled 

water. Decant the saturated picric acid fluid. The aqueous Bouin's fluid is used to fix the tissue with 

the elements in situ. Picric acid is removed from tissues by washing with distilled water. 

3. Corrosive sublimate. It is prepared by adding 10 gm of corrosive sublimate to 3 ml of 

glacial acetic acid and 300 ml of distilled water. This fixative is removed from tissues by washing 

with 70% alcohol. Tissues are fixed within few seconds to 10 minutes. 

4. Formalin solution. 0.5 to 0.1 % or 5% solution of formalin is prepared. Formalin acts both as fixative as well as preservatives

5. Trichloro-acetic acid. 

Sublimate solution 6ml

Trichloro acetic acid 1 ml

Acetic acid 1 ml

This fixative is one of the bestdecalcifying fluid. 

6. Formol-picric-trichloro-acetic acid. 

Formalin (40%) 15 ml

Trichloro-acetic acid 0.5 gm 

Alcoholic picric acid solution 

(2% picric acid in 50% alcohol) 85 ml

7. Chromo-aceto-osmic acid. 

(a) Weak formula. 

Chromic acid 0.25% 

Osmic acid 0.1 % in water 

Glacial acetic acid 0.1 % 

This fluid is good for smalleranimals. 

(b) Strong formula. 

Chromic acid (1%) 15 ml

Osmic acid (2%) 4 ml

Glacial acetic acid 1 ml

Stock solution is prepared and mixed at the time of use. This fluid is good for large objects. 

8. Formol-acetic-alcohol (F.A.A.). 

Formalin (40%) 10 ml

Glacial acetic acid 5 ml

Ethyl alcohol (70%) 85 ml

F.A.A. fluid is good for fixing nematodes and plant material. 

9. Henking fluid. 

Water 80 ml

Glycerine  16 ml

Formic acid 1ml

Osmic acid (1 % 

Dahlia  0.4 ml

10. Acetic sublimate. 

Corrosive sublimate 6 gm

Distilled water 100 ml

Glacial acetic acid 2ml

11. Chromo-acetic acid (Flemming solution). 

Chromic acid 0.2 to 0.25% in distilled water. 

Acetic acid 0.1 % 

12. Picro-formol. 

Picric acid saturated aqueous solution  75 ml

Formol 25ml

Acetic acid 5ml

13. Zenker's fluid. 

Water distillate 10 ml

Potassium dichromate 2.5 g

Mercuric chloride 5 g

Sodium sulphate 1 g

Glacial acetic acid 5ml

This fixative is good for delicate objects. 

14. Mayer's albumen. 

White of egg 20 gm 

Glycerine 50 ml

Sodium salicylate 1 gm 

Mix the reagents, stir and filter. This is used to stick microtomy ribbons and small microorganisms, protozoans, etc. over slide. 

15. Carnoy's fluid I

Glacial acetic acid 1ml

Absolute alcohol 3 ml

This fluid is good for animal as well as plant material. 

16. Carnoy's fluid II. 

Glacial acetic acid 1 ml

Chloroform 3 ml

Absolute ethyl alcohol 1 ml

Reference

PRACTICAL ZOOLOGY VERTEBRATE BY SS LAL