BASIC EM FIXATIVES AND BUFFERS
0.2M SODIUM CACODYLATE BUFFER
Note : addition of acid
produces Arsenic gas, handle in fume cupboard.
Sodium Cacodylate 4.28 grams
Distilled water 100 mls
For pH 7.2 add 8.4 mls of 0.2N Hydrochloric Acid to 100 mls of the Sodium cacodylate buffer.
For pH 7.4 add 5.6 mls of 0.2N Hydrochloric Acid to 100 mls of the Sodium cacodylate buffer.
0.2M SORENSEN'S SODIUM PHOSPHATE BUFFER
For pH 7.2 :- Add 72 mls of 0.2M
Dibasic Sodium Phosphate (Na2 HPO4 2H2O - 35.61 g/l).
to 28 mls of 0.2M Monobasic Sodium Phosphate (Na H2PO4 2H2O -
31.21 g/l).
For pH 7.4 :- Add 81 mls of 0.2M
Dibasic Sodium Phosphate
to 19 mls of 0.2M Monobasic Sodium Phosphate
2.5% GLUTARALDEHYDE IN 0.1M BUFFER
10mls 25% Glutaraldehyde
50 mls 0.2M Phosphate or Cacodylate Buffer at required pH
40 mls Distilled Water
Store at 4oC - Use within 2 weeks. Make up fresh before use.
1.6% PARAFORMALDEHYDE+ 2.5% GLUTARALDEHYDE IN 0.1M BUFFER
10 mls 16% Paraformaldehyde
10 mls 25% Glutaraldehyde
50 mls 0.2M Phosphate or Cacodylate Buffer at required pH
35 mls Distilled Water
Store at 4oC - Use within 2 weeks. Make up fresh before use.
1% OSMIUM TETROXIDE
0.1g Osmium Tetroxide crystals
10 mls Distilled Water
Allow to dissolve for 24 hrs. Store in dark glass bottle in fume cupboard, keeps two weeks.
NOTE - Vapour from all fixatives are highly TOXIC and should be handled with gloves and in the fume cupboard.