(B) Chemical Preservatives
(1) Fixing solutions
Aqueous solution of formalin (10 %), the quantity should be 10 times as much as the tissues. Fixing solutions have the properties of penetrating, killing, preserving and hardening tissues. Absolute ethyl and methyl alcohol are also used as preservatives.
Anticoagulants are substances that added to blood sample to avoid blood coagulation.
Anticoagulant other than heparin act by binding the calcium ion.
These include ethylene diamine tetra acetic acid (EDTA), sodium citrate, ammonium and potassium oxalate mixture, fluoride and potassium oxalate mixture and heparin.
(3) Bactericidal solutions:
These solutions are used when bacterial growth is to be kept at minimum.
Do not used on specimen for bacteriological examinations.
Formalin 10 % for faecal and urine samples.
Phenol 0.5 % aqueous solution or Merthiolate 1: 10000 for serum.