True about formalin
Formalin is not used as preservative for chemical analysis because extraction of poison becomes difficult. PRESERVATIVES : 1. Saturated solution of NaCl - commonly used 2. Rectified spirit (95% alcohol )- Best preservative 3. 10% Formalin - for histopathological examination 4. 50% Glycerol - for virology 5. NaF - For Co, Cyanide, Alcohol poisoning. Avoid salts in Avoid Rectified Spirit in 1. Corrosive except phenol 2. Aconite 1. Alcohol 2. Formalin 3. Phenol