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How is formalin used to preserve biological specimens?
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aldehyde
Alcohols may be oxidized to give aldehydes, ketones, and carboxylic acids. The oxidation of organic compounds generally increases the number of bonds from carbon to oxygen, and it may decrease the number of bonds to hydrogen.
Formalin is an aqueous solution of formaldehyde, which is the simplest of the aldehydes.1
It preserves biological specimens primarily through its chemical reactivity with proteins. By reacting with these proteins, formaldehyde effectively cross-links them, which stabilizes the tissue structure and prevents decay. This same protein-reactive property is also why the compound is utilized as an embalming agent, a disinfectant, and in the tanning industry.1
Because formaldehyde is a known human carcinogen and is highly irritating to mucous membranes, it must be handled with extreme caution to ensure safety.1