Document Detail

Formaldehyde prepared from paraformaldehyde is stable.
MedLine Citation:
PMID:  10810978     Owner:  NLM     Status:  MEDLINE    
For critical histological investigations, tissue fixation is sometimes carried out in formaldehyde freshly prepared from paraformaldehyde by heating. The purity of formaldehyde produced in this way is superior to that of commercial stock solutions. We studied the stability of freshly prepared formaldehyde solutions by determination of pH and titration of acid, which reflect the formation of formic acid. It was found that very small amounts of acid are produced during the heating of paraformaldehyde. Prolonged heating or storage of freshly prepared formaldehyde for up to 8 days did not significantly increase the amount of acid. It was also found that heating of the paraformaldehyde is not necessary, since depolymerization may take place at room temperature. We conclude that formaldehyde prepared from paraformaldehyde remains stable for considerable periods of time, and it is therefore unnecessary to prepare it immediately prior to fixation. Also, in many cases, buffering of the fixative may be omitted, since only minor changes in the pH occur during fixation.
K G Helander
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biotechnic & histochemistry : official publication of the Biological Stain Commission     Volume:  75     ISSN:  1052-0295     ISO Abbreviation:  Biotech Histochem     Publication Date:  2000 Jan 
Date Detail:
Created Date:  2000-08-02     Completed Date:  2000-08-02     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9107378     Medline TA:  Biotech Histochem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  19-22     Citation Subset:  IM    
Laboratory of Membrane Biology, West Los Angeles Veterans Administration Hospital Center/UCLA, California 90073, USA.
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MeSH Terms
Drug Stability
Fixatives / isolation & purification*
Formaldehyde* / isolation & purification*
Formic Acids / analysis
Hot Temperature
Hydrogen-Ion Concentration
Liver / anatomy & histology
Grant Support
Reg. No./Substance:
0/Fixatives; 0/Formic Acids; 0/Polymers; 0/Solutions; 30525-89-4/paraform; 50-00-0/Formaldehyde; 64-18-6/formic acid

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