Collodion wool
Collodion wool (dinitrocellulose, colloxylinum) is a form of nitrated cellulose , which can be used e.g. B. obtained by the action of nitric and sulfuric acid on cotton . The nitration ( esterification ) is carried out up to a nitrogen content of 10.6–12.2%. As a collodion, it is used in medicine as a sealant for smaller wounds and in the paint and photographic industries. It is also used in the manufacture of blasting gelatine and adhesives . The fact that almost no ash arises from its rapid, not too hot, but widely visible combustion also makes it popular in stage productions, where it is used as a "pyro floss" for pyrotechnic effects (often in close proximity to the actors).
Collodion wool feels a bit like cotton and rayon , but is a little harder. If it is lit, it burns with a yellow flame. When dry, it can explode by impact and / or blow.
Collodion wool is soluble in: acetone , concentrated acetic acid , mixtures of ether and alcohol . But it does not dissolve in water.
Identity check: 10 g collodion wool must dissolve in 250 ml of a solution of 30 parts ether and one part alcohol without leaving any residue.
Purity tests:
- for free acids: 1 g collodion wool is shaken with 20 ml water for 10 minutes. Then the water is filtered and litmus is added, which must react neutrally.
- for water-soluble substances: 10 ml are evaporated from the previous solution (filtered water from the purity test for free acids ). A maximum of 1.5 mg of residue may form in the process.
- Loss on drying : The collodion wool is dried to constant weight at 61 ° C. The weight loss should be between 23 and 28%. The residue obtained can be disposed of safely by dissolving it with acetone and an alcoholic potassium hydroxide solution for a few hours.
- Combustion residue: The collodion wool (0.2 g) is placed in a previously burned and weighed porcelain crucible. This is placed in a cold water bath. The collodion wool is moistened with alcohol, carefully lit and ashed. The residue must not exceed 0.5% of the weight of the collodion wool (i.e. 0.001 g).
Individual evidence
- ↑ Entry on collodion wool. In: Römpp Online . Georg Thieme Verlag, accessed on February 10, 2014.
literature
- Austrian Pharmacopoeia , Official Edition 2005, Verlag Österreich