Pyroxylin

Cellulose,nitrate.
Pyroxylin [9004-70-0].
»Pyroxylin is a product obtained by the action of a mixture of nitric and sulfuric acids on cotton and consists chiefly of cellulose tetranitrate (C12H16N4O18)n.
NOTE—Dry Pyroxylin is a light yellow,matted mass of filaments,resembling raw cotton in appearance,but harsh to the touch.It is exceedingly flammable,burning,when unconfined,very rapidly and with a luminous flame.When kept in well-closed bottles and exposed to light,it is decomposed with the evolution of nitrous vapors,leaving a carbonaceous residue.
Pyroxylin available commercially is moistened with about 30percent of alcohol or other suitable solvent.The alcohol or other solvent must be allowed to evaporate from the Pyroxylin to yield the dried substance described in this Pharmacopeia.Pyroxylin moistened with alcohol or other solvent may be used in the tests set forth in this monograph,provided the weight of test specimen taken corresponds to the specified amount of dry Pyroxylin.
Packaging and storage— Preserve loosely packed in cartons,protected from light.
Labeling— The label bears a caution statement to the effect that Pyroxylin is highly flammable.
Viscosity á911ñ— Dissolve 48.8g in a mixture of 88g of alcohol and 193.2g of toluene,and when solution is complete,add 70g of ethyl acetate,and mix.Transfer the solution to the cup of a rotational type of viscosimeter,adjust the temperature to 25,and determine the viscosity,making certain that the apparent viscosity reaches equilibrium before taking the final reading:the viscosity is between 110and 147poises.
Residue on ignition á281ñ— Saturate about 500mg,accurately weighed,with alcohol in a dish placed in cold water,and ignite the Pyroxylin at the top.When combustion is complete,heat the dish to redness,and cool:not more than 0.3%of residue remains.
Acidity and water-soluble substances— Stir 1.0g with 20mLof water for 10minutes,and filter:the filtrate does not have an acid reaction to litmus.Evaporate 10mLof the filtrate on a steam bath to dryness,and dry the residue at 105for 1hour:not more than 1.5mg of residue remains.
Organic volatile impurities,Method Vá467ñ: meets the requirements.
Solvent— Use dimethyl sulfoxide as the solvent.
Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 1687
Phone Number:1-301-816-8389