Purified Cotton
»Purified Cotton is the hair of the seed of cultivated varieties of Gossypium hirsutumLinné,or of other species of Gossypium(Fam.Malvaceae),freed from adhering impurities,deprived of fatty matter,bleached,and sterilized in its final container.
Packaging and storage— Package it in rolls of not more than 500g of a continuous lap,with a light-weight paper running under the entire lap,the paper being of such width that it may be folded over the edges of the lap to a distance of at least 25mm,the two together being tightly and evenly rolled,and enclosed and sealed in a well-closed container.It may be packaged also in other types of containers if these are so constructed that the sterility of the product is maintained.
Labeling— Its label bears a statement to the effect that the sterility cannot be guaranteed if the package bears evidence of damage or if the package has been opened previously.
Sterility á71ñ: meets the requirements.
Acidity or alkalinity— Thoroughly saturate about 10g with 100mLof recently boiled and cooled water,then with the aid of a glass rod press out two 25-mLportions of the water into white porcelain dishes.To one portion add 3drops of phenolphthalein TS,and to the other portion add 1drop of methyl orange TS:no pink color develops in either portion.
Residue on ignition á281ñ— Place about 5g,accurately weighed,in a porcelain or platinum dish,and moisten with 2Nsulfuric acid.Gently heat the cotton until it is charred,then ignite more strongly until the carbon is completely consumed:not more than 0.20%of residue remains.
Water-soluble substances— Place 10g,accurately weighed,in a beaker containing 1000mLof water,and boil gently for 30minutes,adding water as required to maintain the volume.Pour the water through a funnel into another vessel,and press out the excess water from the cotton with a glass rod.Wash the cotton in the funnel with two 250-mLportions of boiling water,pressing the cotton after each washing.Filter the combined extract and washings,and wash the filter thoroughly with hot water.Evaporate the combined extract and washings to a small volume,transfer to a tared porcelain or platinum dish,evaporate to dryness,and dry the residue at 105to constant weight:the residue weighs not more than 35mg (0.35%).
Fatty matter— Pack 10±0.01g in a Soxhlet extractor provided with a tared receiver,and extract with ether for 5hours at a rate such that the ether siphons over not less than four times per hour.The ether solution in the flask shows no trace of blue,green,or brownish color.Evaporate the extract to dryness,and dry at 105for 1hour:the weight of the residue does not exceed 70mg (0.7%).
Dyes— Pack about 10g in a narrow percolator,and extract slowly with alcohol until the percolate measures 50mL:when observed downward through a column 20cm in depth,the percolate may show a yellowish color,but neither a blue nor a green tint.
Other foreign matter— The pinches of it taken for the determination of Fiber lengthcontain no oil stains or metallic particles.
Fiber length and Absorbency— Remove it from its wrappings,and condition it for not less than 4hours in a standard atmosphere of 65±2%relative humidity at 21±1.1(70±2F),before determining the Fiber lengthand Absorbency.
Fiber length— Determine the fiber length of Purified Cotton as directed under Cotton—Fiber Length á691ñ:not less than 60%of the fibers,by weight,are 12.5mm or greater in length,and not more than 10%of the fibers,by weight,are 6.25mm or less in length.
Absorbency— Proceed as directed under Cotton—Absorbency Test á691ñ:submersion is complete in 10seconds at a temperature of 25,and the cotton retains not less than 24times its weight of water.
Auxiliary Information— Staff Liaison:Radhakrishna S Tirumalai,Scientist
Expert Committee:(GTB)General Toxicology and Biocompatibility
USP28–NF23Page 548
Phone Number:1-301-816-8339