Absorbent Gauze
»Absorbent Gauze is cotton,or a mixture of cotton,and not more than 53.0percent,by weight,of rayon,and is in the form of a plain woven cloth conforming to the standards set forth herein.Absorbent Gauze that has been rendered sterile is packaged to protect it from contamination.
NOTE—Condition all Absorbent Gauze for not less than 4hours in a standard atmosphere of 65±2%relative humidity at 21±1.1before determining the weight,thread count,and absorbency.Remove the Absorbent Gauze from its wrappings before placing it in the conditioning atmosphere,and if it is in the form of bolts or rolls,cut the quantity necessary for the various tests from the piece,excluding the first two and the last two meters when the total quantity of Gauze available so permits.
Packaging and storage— Preserve in well-closed containers.Absorbent Gauze that has been rendered sterile is so packaged that the sterility of the contents of the package is maintained until the package is opened for use.
Labeling— Its type or thread count,length,and width and the number of pieces contained are stated on the container,and the designation “non-sterilized”or “not sterilized”appears prominently thereon unless the Gauze has been rendered sterile,in which case it may be labeled to indicate that it is sterile.The package label of sterile Gauze indicates that the contents may not be sterile if the package bears evidence of damage or has been previously opened.
The name of the manufacturer,packer,or distributor is stated on the package.
General characteristics— Absorbent Gauze is white cloth of various thread counts and weights.It may be supplied in various lengths and widths,and in the form of rolls or folds.
The accompanying table designates for each commercial type the thread count and weight in g per square meter.
Type Threads per 2.54Cm Average Count,
Threads per
6.45Sq.Cm		 Weight,1g per
Sq.Meter
Warp Filling
I 41to 47 33to 39 76to 842 43.8to 55.8
II 30to 34 26to 30 57to 63 32.9to 41.9
III 26to 30 22to 26 49to 55 28.4to 36.2
IV 22to 26 18to 22 41to 47 24.5to 31.1
V 20to 24 16to 20 37to 43 22.5to 28.8
VI 18to 22 14to 18 33to 39 19.8to 25.2
VII 18to 22 8to 14 27to 35 18.1to 23.1
VIII 12to 16 8to 12 21to 27 12.1to 15.5
1  For Absorbent Gauze that contains purified rayon,increase these values by 2.5%.
2  For Type Irolled gauze,the range is 75to 85threads per 6.45sq.cm.
Thread count— If the dimensions of the piece permit,count the warp and filling threads of Absorbent Gauze in three separate 76.2-mm squares,not counting threads nearer any edge than one-tenth of the dimension of the fabric and not including the same threads in any two counts.For pieces not greater than 76.2mm in either dimension,count all the threads in three different places in that dimension of the piece.
Average the three counts for the warp and filling,respectively:the average lies within the ranges tabulated under General characteristics.
For Absorbent Gauze packaged in rolls,count the number of warp and filling threads in areas of 1.27cm square at five points evenly spread along the center line of the bandage,no point being within 30.5cm of either end of the bandage.
Length— Unfold or unroll it,smooth it without stretching it,and measure its length along the center line:the length is not less than 98.0%of that stated on the label.
Width— Measure the width at each of the points selected for the Thread:the average of the three measurements is within 1.6mm of the width stated on the label.
Weight— Weigh a piece of gauze of stated size:the weight,expressed in terms of g per m2,meets the requirements for weight under General characteristics.
Absorbency— Fold about 0.1m2into a 10-cm section.For Absorbent Gauze packaged in rolls,use the entire roll.Hold the folded or rolled Gauze horizontally almost in contact with the surface of water at approximately 25,and allow it to drop lightly upon the water:complete submersion takes place in not more than 30seconds.
Sterility á71ñ— Absorbent Gauze that has been rendered sterile meets the requirements.
Dried and ignited residue,Acid or alkali,and Dextrin or starch,in water extract— Place 20±0.1g in 500mLof water,and boil the mixture for 15minutes,adding boiling water as necessary to maintain the original volume.Pour the water through a funnel into a 1000-mLvolumetric flask,transfer the Absorbent Gauze to the funnel,press out the excess water with a glass rod,and wash it with two 250-mLportions of boiling water,pressing the gauze after each washing.Cool the combined washings,dilute to volume,and mix.Then apply the following tests.
Dried residue— Evaporate 400mLof the extract,filtering if necessary,in a suitable dish on a steam bath,and dry the residue at 105to constant weight:the weight of the residue so obtained does not exceed an amount,in mg,calculated by the formula:
80–0.6C,
in which Cis the corrected percentage of cotton (50mg maximum,or 0.6%).
Ignited residue— Ignite the dried residue in a muffle furnace at a dull-red heat to constant weight:the weight of the ignited residue does not exceed an amount,in mg,calculated by the formula:
20–0.14C,
in which Cis the corrected percentage of cotton (13mg maximum,or 0.16%).
Acid or alkali— To separate 200-mLportions of the extract,add 3drops of phenolphthalein TSand 1drop of methyl orange TS,respectively:no pink color develops in either portion.
Dextrin or starch— To a 200-mLportion of the extract add 1drop of iodine TS:no red,violet,or blue color develops.
Residue on ignition— Place about 5g,accurately weighed,in a suitable dish,and moisten with 2Nsulfuric acid.Gently heat the mixture until it is charred,then ignite more strongly until the carbon is completely consumed:the weight of the residue corresponds to not more than the percentage of the weight of the Gauze,calculated by the formula:
0.002C+0.015(100–C),
in which Cis the corrected percentage of cotton (0.89%maximum).
Fatty matter— Pack 10±0.01g in a continuous-extraction thimble with a tared flask,and extract with ether for 5hours,adjusting the rate so that the ether siphons not less than four times per hour.The ether extract in the flask shows no trace of blue,green,or brownish color.Evaporate the extract to dryness,and dry at 105to constant weight:the weight of the residue does not exceed an amount,in mg,calculated by the formula:
0.4C+30,
in which Cis the corrected percentage of cotton (70mg maximum,or 0.7%).
Alcohol-soluble dyes— Pack 10g in a narrow percolator,and extract slowly with alcohol until the percolate measures 50mL:when observed downward in a column 20cm in depth,the percolate may show a yellowish color,but neither a blue nor a green tint.
Cotton and rayon content—
Sulfuric acid solution (59.5%by weight)—Add sulfuric acid slowly to water until the specific gravity,determined at 20,is between 1.4902and 1.4956.
Procedure— Place about 500mg of Absorbent Gauze,previously bleached and dried at 110to constant weight and accurately weighed,in a glass-stoppered,125-mLflask,add 50.0mLof Sulfuric acid solution,and shake by mechanical means for 30minutes.Pass the mixture through a tared sintered-glass crucible,using three 10-mLportions of Sulfuric acid solutionto rinse the flask and applying suction each time to drain the acid.Wash the residue in the crucible with 50mLof 2Nsulfuric acid,then wash it with water until the filtrate is neutral to litmus.Add 40mLof 6Nammonium hydroxide to the crucible,allow the residue to soak for 10minutes,then apply suction to remove the liquid.Similarly wash the residue with three 50-mLportions of water,allowing the residue to soak for 15minutes each time.Dry the residue at 105to 110to constant weight.Calculate C,the corrected percentage of cotton,taken by the formula:
[100(1.046J/G)–1.6],
in which Jis the weight,in mg,of the residue,Gis the weight,in mg,of the portion of Absorbent Gauze taken,and 1.046and 1.6are empirical correction factors.Calculate R,the corrected percentage of rayon,taken by the formula:
100–C.
Auxiliary Information— Staff Liaison:Radhakrishna S Tirumalai,Scientist
Expert Committee:(GTB)General Toxicology and Biocompatibility
USP28–NF23Page 890
Phone Number:1-301-816-8339