Add the following:
Corn Starch
»Corn Starch consists of the starch granules separated from the mature grain of corn [Zea maysLinné(Fam.Gramineae)].
Labeling— Where Corn Starch is intended for use in preparing Absorbable Dusting Powder,it is so labeled,and the label states that it must be subjected to further processing during the preparation of Absorbable Dusting Powder.
Identification—
A: Under a microscope,using not less than 20×magnification and using a mixture of glycerin and water (1:1)as a mounting agent,it appears either as angular polyhedral granules of irregular sizes with diameters ranging from about 2µm to about 23µm,or as rounded or spheroidal granules of irregular sizes with diameters ranging from about 25µm to about 35µm.The central hilum consists of a distinct cavity or two-to five-rayed cleft,and there are no concentric striations.Between crossed nicol prisms,the starch granules show a distinct black cross intersecting at the hilum.
B: Suspend 1g of it in 50mLof water,boil for 1minute,and cool:a thin,cloudy mucilage is formed.
C: Iodine solution—Dissolve 12.7g of iodine and 20g of potassium iodide in water,and dilute with water to 1000.0mL.To 10.0mLof this solution,add 0.6g of potassium iodide,and dilute with water to 100.0mL.Prepare immediately before use.
Procedure— To 1mLof the mucilage obtained in Identification test B,add 0.05mLof Iodine solution:an orange-red to dark blue color is produced,which disappears on heating.
Microbial limits á61ñ— The total aerobic microbial count does not exceed 1000cfu per g,the total combined molds and yeasts count does not exceed 100cfu per g,and it meets the requirements of the test for the absence ofEscherichia coli.Where it is intended for use in preparing Absorbable Dusting Powder,it also meets the requirements of the tests for absence of Staphylococcus aureusand Pseudomonas aeruginosa.
pHá791ñ— Prepare a slurry by weighing 5.0g of Corn Starch,transferring to a suitable nonmetallic container,and adding 25.0mLof freshly boiled and cooled water.Agitate continuously at a moderate rate for 1minute.Stop the agitation,and allow to stand for 15minutes.Determine the pHto the nearest 0.1unit:the pH,determined potentiometrically,is between 4.0and 7.0.
Loss on drying á731ñ— Dry about 1g,accurately weighed,at 130for 90minutes:it loses not more than 15.0%of its weight.
Residue on ignition á281ñ: not more than 0.6%,determined on a 1.0-g test specimen.Ignition temperature 600±50.
Limit of iron— Shake 1.5g of Corn Starch with 15mLof 2Nhydrochloric acid,and filter.Transfer 10mLof the filtrate to a test tube,add 2mLof citric acid solution (2in 10),0.1mLof thioglycolic acid,and mix.Add 10Nammonium hydroxide until the solution is distinctly alkaline to litmus,dilute with water to 20mL,and mix(Test Solution).Prepare a Standard Iron Solutioncontaining the equivalent of 10µg of iron per mLas directed under Iron á241ñ.Immediately before use,quantitatively dilute an accurately measured volume of this solution with water to obtain a Diluted Standard Iron Solutioncontaining the equivalent of 1µg of iron per mL.Prepare the Standard Solutionby transferring 10mLof the Diluted Standard Iron Solutionto a test tube and proceeding in the same manner as directed for the preparation of the Test Solution,beginning with “add 2mLof citric acid solution (2in 10).”After 5minutes,any pink color in the Test Solutionis not more intense than that in the Standard Solution,corresponding to a limit of 10µg of iron per g.
Limit of oxidizing substances— Transfer 4.0g to a glass-stoppered,125-mLconical flask,and add 50.0mLof water.Insert the stopper,and swirl for 5minutes.Transfer to a glass-stoppered,50-mLcentrifuge tube,and centrifuge to clarify.Transfer 30.0mLof the clear supernatant to a glass-stoppered,125-mLconical flask.Add 1mLof glacial acetic acid and 0.5g to 1.0g of potassium iodide.Insert the stopper,swirl,and allow to stand for 25to 30minutes in the dark.Add 1mLof starch TS,and titrate with 0.002Nsodium thiosulfate VSto the disappearance of the starch-iodine color.Perform a blank determination,and make any necessary correction.Each mLof 0.002Nsodium thiosulfate is equivalent to 34µg of oxidant,calculated as hydrogen peroxide.Not more than 1.4mLof 0.002Nsodium thiosulfate is required (20µg per g,calculated as H2O2).
Limit of sulfur dioxide: not more than 50µg per g.
Reagents—
Carbon dioxide— Use carbon dioxide,with a flow regulator that will maintain a flow of 100±10mLper minute.
Bromophenol blue indicator solution— Dissolve 100mg of bromophenol blue in 100mLof dilute alcohol (1in 5),and filter if necessary.
Hydrogen peroxide solution— Dilute 30%hydrogen peroxide with water to obtain a 3%solution.Just before use,add 3drops of Bromophenol blue indicator solution,and neutralize to a violet-blue endpoint with 0.01Nsodium hydroxide.Do not exceed the endpoint.
Apparatus— In this test,the sulfur dioxide is released from the test specimen in a boiling acid medium and is removed by a stream of carbon dioxide.The separated gas is collected in a dilute hydrogen peroxide solution where the sulfur dioxide is oxidized to sulfuric acid and titrated with standard alkali.The apparatus consists essentially of a 500-mLthree-neck,round-bottom boiling flask,a separatory funnel having a capacity of 100mLor greater,a gas inlet tube of sufficient length to permit introduction of the carbon dioxide within 2.5cm of the bottom of the boiling flask,a reflux condenser having a jacket length of 200mm,and a delivery tube connecting the upper end of the reflux condenser to the bottom of a receiving test tube.Apply a thin film of stopcock grease to the sealing surfaces of all of the joints except the joint between the separatory funnel and the boiling flask,and clamp the joints to ensure tightness.
Procedure— Add 150mLof water to the boiling flask.Close the stopcock of the separatory funnel,and begin the flow of carbon dioxide at a rate of 100±5mLper minute through the Apparatus.Start the condenser coolant flow.Add 10mLof Hydrogen peroxide solutionto a receiving test tube.After 15minutes,without interrupting the flow of carbon dioxide,remove the separatory funnel from the boiling flask,and transfer 25.0g of test specimen into the boiling flask with the aid of 100mLof water.Apply stopcock grease to the outer joint of the separatory funnel,and replace the separatory funnel in the boiling flask.Close the stopcock of the separatory funnel,and add 80mLof 2Nhydrochloric acid to the separatory funnel.Open the stopcock of the separatory funnel to permit the hydrochloric acid solution to flow into the boiling flask,guarding against the escape of sulfur dioxide into the separatory funnel by closing the stopcock before the last few mLof hydrochloric acid drain out.Boil the mixture for 1hour.Remove the receiving test tube,and transfer its contents to a 200-mLwide-necked,conical flask.Rinse the receiving test tube with a small portion of water,add the rinsing to the 200-mLconical flask,and mix.Heat on a water bath for 15minutes,and allow to cool.Add 0.1mLof Bromophenol blue indicator solution,and titrate the contents with 0.1Nsodium hydroxide VSuntil the color changes from yellow to violet-blue,with the color change lasting for at least 20seconds.Perform a blank determination,and make any necessary correction (see Titrimetry á541ñ).Calculate the content,in µg per g,of sulfur dioxide in the test specimen taken by the formula:
1000(32.03)VN/W,
in which 32.03is the milliequivalent weight of sulfur dioxide;Vis the volume,in mL,of titrant consumed;Nis the normality of the titrant;and Wis the weight,in g,of test specimen taken.NF23
Auxiliary Information— Staff Liaison:Justin Lane,B.S.,Scientific Associate
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3088
Pharmacopeial Forum:Volume No.30(5)Page 1862
Phone Number:1-301-816-8323