Legend: + will adopt and implement; will not stipulate
Nonharmonized attributes: Characters, Microbial Enumeration Tests and Tests for Specified Microorganisms, Labeling, and Packaging and Storage (USP)
Specific local attributes: Foreign matter (EP)
Reagents and reference materials: Each pharmacopeia will adapt the text to take account of local reference materials and reagent specifications.
Corn Starch consists of the starch granules separated from the mature grain of corn [Zea mays Linnè (Fam. Gramineae)].
• A. Procedure: Examine under a microscope, using NLT 20× magnification and using a mixture of glycerin and water (1:1) as a mounting agent.
Acceptance criteria: It appears either as angular polyhedral granules of irregular sizes with diameters ranging from 223 µm, or as rounded or spheroidal granules of irregular sizes with diameters ranging from 2535 µm. The central hilum consists of a distinct cavity or two- to five-rayed cleft, and there are no concentric striations. Between orthogonally oriented polarizing plates or prisms, the starch granules show a distinct black cross intersecting at the hilum.
• B. Procedure
Sample solution: 20 mg/mL in water
Analysis: Boil for 1 min, and cool.
Acceptance criteria: A thin, cloudy mucilage is formed.
• C. Procedure
Sample solution: 1 mL of the mucilage obtained in Identification test B
Analysis: Add 0.05 mL of iodine and potassium iodide TS 2 to the Sample solution.
Acceptance criteria: An orange-red to dark blue color is produced, which disappears upon heating.
• Residue on Ignition 281: NMT 0.6%, determined on a 1.0-g sample
• Limit of Iron
Standard iron stock solution A: Equivalent to 10 µg/mL of iron prepared as directed under Iron 241
Standard iron stock solution B: 1 µg/mL of iron from Standard iron stock solution A in water
[NotePrepare immediately before use. ]
Standard iron solution: Transfer 10 mL of Standard iron stock solution B to a test tube, and add 2 mL of citric acid solution (2 in 10) and 0.1 mL of thioglycolic acid. Add 10 N ammonium hydroxide until the solution is distinctly alkaline to litmus, and dilute with water to 20 mL.
Sample solution: Shake 1.5 g of Corn Starch with 15 mL of 2 N hydrochloric acid, and filter. Transfer 10 mL of the filtrate to a test tube, add 2 mL of citric acid solution (2 in 10), and 0.1 mL of thioglycolic acid. Add 10 N ammonium hydroxide until the solution is distinctly alkaline to litmus, and dilute with water to 20 mL.
Acceptance criteria: After 5 min, any pink color in the Sample solution is not more intense than that in the Standard iron solution, corresponding to a limit of 10 ppm of iron.
• Limit of Sulfur Dioxide
Carbon dioxide: Use carbon dioxide, with a flow regulator that will maintain a flow of 100 ± 10 mL/min.
Bromophenol blue indicator solution: 0.2 mg/mL of bromophenol blue in dilute alcohol. Filter if necessary.
Hydrogen peroxide solution: Dilute 30% hydrogen peroxide with water to obtain a 3% solution. Just before use, add 3 drops of Bromophenol blue indicator solution, and neutralize to a violet-blue endpoint with 0.01 N sodium hydroxide. Do not exceed the endpoint.
Apparatus: Figure 1.
In this test, the sulfur dioxide is released from the sample 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-mL three-neck, round-bottom boiling flask, A; separatory funnel, B, having a capacity of 100 mL or greater; a gas inlet tube of sufficient length to permit introduction of the carbon dioxide within 2.5 cm of the bottom of the boiling flask; a reflux condenser, C, having a jacket length of 200 mm, and a delivery tube, E, connecting the upper end of the reflux condenser to the bottom of a receiving test tube, D. 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.
Sample: 25.0 g of Corn Starch
Analysis: Add 150 mL of water to the boiling flask. Close the stopcock of the separatory funnel, and begin the flow of carbon dioxide at a rate of 100 ± 5 mL/min through the Apparatus. Start the condenser coolant flow. Add 10 mL of Hydrogen peroxide solution to a receiving test tube. After 15 min, without interrupting the flow of carbon dioxide, remove the separatory funnel from the boiling flask, and transfer the Sample into the boiling flask with the aid of 100 mL of 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 80 mL of 2 N hydrochloric 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 mL of hydrochloric acid drain out. Boil the mixture for 1 h. Remove the receiving test tube, and transfer its contents to a 200-mL wide-necked, conical flask. Rinse the receiving test tube with a small portion of water, add the rinsing to the 200-mL conical flask, and mix. Heat on a water bath for 15 min, and allow to cool.
Add 0.1 mL of Bromophenol blue indicator solution, and titrate the contents with 0.1 N sodium hydroxide VS until the color changes from yellow to violet-blue. Perform a blank determination, and make any necessary correction (see Titrimetry 541).
Calculate the content, in ppm, of sulfur dioxide in the Sample taken:
Result = 1000 (32.03) VN/W
Acceptance criteria: NMT 50 ppm
• Limit of Oxidizing Substances
Sample solution: Transfer 4.0 g to a glass-stoppered, 125-mL conical flask, and add 50.0 mL of water. Insert the stopper, and swirl for 5 min. Transfer to a glass-stoppered, 50-mL centrifuge tube, and centrifuge to clarify. Transfer 30.0 mL of the clear supernatant to a glass-stoppered, 125-mL conical flask. Add 1 mL of glacial acetic acid and 0.51.0 g of potassium iodide. Insert the stopper, swirl, and allow to stand for 2530 min in the dark. Add 1 mL of starch TS.
Analysis: Titrate with 0.002 N sodium thiosulfate VS to the disappearance of the starchiodine color. Perform a blank determination, and make any necessary correction. Each mL of 0.002 N sodium thiosulfate is equivalent to 34 µg of oxidant, calculated as hydrogen peroxide.
Acceptance criteria: NMT 1.4 mL of 0.002 N sodium thiosulfate is required (20 ppm, calculated as H2O2).
• Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62: The total aerobic microbial count does not exceed 1000 cfu/g; the total combined molds and yeasts count does not exceed 100 cfu/g; and it meets the requirements of the test for the absence of Escherichia coli. Where it is intended for use in preparing Absorbable Dusting Powder, it also meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa.
• Loss on Drying 731: Dry 1 g at 130 for 90 min: it loses NMT 15.0% of its weight.
• pH 791: 4.07.0
Sample solution: Prepare a slurry by weighing 5.0 g of Corn Starch, transferring to a suitable nonmetallic container, and adding 25.0 mL of freshly boiled and cooled water.
Analysis: Agitate continuously at a moderate rate for 1 min. Stop the agitation, and allow to stand for 15 min. Determine the pH to the nearest 0.1 unit.
• Packaging and Storage: Preserve in well-closed containers. No storage requirements specified.
• 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.
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USP35NF30 Page 1973Pharmacopeial Forum: Volume No. 35(3) Page 687