Identification,
Infrared Absorption 
197S
—
[NOTE—Use the procedural blank, prepared as directed in the
Assay, to set the instrument.
]
Test solution—
Prepare as directed for the Assay preparation in the Assay.
Standard solution—
Prepare as directed for the Standard preparation in the Assay.
Cell size:
0.5 mm.
Defoaming activity—
Foaming solution—
Dissolve 500 µg of FD&C Blue No. 1 and 1 g of octoxynol 9 in 100 mL of water, except that where the Tablets are labeled as gelatin-coated, use 0.1 N hydrochloric acid instead of water.
Procedure—
[NOTE—For each test, employ a clean, unused, 250-mL glass jar.
] Transfer a quantity of finely powdered Tablets, equivalent to 20 mg of simethicone, to a clean, unused, cylindrical 250-mL glass jar, fitted with a 50-mm cap, containing 100 mL of
Foaming solution that has been warmed to 37
. Proceed as directed for
Procedure in the test for
Defoaming activity under
Simethicone, beginning with “Cap the jar.” The defoaming activity time does not exceed 45 seconds.
Assay—
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 50 mg of simethicone, to a round, narrow-mouth, screw-capped, 120-mL bottle, and proceed as directed in the
Assay under
Simethicone, beginning with “add 25.0 mL of toluene,” except that for Tablets labeled as gelatin-coated, shake for 30 minutes instead of 5 minutes. Calculate the quantity, in mg, of [–(CH
3)
2SiO–]
n in the portion of Tablets taken by the formula:
25C(AU / AS),
in which
C is the concentration, in mg per mL, of
USP Polydimethylsiloxane RS in the Standard solution, and
AU and
AS are the absorbances of the solution from the Tablets and the Standard solution, respectively.
