C13H17NO 203.28

2-Butenamide, N-ethyl-N-(2-methylphenyl)-.
N-Ethyl-o-crotonotoluidide [483-63-6].

Packaging and storage— Preserve in tight, light-resistant containers.

USP Reference standards 11— USP Crotamiton RS.

Identification—

Specific gravity 841: between 1.008 and 1.011 at 20.

Refractive index 831: between 1.540 and 1.543 at 20.

Residue on ignition 281: not more than 0.1%.

Bound halogen— Place 4 drops in a 3-mm (ID) test tube, and add calcium oxide to a height of 1 cm. Heat the tube in a flame, starting from the top, until the reaction is complete, then ignite for a short time. Transfer the contents to a beaker containing 10 mL of water, acidify with nitric acid, and filter. To the filtrate add 0.2 mL of silver nitrate solution (1 in 60): any opalescence obtained is not more than that obtained from a blank solution treated in the same manner.

Residual solvents 467: meets the requirements.

Assay— Transfer about 50 mg of Crotamiton, accurately weighed, to a 100-mL volumetric flask, add cyclohexane to volume, and mix. Transfer 10.0 mL of this solution to a 250-mL volumetric flask, dilute with cyclohexane to volume, and mix. Determine the absorbance of this solution and of a solution of USP Crotamiton RS in the same medium having a known concentration of about 20 µg per mL in 1-cm cells at the wavelength of maximum absorbance at about 242 nm, with a suitable spectrophotometer, using cyclohexane as the blank. Calculate the quantity, in mg, of C13H17NO in the Crotamiton taken by the formula: in which C is the concentration, in µg per mL, of USP Crotamiton RS in the Standard solution; and AU and AS are the absorbances of the assay solution and the Standard solution, respectively.

Expert Committee : (MDAA05) Monograph Development-Antivirals and Antimicrobials

USP29–NF24 Page 600

Phone Number : 1-301-816-8394