A: Dilute a quantity of Lotion with acetone to obtain a solution having a concentration of benzoyl peroxide equivalent to 10mg per mL,and proceed with the solution so obtained as directed in the Identificationtest Aunder Hydrous Benzoyl Peroxide,beginning with “Apply 5µLof this solution.”The solution responds to the test.

B: It responds to the Identificationtest under Benzoyl Peroxide Gel.

Solution A,Solution B,Mobile phase,Standard preparation A,Standard preparation B,Standard preparation C,Standard preparation D,System suitability solution,and Chromatographic system— Proceed as directed in the test for Related compoundsunder Benzoyl Peroxide Gel.

Test preparation— Transfer an accurately weighed quantity of Lotion,equivalent to about 100mg of benzoyl peroxide,to a 50-mLvolumetric flask,add 25mLof acetonitrile,shake vigorously to disperse the specimen,sonicate for 5minutes,dilute with acetonitrile to volume,mix,and filter.

Procedure— Proceed with Lotion as directed for Procedurein the test for Related compoundsunder Benzoyl Peroxide Gel:it meets the limits stated.

Mobile phase ,Internal standard solution,Standard preparation,and Chromatographic system—Proceed as directed in the Assayunder Benzoyl Peroxide Gel.

Assay preparation— Prepare as directed for Assay preparationin the Assayunder Benzoyl Peroxide Gel,using Lotion.

Procedure— Proceed as directed for Procedurein the Assayunder Benzoyl Peroxide Gel.Calculate the quantity,in mg,of C14H10O4in the portion of Lotion taken by the formula: in which Cis the concentration,in mg per mL,of benzoyl peroxide in the Standard preparation;and RUand RSare the ratios of benzoyl peroxide peak response to ethyl benzoate peak response obtained from the Assay preparationand the Standard preparation,respectively.