Medium: pH6.8Phosphate buffer(see Buffer Solutionsunder Solutionsin the section Reagents,Indicators,and Solutions);900mL.

Apparatus 1: 100rpm.

Time: 30minutes.

pH6.8Phosphate buffer,Mobile phase,and Chromatographic system— Proceed as directed in the Assay.

Standard solution— Quantitatively dissolve an accurately weighed quantity of USP Cycloserine RSin pH6.8Phosphate bufferto obtain a solution having a known concentration of about 0.25mg per mL.

Test solution— Use a filtered portion of the solution under test.

Procedure— Separately inject equal volumes (about 10µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the peak responses for cycloserine.Calculate the quantity,in mg,of cycloserine (C3H6N2O2)dissolved by the formula: in which Cis the concentration,in mg per mL,of USP Cycloserine RSin the Standard solution;and rUand rSare the peak responses for cycloserine obtained from the Test solution and the Standard solution,respectively.

Tolerances— Not less than 80%(Q)of the labeled amount of C3H6N2O2is dissolved in 30minutes.

pH6.8Phosphate buffer,Mobile phase,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Cycloserine.

Assay preparation— Remove,as completely as possible,the contents of not fewer than 20Capsules.Transfer an accurately weighed portion of the powder,equivalent to about 100mg of cycloserine,to a 250-mLvolumetric flask,dilute with pH6.8Phosphate bufferto volume,mix,and filter.

Procedure— Proceed as directed in the Assayunder Cycloserine.Calculate the quantity,in mg,of cycloserine (C3H6N2O2)in the portion of Capsules taken by the formula: in which the terms are as defined therein.