Medium: pH 6.8 Phosphate buffer (see Buffer Solutions under Solutions in the section Reagents, Indicators, and Solutions); 900 mL.

Apparatus 1: 100 rpm.

Time: 30 minutes.

pH 6.8 Phosphate buffer, Mobile phase, and Chromatographic system— Proceed as directed in the Assay.

Standard solution— Quantitatively dissolve an accurately weighed quantity of USP Cycloserine RS in pH 6.8 Phosphate buffer to obtain a solution having a known concentration of about 0.25 mg per mL.

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

Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into 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 C is the concentration, in mg per mL, of USP Cycloserine RS in the Standard solution; and rU and rS are 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 C3H6N2O2 is dissolved in 30 minutes.

pH 6.8 Phosphate buffer, Mobile phase, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Cycloserine.

Assay preparation— Remove, as completely as possible, the contents of not fewer than 20 Capsules. Transfer an accurately weighed portion of the powder, equivalent to about 100 mg of cycloserine, to a 250-mL volumetric flask, dilute with pH 6.8 Phosphate buffer to volume, mix, and filter.

Procedure— Proceed as directed in the Assay under 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.