Medium: water; 900 mL.

Apparatus 2: 75 rpm.

Time: 30 minutes.

Standard preparation— Dissolve an accurately weighed quantity of USP Ampicillin RS in water to obtain a solution having a known concentration of about 0.3 mg per mL.

Procedure— Determine the amount of ampicillin (C16H19N3O4S) dissolved as directed for Procedure in the section Antibiotics—Hydroxylamine Assay under Automated Methods of Analysis 16.

Tolerances— Not less than 85% (Q) of the labeled amount of C16H19N3O4S is dissolved in 30 minutes.

Mobile phase, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Bacampicillin Hydrochloride.

Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 56 mg of ampicillin (C16H19N3O4S), to a 100-mL volumetric flask, add 90 mL of water, and sonicate for about 20 minutes. Dilute with water to volume, mix, and filter through a filter of 0.5-µm or finer porosity.

Procedure— Proceed as directed for Procedure in the Assay under Bacampicillin Hydrochloride. Calculate the quantity, in mg, of ampicillin (C16H19N3O4S) equivalent to the portion of Tablets taken by the formula: in which the terms are as defined therein.