Internal standard solution , Standard preparation, and Chromatographic system—Prepare as directed in the Assay under Spectinomycin Hydrochloride.

Assay preparation 1— Suspend the contents of 1 container of Spectinomycin for Injectable Suspension in water, and dilute quantitatively with water to obtain a stock solution containing about 20 mg of spectinomycin per mL. Transfer 1.0 mL of this solution to a glass-stoppered, 25-mL conical flask, and freeze-dry. Add 10.0 mL of Internal standard solution and 1.0 mL of hexamethyldisilazane, and shake intermittently for 1 hour.

Assay preparation 2 (where the label states the quantity of spectinomycin in a given volume of constituted suspension)—Constitute 1 container of Spectinomycin for Injectable Suspension in a volume of water, accurately measured, corresponding to the volume of diluent specified in the labeling. Dilute an accurately measured portion of the constituted suspension quantitatively with water to obtain a stock solution containing about 20 mg of spectinomycin per mL. Transfer 1.0 mL of this solution to a glass-stoppered, 25-mL conical flask, and freeze-dry. Add 10.0 mL of Internal standard solution and 1.0 mL of hexamethyldisilazane, and shake intermittently for 1 hour.

Procedure— Proceed as directed in the Assay under Spectinomycin Hydrochloride. Calculate the quantity, in g, of C14H24N2O7 in the container of Spectinomycin for Injectable Suspension taken to prepare Assay preparation 1 taken by the formula: in which L1 is the labeled quantity, in g, of C14H24N2O7 in the container, and D1 is the concentration, in mg per mL, of spectinomycin in the stock solution used to prepare Assay preparation 1, on the basis of the labeled quantity in the container and the extent of dilution, and the other terms are as defined therein. Calculate the quantity, in mg, of C14H24N2O7 in each mL of constituted Injectable Suspension taken to prepare Assay preparation 2 taken by the formula: in which L2 is the labeled quantity, in mg, of C14H24N2O7 in each mL of constituted suspension of Spectinomycin for Injectable Suspension, and D2 is the concentration, in mg per mL, of spectinomycin in the stock solution used to prepare Assay preparation 2, on the basis of the labeled quantity in each mL of constituted suspension and the extent of dilution.