Adsorbent, Application volume, Developing solvent system, and Spray reagent— Proceed as directed for Related compounds, Test 1 under Pamidronate Disodium.

Standard solution— Dissolve an accurately weighed quantity of USP Beta Alanine RS in water, and dilute quantitatively, and stepwise if necessary, with water to obtain a solution containing 0.0075 mg of beta alanine per mL.

Test solution— Reconstitute the vial with the appropriate amount of water to obtain a solution having a concentration of 3 mg of anhydrous pamidronate disodium per mL, based on the label claim.

Procedure— Proceed as directed for Thin-Layer Chromatography under Chromatography 621. Dry the plate between 100 and 105 until the ammonia disappears completely. Spray with Spray reagent, and heat between 100 and 105 for about 15 minutes. Examine the plate under white light. The spot having an RF value of about 0.5 obtained from the Test solution is not greater in size or intensity than the corresponding spot obtained from the Standard solution: not more than 0.25% of beta alanine is found.

Mobile phase and Chromatographic system— Proceed as directed in the Assay under Pamidronate Disodium.

Standard preparation— Dissolve an accurately weighed quantity of USP Pamidronate Disodium RS in water, and dilute quantitatively, and stepwise if necessary, with water to obtain a solution having a known concentration of about 2.5 mg per mL. Calculate the concentration, Cs, of anhydrous pamidronate disodium, the molecular weights of anhydrous and pentahydrate pamidronate disodium being 279.06 and 369.11, respectively.

Assay preparation— Constitute a suitable number of vials of Pamidronate Disodium for Injection with the appropriate amount of water to obtain a solution having a known concentration of about 2 mg of anhydrous pamidronate disodium per mL, based on the label claim.

Procedure— Separately inject equal volumes (about 100 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the percentage of C3H9NNa2O7P2 in the portion of Pamidronate Disodium for Injection taken by the formula: in which CS is as defined under the Standard preparation; CU is the concentration, in mg per mL, of anhydrous pamidronate disodium in the Assay preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.