Spray reagent— Add 5.6 g of stannous chloride to 10 mL of hydrochloric acid, and stir for 5 minutes. [note—It is not necessary that all of the solids dissolve.] Add 90 mL of water and 1 g of potassium iodide, and stir. Prepare this solution fresh daily.

Standard solution— Prepare a solution in water containing 10 mg of USP Carboplatin RS per mL.

Test solution— Dissolve the contents of 1 container in water to obtain a solution containing 10 mg of carboplatin per mL.

Procedure— Separately apply 10 µL each of the Standard solution and the Test solution to a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel. Place the plate in a chromatographic chamber lined with filter paper and equilibrated for 2 hours with a mixture of acetone and water (80:20). Develop the chromatogram until the solvent front has moved about 10 cm from the origin. Remove the plate from the chamber, and air-dry at room temperature for 2 hours. Spray with the Spray reagent, and heat at 110 for 10 minutes: the principal spot from the Test solution corresponds in appearance and RF value to that obtained from the Standard solution.

Mobile phase , System suitability solution, and Chromatographic system—Proceed as directed for Limit of 1,1-cyclobutanedicarboxylic acid under Carboplatin.

Standard solution— Dissolve an accurately weighed quantity of 1,1-cyclobutanedicarboxylic acid in Mobile phase to obtain a solution having a known concentration of about 0.5 mg per mL. Transfer 2.0 mL of this solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Test solution— Quantitatively dissolve the contents of 1 container in Mobile phase to obtain a solution having a concentration of 1 mg of carboplatin per mL. [note—Complete the chromatographic analysis of the solution within 2 hours.]

Procedure— Separately inject equal volumes (about 100 µL) of the Test solution and the Standard solution into the chromatograph, record the chromatograms, and measure the responses for the 1,1-cyclobutanedicarboxylic acid peaks. Calculate the percentage of 1,1-cyclobutanedicarboxylic acid in the portion of Carboplatin for Injection taken by the formula: in which C is the concentration, in mg per mL, of 1,1-cyclobutanedicarboxylic acid in the Standard solution; V is the volume, in mL, of the constituted container contents; L is the labeled quantity, in mg, of carboplatin per container; and rU and rS are the peak responses for 1,1-cyclobutanedicarboxylic acid obtained from the Test solution and the Standard solution, respectively: not more than 1.0% is found.

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

Assay preparation— Quantitatively dissolve the contents of 1 container in water to obtain a solution having a concentration of 1 mg per mL. [note—Complete chromatographic analysis of this solution within 2 hours.]

Procedure— Separately inject equal volumes (about 10 µL) of the Assay preparation and the Standard preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C6H12N2O4Pt in the portion of Carboplatin for Injection taken by the formula: in which C is the concentration, in mg per mL, of USP Carboplatin RS in the Standard preparation; V is the volume, in mL, of the constituted container contents; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.