A: Infrared Absorption 197K.

B: Dissolve 1 g of Choline Bitartrate with 20 mL of water, and add 2 mL of potassium chloride solution (1 in 4). A white precipitate of potassium bitartrate is formed.

Test solution: 400 mg per mL, in water.

Test solution— Transfer 10.0 g of Choline Bitartrate to a beaker containing a plastic-coated stirring bar, add 70 mL of sodium hydroxide TS and 130 mL of water, and stir until dissolved.

Buffer solution, Mobile phase, Standard solution, and Chromatographic system— Proceed as directed in the test for Chromatographic purity under Choline Chloride.

Test solution— Transfer about 500 mg of Choline Bitartrate, accurately weighed, to a centrifuge tube; add 2.0 mL of water; and swirl to dissolve. Add 0.5 mL of potassium chloride solution (7.5 in 25), centrifuge, and transfer 1.0 mL of the supernatant to a 24-mL screw-capped vial. Dry at 120 for 2 hours. Add 400 mg of 3,5-dinitrobenzoyl chloride and 10 mL of acetonitrile, and mix. Cap the vial, and heat at 55 for 2 hours. Cool to room temperature, add 5 mL of water, and allow to stand for 5 minutes. Quantitatively transfer this solution to a 50-mL volumetric flask, dilute with Mobile phase to volume, and mix. Pipet 2.0 mL of the solution to a 25-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure all the peak responses. Calculate the percentage of each impurity in the portion of Choline Bitartrate taken by the formula: in which 253.25 and 139.62 are the molecular weights of choline bitartrate and choline chloride, respectively; C is the concentration of USP Choline Chloride RS, in mg per mL, in the Standard solution; W is the weight, in mg, of Choline Bitartrate taken to prepare the Test solution; ri is the peak response for each impurity, other than that of the choline bitartrate derivative and 3,5-dinitrobenzoic acid; and rS is the peak response for the choline chloride derivative in the Standard solution: not more than 0.3% of any individual impurity is found; and not more than 2.0% of total impurities is found.