A: Transfer a volume of Oral Solution, equivalent to about 100 mg of saccharin, to a small dish, evaporate to dryness, and gently fuse the residue over a small flame until it no longer evolves ammonia. Allow the residue to cool, dissolve in 20 mL of water, neutralize the solution with 3 N hydrochloric acid, and filter: the addition of 1 drop of ferric chloride TS to the filtrate produces a violet color.

B: It responds to the tests for Sodium 191.

(Official January 1, 2007)

Mobile phase— Mix 5 mL of 10 percent tetramethylammonium hydroxide solution and 400 mL of water in a 500-mL volumetric flask, adjust with phosphoric acid to a pH of 4.0, and mix. Add 50 mL of methanol to the solution, dilute with water to volume, mix, and degas the solution.

Standard preparation— Add to an accurately weighed quantity of USP Saccharin RS an amount of 0.1 N sodium hydroxide sufficient to dissolve the solid, and dilute quantitatively with water to obtain a solution having a known concentration of about 1.2 mg of saccharin per mL.

Assay preparation— Transfer an accurately measured volume of Oral Solution, equivalent to about 120 mg of saccharin, to a 100-mL volumetric flask, dilute with water to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 257-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph three replicate injections of the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph using a suitable microsyringe or sampling valve, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of saccharin (C7H5NO3S) in each mL of the Oral Solution taken by the formula: in which C is the concentration, in mg per mL, of USP Saccharin RS in the Standard preparation, V is the volume, in mL, of Oral Solution taken, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.