A: It meets the requirements for Identification test B under Thiamine Hydrochloride Injection.

B: To 5 mL of Oral Solution add 2 mL of sulfuric acid, cool, and superimpose 2 mL of ferrous sulfate TS: a brown ring is produced at the junction of the two liquids.

(Official January 1, 2007)

Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system— Prepare as directed in the Assay under Thiamine Hydrochloride Oral Solution.

Assay preparation— Quantitatively dilute an accurately measured volume of Oral Solution with Mobile phase to obtain a solution containing about 500 µg of thiamine mononitrate per mL. Pipet 10 mL of the resulting solution and 10 mL of Internal standard solution into a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Procedure— Proceed as directed for Procedure in the Assay under Thiamine Hydrochloride Oral Solution. Calculate the quantity, in mg, of thiamine mononitrate (C12H17N5O4S) in each mL of the Oral Solution taken by the formula: in which 327.36 and 337.27 are the molecular weights of thiamine mononitrate and thiamine hydrochloride, respectively; C is the concentration, in mg per mL, of USP Thiamine Hydrochloride RS in the Standard preparation; L is the labeled quantity, in mg per mL, of thiamine mononitrate in the Oral Solution; D is the concentration, in mg per mL, of thiamine mononitrate in the Assay preparation on the basis of the labeled quantity and the extent of dilution; and RU and RS are the ratios of the peak responses of thiamine to methylparaben obtained from the Assay preparation and the Standard preparation, respectively.