A: It yields a white precipitate with mercuric chloride TS, and a red-brown precipitate with iodine TS. It also yields a precipitate with mercuric-potassium iodide TS, and with trinitrophenol TS.

B: Dilute a portion of Injection with water to a concentration of about 10 mg of thiamine hydrochloride per mL. To 0.5 mL of this solution add 5 mL of 0.5 N sodium hydroxide, then add 0.5 mL of potassium ferricyanide TS and 5 mL of isobutyl alcohol, shake the mixture vigorously for 2 minutes, and allow the liquid layers to separate: when illuminated from above by a vertical beam of UV light and viewed at a right angle to this beam, the air-liquid meniscus shows a vivid blue fluorescence, which disappears when the mixture is slightly acidified, but reappears when it is again made alkaline.

C: It responds to the tests for Chloride 191.

(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 Injection with Mobile phase to obtain a solution containing about 500 µg of thiamine hydrochloride 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 hydrochloride (C12H17ClN4OS·HCl) in each mL of the Injection taken by the formula: in which 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 hydrochloride in the Injection; D is the concentration, in mg per mL, of thisamine hydrochloride 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.