A: It responds to Identificationtest Bunder Thiamine Hydrochloride Injection.

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

Mobile phase,Internal standard solution,Standard preparation,andChromatographic system— Prepare as directed in the Assayunder Thiamine Hydrochloride Elixir.

Assay preparation— Dilute an accurately measured volume of Elixir quantitatively with Mobile phaseto obtain a solution containing about 500µg of thiamine mononitrate per mL.Pipet 10mLof the resulting solution and 10mLof Internal standard solutioninto a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Procedure— Proceed as directed for Procedurein the Assayunder Thiamine Hydrochloride Elixir.Calculate the quantity,in mg,of C12H17N5O4Sin each mLof the Elixir taken by the formula: in which 327.36and 337.27are the molecular weights of thiamine mononitrate and thiamine hydrochloride,respectively;Cis the concentration,in mg per mL,of USP Thiamine Hydrochloride RSin the Standard preparation;Lis the labeled quantity,in mg per mL,of thiamine mononitrate in the Elixir;Dis the concentration,in mg per mL,of thiamine mononitrate in the Assay preparationon the basis of the labeled quantity and the extent of dilution;and RUand RSare the ratios of the peak responses of thiamine to methylparaben obtained from the Assay preparationand the Standard preparation,respectively.