Assay
Diluent
Prepare a mixture of water and methanol (1:1).
Mobile phase
Prepare a suitable mixture of water,acetonitrile,and methanol (60:20:20)containing 0.06%of sulfuric acid,0.5%of sodium sulfate,and 0.02%of sodium 1-heptanesulfonate.The pHis about 2.6.Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Standard preparation
Dissolve an accurately weighed quantity of
USP Tetracaine Hydrochloride RSquantitatively in
Diluentto obtain a solution having a known concentration of about 1mg per mL.
Resolution solution
Dissolve a quantity of salicylic acid in a portion of the Standard preparationto obtain a solution containing about 4mg of salicylic acid and 1mg of tetracaine hydrochloride per mL.
Assay preparation
Transfer an accurately measured volume of Injection equivalent to about 50mg of tetracaine hydrochloride,to a 50-mLvolumetric flask,dilute with Diluentto volume,and mix.
Chromatographic system
(see
Chromatography á621ñ)The liquid chromatograph is equipped with a 305-nm detector and a 3.9-mm ×30-cm column containing packing L1.The flow rate is about 2mLper minute.Chromatograph the
Resolution solution,and record the responses as directed for
Procedure:the relative retention times are about 0.8for salicylic acid and 1.0for tetracaine;and the resolution,
R,between the salicylic acid peak and the tetracaine peak is not less than 2.Chromatograph the
Standard preparation,and record the responses as directed for
Procedure:the relative standard deviation for replicate injections is not more than 2.0%.
Procedure
Separately inject equal volumes (about 5µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of tetracaine hydrochloride (C
15H
24N
2O
2·HCl)in each mLof the Injection taken by the formula:
50(C/V)(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Tetracaine Hydrochloride RSin the
Standard preparation;Vis the volume,in mL,of Injection taken;and
rUand
rSare the tetracaine peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.