Assay preparation
Transfer to a tared 20-mLbeaker the contents of a sufficient number of containers of Tetracaine Hydrochloride for Injection to yield about 100mg of tetracaine hydrochloride.Weigh immediately,and transfer with the aid of water to a 500-mLvolumetric flask.Add water to volume,and mix.Transfer 5.0mLto a 100-mLvolumetric flask,add 5mLof dilute hydrochloric acid (1in 200)and 10mLof
Buffer No.6,10percent,pH6.0(see
Phosphate Buffers á81ñ),then add water to volume,and mix.
Procedure
Concomitantly determine the absorbances of the
Assay preparationand the
Standard preparationat the wavelength of maximum absorbance at about 310nm,with a suitable spectrophotometer,using water as the blank.Calculate the quantity,in mg,of C
15H
24N
2O
2·HCl in the portion of Tetracaine Hydrochloride for Injection taken by the formula:
10C(AU/AS),
in which
Cis the concentration,in µg per mL,of
USP Tetracaine Hydrochloride RSin the
Standard preparation,and
AUand
ASare the absorbances of the
Assay preparationand the
Standard preparation,respectively.