Alkaline ascorbate reagent— Mix 100mLof alcohol,80mLof sodium hydroxide solution (1in 5),and 8mLof ascorbic acid solution (1in 50).Prepare fresh on the day of use.

Standard preparation— Place about 18mg of USP Epinephrine Bitartrate RS,accurately weighed,in a 100-mLvolumetric flask,add sodium bisulfite solution (1in 1000)to volume,and mix.Dilute this solution quantitatively with water to obtain a solution having a known concentration of about 10µg of epinephrine per mL.

Procedure— Pipet a volume of Injection,equivalent to about 10µg of epinephrine,into a 50-mLbeaker.Into another 50-mLbeaker pipet 1mLof Standard preparation.Treat the contents of each beaker as follows.Add 10mLof dilute hydrochloric acid (1in 120),and heat gently to reduce the volume of solution to about 5mL.Allow to cool to room temperature,then add 5mLof sodium acetate solution (1in 5),followed by 0.5mLof potassium ferricyanide solution (1in 400),and mix.At 2minutes,accurately timed,after the last addition,add 20mLof Alkaline ascorbate reagent,transfer the contents to a corresponding 50-mLvolumetric flask with the aid of water,add water to volume,and mix.At 15to 20minutes after the addition of the Alkaline ascorbate reagent,determine the fluorescences of each solution and of a reagent blank,with a suitable fluorometer,with an excitation wavelength setting of 420nm and a fluorescence wavelength setting of 520nm.Calculate the quantity,in µg,of C9H13NO3in each mLof Injection taken by the formula: in which Cis the concentration of epinephrine,in µg per mL,of USP Epinephrine Bitartrate RSin the Standard preparation,Vis the volume,in mL,of Injection taken,and IU,IS,and Bare the fluorescence readings of the solutions from the Injection,the Standard preparation,and the reagent blank,respectively.

Standard preparation— Transfer to a 125-mLseparator about 50mg,accurately weighed,of USP Procaine Hydrochloride RS,and dilute with water to 20mL.

Assay preparation— Transfer to a 125-mLseparator an accurately measured volume of Injection,equivalent to about 50mg of procaine hydrochloride,and dilute with water to 20mL.

Procedure— To the Standard preparationand also to the Assay preparationadd 5mLof 6Nammonium hydroxide,then treat each as follows.Extract with five 25-mLportions of chloroform,and filter the combined extracts through about 1g of anhydrous sodium sulfate supported on a pledget of glass wool.Receive the filtrate in a 200-mLvolumetric flask,add chloroform to volume,and mix.Transfer 3.0mLof this solution to a 100-mLvolumetric flask,add chloroform to volume,and mix.Concomitantly determine the absorbances of both solutions at the wavelength of maximum absorbance at about 280nm,with a suitable spectrophotometer,using chloroform as the blank.Calculate the quantity,in mg,of C13H20N2O2·HCl in each mLof the Injection taken by the formula: in which Wis the weight,in mg,of USP Procaine Hydrochloride RSused,Vis the volume,in mL,of Injection taken,and AUand ASare the absorbances of the solutions obtained from the Assay preparationand the Standard preparation,respectively.