Standard solution— Transfer 2.0mLof 0.100Niodine VSto a 500-mLvolumetric flask,dilute with water to volume,and mix.

Procedure— Visually examine a portion of the Inhalation Solution (Test solution)in a suitable clear glass test tube against a white background:it is not pinkish and it contains no precipitate.If any yellow color is observed in the Test solution,concomitantly determine the absorbances of the Test solutionand the Standard solutionin 1-cm cells with a suitable spectrophotometer set at 460nm:the absorbance of the Test solutiondoes not exceed that of the Standard solution.

Mobile phase— Prepare a filtered and degassed mixture of 0.05Mmonobasic sodium phosphate and methanol (85:15).Dissolve a suitable quantity of sodium 1-octanesulfonate in this mixture to obtain a solution that is 0.005Mwith respect to sodium 1-octanesulfonate.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Epinephrine Bitartrate RSin a mixture of 0.05Mmonobasic sodium phosphate and methanol (85:15),and dilute quantitatively,and stepwise if necessary,with the same solvent mixture to obtain a solution having a known concentration of about 0.1mg per mL.

Assay preparation— Transfer an accurately measured volume of Inhalation Solution,equivalent to about 11mg of racepinephrine,to a 200-mLvolumetric flask,dilute with a mixture of 0.05Mmonobasic sodium phosphate and methanol (85:15)to volume,and mix.

System suitability preparation— Dissolve a suitable quantity of dopamine hydrochloride in a mixture of 0.05Mmonobasic sodium phosphate and methanol (85:15)to obtain a solution containing about 0.1mg per mL.Transfer 20.0mLof this solution to a 50-mLvolumetric flask.Add 5.0mLof the Standard preparation,dilute with a mixture of 0.05Mmonobasic sodium phosphate and methanol (85:15)to volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 280-nm detector and a 4.6-mm ×25-cm column that contains 5-µm packing L1.The flow rate is about 1mLper minute.Chromatograph the Standard preparationand the System suitability preparation,and record the peak responses as directed for Procedure:the tailing factor for the analyte peak is not more than 1.2,the resolution,R,between the dopamine and analyte peak is not less than 5.0,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C9H13NO3in each mLof the Inhalation Solution taken by the formula: in which 183.20and 333.29are the molecular weights of racepinephrine and epinephrine bitartrate,respectively;Cis the concentration,in mg per mL,of USP Epinephrine Bitartrate RSin the Standard preparation;Vis the volume,in mL,of Inhalation Solution taken;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.