A: Evaporate a 1-mLportion to dryness:the residue so obtained meets the requirements for Identificationtest Aunder Metaraminol Bitartrate.

B: It meets the requirements for Identificationtests Band Cunder Metaraminol Bitartrate.

0.0032M Hexanesulfonate buffer— Mix 600mg of sodium 1-hexanesulfonate with water to obtain 1000mLof solution,adjust with phosphoric acid to a pHof 3.0±0.05,and filter.

Mobile phase— Prepare a suitable degassed and filtered mixture of methanol and 0.0032M Hexanesulfonate buffer(7:3).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Metaraminol Bitartrate RSin water to obtain a solution having a known concentration of about 0.2mg of metaraminol per mL.

Assay preparation— Transfer an accurately measured volume of Injection,equivalent to about 20mg of metaraminol,to a 100-mLvolumetric flask,dilute with water to volume,and mix.

System suitability preparation— Prepare a solution of propylparaben in alcohol containing 0.4mg per mL.Mix 1volume of this solution with 99volumes of the Standard preparation.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 264-nm detector and a 4-mm ×25-cm column that contains packing L7.The flow rate is about 1mLper minute.Chromatograph the System suitability preparationand the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency is not less than 2600theoretical plates,the resolution,R,between the metaraminol bitartrate and propylparaben peaks is not less than 3.0with propylparaben eluting first,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 metaraminol (C9H13NO2)in each mLof the Injection taken by the formula: in which Cis the concentration,in mg per mL,of metaraminol represented by the USP Metaraminol Bitartrate RSin the Standard preparation;Vis the volume,in mL,of Injection taken;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.