A: The IRabsorption spectrum of a potassium bromide dispersion of it exhibits maxima only at the same wavelengths as that of a similar preparation of USP Ritodrine Hydrochloride RS.

B: The retention time of the ritodrine hydrochloride in the Assay preparationobtained in the Assaycorresponds to that of the Standard preparationobtained in the Assay.

C: Asolution (1in 100)responds to the tests for Chloride á191ñ.

Mobile phaseand Chromatographic system— Prepare as directed in the Assay.

Test preparation— Prepare a solution containing about 1mg of Ritodrine Hydrochloride in each mLof Mobile phase.

Diluted test preparation— Quantitatively dilute a suitable volume of the Test preparationwith Mobile phaseto obtain a solution having a known concentration of 0.01mg per mLof ritodrine hydrochloride.

Procedure— Chromatograph the Test preparationand the Diluted test preparation,as directed in the Assay.The relative retention times are about 0.3for tyramine,0.65for erythro-1-(4-ketocyclohexyl)-2-[(1-hydroxyphenethyl)amino]propanol-1,0.85for erythro-p-hydroxy-[1-(4-ketocyclohexylethyl)amino]ethyl benzyl alcohol,1.0for ritodrine,1.15for threodiastereomer of ritodrine,and 2.3for p-hydroxy-b-(p-hydroxyphenethyl)amino]propiophenone.Determine the peak responses for ritodrine and for the related compounds from the chromatograms obtained from the Diluted test preparationand the Test preparation,respectively.Calculate the percentage of related compounds found:not more than 0.5%of any individual impurity and not more than 2.0%of total impurities is found.

Mobile phase— Dissolve 6.6g of dibasic ammonium phosphate and 1.1g of sodium 1-heptanesulfonate in 700mLof water,and mix with 300mLof methanol.Adjust by the addition of phosphoric acid to a pHof 3.0,mix,filter,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Ritodrine Hydrochloride RSin Mobile phaseto obtain a solution having a known concentration of about 0.2mg per mL.

Assay preparation— Transfer about 200mg of Ritodrine Hydrochloride,accurately weighed,to a 100-mLvolumetric flask,dissolve in Mobile phase,dilute with Mobile phaseto volume,and mix.Transfer 10.0mLof this solution to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

System suitability preparation— Dissolve about 20mg of Ritodrine Hydrochloride in about 50mLof Mobile phase.Add 5.6mLof sulfuric acid,dilute with Mobile phaseto 100mL,and mix.Heat a portion of this solution for about 2hours at about 85,and then cool to room temperature.Cautiously mix 10.0mLof the cooled solution with 8.0mLof sodium hydroxide solution (1in 10),and allow to cool.This solution contains ritodrine and its threodiastereomer.

Chromatographic system— The chromatograph is equipped with a 4.6-mm ×25-cm stainless steel column that contains packing L7and an UVdetector that monitors absorption at 214nm.Chromatograph about 50µLof the System suitability preparation:the resolution between ritodrine and its threodiastereomer is not less than 1.0.[NOTE—Chromatograms obtained as directed for this test,exhibit relative retention times of 1.0for ritodrine and approximately 1.2for the threo diastereomer.]

Procedure— Separately inject equal volumes (20to 50µL)of the Standard preparationand the Assay preparationinto the chromatograph (see Chromatography á621ñ)by means of a suitable sampling valve.Record the chromatograms and measure the peak responses.Calculate the quantity,in mg,of C17H21NO3·HCl in the portion of Ritodrine Hydrochloride taken by the formula: in which Cis the concentration,in mg per mL,of USP Ritodrine Hydrochloride RSin the Standard preparation;and rUand rSare the peak responses for Ritodrine Hydrochloride obtained from the Assay preparationand the Standard preparation,respectively.