A: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.

B: It meets the requirements of the tests for Manganese á191ñ.

Phosphate buffer and Mobile phase— Proceed as directed in the Assayunder Mangafodipir Trisodium.

Standard preparation— Prepare a solution of USP Mangafodipir Trisodium RSin water having a known concentration of about 2mg per mL.Transfer 10.0mLof this solution to a 50-mLvolumetric flask,add 5.0mLof Phosphate buffer,dilute with water to volume,and mix.[NOTE—Store under nitrogen to avoid excessive exposure to air and light.]

Assay preparation— Transfer an accurately measured volume of Injection,equivalent to about 100mg of mangafodipir trisodium,to a 50-mLvolumetric flask,dilute with water to volume,and mix.Transfer 10.0mLof this solution to a 50-mLvolumetric flask,add 5.0mLof Phosphate buffer,dilute with water to volume,and mix.[NOTE—Store under nitrogen to avoid excessive exposure to air and light.]

Chromatographic system— Prepare as directed in the Assayunder Mangafodipir Trisodium.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency is not less than 1000theoretical plates;and the tailing factor is not more than 2.3.

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 mangafodipir trisodium (C22H27MnN4Na3O14P2)in each mLof the Injection taken by the formula: in which Cis the concentration,in mg per mL,of USP Mangafodipir Trisodium RSin the Standard preparation;Vis the volume,in mL,of Injection taken to prepare the Assay preparation;and rUand rSare the mangafodipir peak responses obtained from the Assay preparationand the Standard preparation,respectively.