A: Ultraviolet Absorption á197Uñ—

B: 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.

Buffer solution,Mobile phase,and Diluent— Proceed as directed for Test 1in the Chromatographic puritytest under Gadoteridol.

Standard solution— Prepare a solution of gadolinium (Gd III)acetate in water to obtain a solution having a known concentration of about 0.4mg of gadolinium acetate per mL.Transfer 1.0mLof the solution to a 10-mLvolumetric flask,dilute with Diluentto volume,and mix.Transfer 1.0mLof this solution to a small vial,add 3.0mLof Diluent,and mix.

Test solution— Transfer an accurately measured volume of Injection,equivalent to about 150mg of gadoteridol,to a small vial,dilute with Diluentto 5.0mL,and mix.Immediately place in a bath maintained at about 5.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a fluorometric detector operating at an excitation wavelength of 275nm and an emission wavelength of 314nm and a 4.6-mm ×25-cm column that contains 5-µm packing L1.The flow rate is about 1mLper minute.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the relative standard deviation for replicate injections is not more than 5.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms for about 1.5times the retention time of the gadoteridol peak,and measure the peak responses.Calculate the percentage,by weight,of free gadolinium (III)in the volume of Injection taken by the formula: in which 157.25and 334.38are the molecular weights of gadolinium and gadolinium acetate,respectively;Cis the concentration,in mg per mL,of gadolinium (Gd III)acetate,calculated on the anhydrous basis,in the Standard solution;Vis the volume,in mL,of Injection taken for the Test solution;Pis the labeled potency of gadoteridol,in mg per mL,in the Injection;and rUand rSare the peak responses for free gadolinium (III)obtained from the Test solutionand the Standard solution,respectively:not more than 0.02%is found.

Buffer solution,Mobile phase,Cupric acetate solution,Standard stock solution,Standard solution,and Chromatographic system— Proceed as directed for the Limit of gadoteridol related compound Atest under Gadoteridol.

Test solution— Transfer an accurately measured volume of Injection,equivalent to about 30mg of gadoteridol,to a test tube,dilute with chilled Buffer solutionto 1.0mL,and mix.Add 1.0mLof chilled Cupric acetate solution,mix on a vortex mixer for about 10seconds,and immediately inject as directed for Procedure.

Procedure— Separately inject equal volumes (about 50µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the peak responses.Calculate the percentage of gadoteridol related compound Ain the Injection by the formula: in which Cis the concentration,in µg per mL,of USP Gadoteridol Related Compound A RSin the Standard solution;Vis the volume,in mL,of Injection taken for the Test solution;Pis the labeled potency,in mg per mL,of gadoteridol in the Injection;and rUand rSare the peak responses of gadoteridol related compound Ain the Test solutionand the Standard solution,respectively:not more than 0.02%is found.

Buffer solution,Mobile phase,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Gadoteridol.

Assay preparation— Transfer an accurately measured volume of Injection,equivalent to about 150mg of gadoteridol,to a 250-mLvolumetric flask,dilute with Buffer solutionto volume,and mix.

Procedure— Separately inject equal volumes (about 20µL)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 per mL,of gadoteridol (C17H29GdN4O7)in the volume of Injection taken by the formula: in which Cis the concentration,in mg per mL,of USP Gadoteridol RSin the Standard preparation;Vis the volume of Injection taken,in mL;and rUand rSare the gadoteridol peak responses obtained from the Assay preparationand the Standard preparation,respectively.