A: Ultraviolet Absorption 197U—

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

Mobile phase, Postcolumn reagent, System suitability solution, and Chromatographic system— Proceed as directed for Related compounds under Gadodiamide.

Test solution— Transfer an accurately measured volume of Injection, equivalent to about 200 mg of gadodiamide, to a 100-mL volumetric flask, dilute with water to volume, and mix.

Procedure— Inject about 10 µL of the Test solution into the chromatograph, record the chromatogram, and measure the peak responses. [note—The tail of the gadodiamide peak may contain a small shoulder due to an isomer; the area of the shoulder should be included in the gadodiamide peak area.] Calculate the percentage of each impurity in the volume of Injection taken by the formula: in which ri is the peak response of each impurity; and rs is the sum of all peaks having a percentage greater than 0.10%: not more than 2.0% of gadodiamide related compounds A and B is found; no individual impurity is more than 0.2%; and the sum of all impurities, other than gadodiamide related compounds A and B, is not more than 0.5%.

Mobile phase, Postcolumn reagent, and Chromatographic system— Proceed as directed in the Assay under Gadodiamide.

Standard preparation— Transfer about 60 mg of USP Gadodiamide RS, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Transfer 15.0 mL of this solution to a 100-mL volumetric flask, dilute with water to volume, and mix.

Assay preparation— Transfer an accurately measured volume of Injection, equivalent to about 574 mg of gadodiamide, to a 100-mL volumetric flask, dilute with water to volume, and mix. Transfer 3.0 mL of this solution to a 100-mL volumetric flask, dilute with water to volume, and mix.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of gadodiamide (C16H26GdN5O8) in each mL of the Injection taken by the formula: in which C is the concentration, in mg per mL, of USP Gadodiamide RS in the Standard preparation; V is the volume, in mL, of Injection taken; and rU and rS are the gadodiamide peak responses obtained from the Assay preparation and the Standard preparation, respectively.