A: It responds to the Identification test under Dextrose.

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 for dopamine hydrochloride.

Diluting solution— Prepare a solution containing approximately 0.022 N sodium hydroxide in water.

Cation-exchange column— Proceed as directed under Column Partition Chromatography (see Chromatography 621), using a chromatographic tube capable of providing a 0.8-cm × 4-cm bed volume (or about 2 mL) of 100- to 200-mesh, strongly acidic, styrene-divinylbenzene cation-exchange resin. Condition the column by washing with about 30 mL of water, discarding the eluate.

Procedure— Pass a volume of Injection containing about 100 mg of hydrous dextrose through the resin bed in the Cation-exchange column, allowing the specimen to flow down the wall of the column so as not to disturb the resin bed, and collect the eluate in a 50-mL volumetric flask. Wash the column with 25 mL of water, and collect the eluate in the same 50-mL volumetric flask. Dilute the eluate with Diluting solution to volume, and mix to obtain the test solution. In a similar manner, prepare a blank by passing 27 mL of water through a freshly conditioned Cation-exchange column, collecting the eluate in a 50-mL volumetric flask, diluting with Diluting solution to volume, and mixing. Determine the absorbance of the test solution against the blank in a 1-cm cell at 284 nm, with a suitable spectrophotometer: the absorbance is not more than 0.25.

(100/52.9)(198.17/180.16)AR