A: Radionuclidic identity—Its half-life, determined using a suitable detector system (see Radioactivity 821 is between 9.5 and 10.5 minutes.

B: Radiochemical identity—The retention time of the major peak in the chromatogram of the Test solution corresponds to that in the chromatogram of the Standard solution, as obtained in the Radiochemical purity test.

Mobile phase— Add 0.25 mL of concentrated nitric acid to 1000 mL of a mixture of water and methanol (7:3), filter, and degas.

Standard solution— Dissolve an accurately weighed quantity of USP Ammonium Chloride RS in water, and dilute quantitatively, and stepwise if necessary, with water to obtain a solution having a known concentration of about 0.1 mg per mL.

Test solution— Use the Injection.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 4.1-mm × 25-cm column that contains 10-µm packing L17. It is equipped with a gamma ray detector and a conductivity detector. The flow rate is about 2.0 mL per minute. Chromatograph the Test solution, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 5%.

Procedure— Prepare a mixture of the Standard solution and the Test solution (1:1), and inject about 20 µL of the mixture into the chromatograph, record the chromatograms, and measure the peak areas. The areas of both the main radioactive and nonradioactive peaks are equal. [note—The volume of Injection may be adjusted to obtain suitable detection system sensitivity.] The radioactivity of the major peak is not less than 95% of the total radioactivity measured. The retention time of the Test solution corresponds to the retention time of the Standard solution.

aluminum (to be determined if Devarda's alloy is used to reduce 13N nitrate/nitrite)—

Aluminum standard solution— Transfer 35.17 mg of aluminum potassium sulfate dodecahydrate, accurately weighed, to a 1000-mL volumetric flask, and dilute with water to volume to obtain a solution having a known concentration of 2 µg of aluminum per mL.

Procedure— Pipet 10 mL of Aluminum standard solution into each of two 50-mL volumetric flasks. To each flask add 3 drops of methyl orange TS and 2 drops of 6 N ammonium hydroxide, then add 0.5 N hydrochloric acid, dropwise, until the solution turns red. To one flask add 25 mL of sodium thioglycolate TS, and to the other flask add 1 mL of edetate disodium TS. To each flask add 5 mL of eriochrome cyanine TS and 5 mL of acetate buffer TS, and add water to volume. Immediately determine the absorbance of the solution containing sodium thioglycolate TS at the wavelength of maximum absorbance at about 535 nm, with a suitable spectrophotometer, using the solution containing the edetate disodium TS as a blank. Repeat the procedure using two 1.0-mL aliquots of Injection. Calculate the quantity, in µg per mL, of aluminum in the Injection taken by the formula: in which TU and TS are the absorbances of the solutions from the Injection and the Aluminum standard solution, respectively. The concentration of aluminum ion in the Injection is not greater than 10 µg per mL.