Urea C14Capsules Click to View Image »Urea C14Capsules contain 14CH4N2Oin which a portion of the molecules are labeled with radioactive 14Cto provide 0.04MBq (or 1µCi)of radioactivity per capsule.It contains not less than 90.0percent and not more than 110.0percent of the labeled amount of 14Cexpressed as MBq (or µCi). Packaging and storage— Preserve in tight containers,and store at controlled room temperature. Expiration date— The expiration date is not later than two years from the date of manufacture. Labeling— Label it to include the following:the amount of 14C,expressed in MBq (or µCi)per Capsule at the time of calibration;the expiration date;the total radioactivity per container;and the statement,“Caution—Radioactive material.” Radionuclide identification á821ñ Asolution of 1or more Capsules in 1Nhydrochloric acid when tested using a liquid scintillation counter produces beta emission having a 49keVmean and a 156keVmax. Dissolution á711ñ Medium: simulated gastric fluid TS;500mL. Apparatus 1: 50rpm. Time: 10minutes. Procedure— Determine the background levels of 14Cwith a 1-mLportion of the solution under test using a liquid scintillation counter. Tolerances: not less than 80%(Q)of the labeled amount of 14Cis dissolved in 10minutes. Uniformity of dosage units á905ñ: meet the requirements. Radionuclidic purity á821ñ Determine the radionuclidic purity of a solution of 1or more Capsules in water using a liquid scintillation counter:not less than 99.9%of the radioactivity is present as C14. Radiochemical purity— Adsorbent: 0.25-mm layer of chromatographic cellulose. Test solution— Open 2Capsules and place them in a suitable container,add 8mLof methanol,and mix. Reference solution: 40mg of urea per mL,in water. Application volume: 20µLof the Test solutionand 4µLof the Reference solution. Developing solvent system: n-butanol saturated with water. Procedure— Proceed as directed for Thin-Layer Chromatographyunder Chromatography á621ñ.Locate the spots on the plate by spraying with Ehrlich's reagent.Determine the radioactivity distribution with a suitable radiation detector (see Radioactivity á821ñ),and obtain the RFvalue:the RFvalue of the principal spot from the Test solutioncorresponds to that obtained from the Reference solution,and the radioactivity of the 14Cband is not less than 90%of the total radioactivity. Assay for radioactivity á821ñ Prepare a solution of 1or more Capsules in 1Nhydrochloric acid.Using a liquid scintillation counter,determine the radioactivity,in MBq (or mCi)per mLby use of a calibrated system. Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate Expert Committee:(RMI)Radiopharmaceuticals and Medical Imaging Agents USP28–NF23Page 355 Pharmacopeial Forum:Volume No.27(2)Page 2126 Phone Number:1-301-816-8305