Uracil, C4H4N2O2112.09 [66-22-8]White to cream-colored, crystalline powder. Melts above 300. One g dissolves in about 500 mL of water; less soluble in alcohol; soluble in ammonia TS and in sodium hydroxide TS. Its solutions yield no precipitate with the usual alkaloidal precipitants.
Residue on ignition (Reagent test): negligible, from 100 mg.
Loss on drying 731 Dry it at 105 for 2 hours: it loses not more than 2% of its weight.
Uranyl Acetate (Uranium Acetate), UO2(C2H3O2)2·2H2O424.15 [541-09-3]Use ACS reagent grade.
Urea, NH2CONH260.06 [57-13-6]Use ACS reagent grade.
Urethane (Ethyl carbamate), C3H7NO289.09 [51-79-6]White powder with chunks. Freely soluble in water.
Melting range 741: between 48 and 50.
Uridine, C9H12N2O6244.20 [58-96-8]White powder.
mobile phase Prepare a mixture of methanol and 0.2 M ammonium acetate (90:10), and adjust with phosphoric acid to a pH of 7.0.
test solution: 0.5 mg per mL.
procedure Inject about 20 µL of the Test solution into a liquid chromatograph (see Chromatography 621), equipped with a 280-nm detector and a 4.6-mm × 15-cm column that contains packing L1. The flow rate is about 2.0 mL per minute. The area of the C9H12N2O6 peak is not less than 99% of the total peak area.
Melting range 741: between 166 and 171.