Ethanol, 2,2
¢,2
¢¢,2
¢¢¢-[4,8-di-1-piperidinylpyrimido[5,4-
d]pyrimidine-2,6-diyl)dinitrilo]tetrakis-.
2,2
¢,2
¢¢,2
¢¢¢-[4,8-Dipiperidinopyrimido[5,4-
d]pyrimidine-2,6-diyl)dinitrilo]tetraethanol
[
58-32-2].
Packaging and storage—
Preserve in tight, light-resistant containers. Store at room temperature.
Melting range 
741
:
between 162
and 168
, but the range between beginning and end of melting does not exceed 2
.
Chloride—
Dissolve 500 mg in 5 mL of alcohol and 2 mL of 2 N nitric acid, and add 1 mL of
silver nitrate TS: no turbidity or precipitate is produced.
Heavy metals, Method II 231:
0.001%.
Organic volatile impurities, Method IV 467:
meets the requirements.
Chromatographic purity—
Mobile phase and Chromatographic system—
Prepare as directed in the
Assay under
Dipyridamole Tablets.
Test preparation A—
Prepare a solution of Dipyridamole in methanol having a known concentration of 1 mg per mL.
Test preparation B—
Dilute 1.0 mL of Test preparation A with methanol to 100 mL, and mix.
Procedure—
Inject 10 µL of Test preparation B into the chromatograph by means of a sampling valve, adjusting the operating parameters so that the response of the main peak (retention time about 6.5 minutes) obtained is about 5% full scale. Inject 10 µL of Test preparation A, and run the chromatograph for 10 minutes: the sum of responses of all secondary peaks obtained from Test preparation A is not greater than the response of the main peak obtained from Test preparation B (1.0%).
Assay—
Transfer about 450 mg of Dipyridamole, accurately weighed, to a 250-mL beaker, and dissolve in 50 mL of glacial acetic acid. Stir for 30 minutes. Add 75 mL of acetone, and stir for an additional 15 minutes. Titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically, using a glass electrode and a silver-silver chloride reference electrode system. Perform a blank titration, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 50.46 mg of C24H40N8O4.
;)