(dye'' en es' trol).
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C18H18O2 266.33

Phenol, 4,4¢-(1,2-diethylidene-1,2-ethanediyl)bis-, (E,E)-.
(E,E)-4,4¢-(Diethylideneethylene)diphenol [84-17-3; 13029-44-2].
» Dienestrol contains not less than 98.0 percent and not more than 100.5 percent of C18H18O2, calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers.
USP Reference standards 11
USP Dienestrol RS Click to View Structure
B: Ultraviolet Absorption 197U
Solution: 5 µg per mL.
Medium: alcohol.
Absorptivities at 228 nm, calculated on the dried basis, do not differ by more than 3.0%.
C: To a solution of about 10 mg in 0.5 mL of alcohol add 1 mL of hydrochloric acid and about 50 mg of vanillin: a blue color is produced immediately, and it persists on dilution with water but disappears on the addition of alkali (distinction from diethylstilbestrol, which produces no color).
Melting range 741: between 227 and 234, but the range between beginning and end of melting does not exceed 3.
Loss on drying 731 Dry it at 105 for 2 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281: not more than 0.2%.
Mobile phase, Internal standard solution, and Standard preparation Prepare as directed in the Assay under Dienestrol Cream.
Assay preparation— Transfer about 25 mg of Dienestrol, accurately weighed, to a 100-mL volumetric flask. Add methanol to volume, and mix. Pipet 2 mL of this solution, 5 mL of Internal standard solution, and 5 mL of water into a 50-mL volumetric flask. Dilute with methanol to volume, and mix.
Procedure— Proceed as directed for Procedure in the Assay under Dienestrol Cream. Calculate the quantity, in mg, of C18H18O2 in the portion of Dienestrol taken by the formula:
2.5C(RU / RS).
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Domenick Vicchio, Ph.D.
Senior Scientific Liaison
(SM42010) Monographs - Small Molecules 4
Reference Standards RS Technical Services
USP35–NF30 Page 2891