Estrone
;)
Estra-1,3,5(10)-trien-17-one,3-hydroxy-.
3-Hydroxyestra-1,3,5(10)-trien-17-one [53-16-7].
»Estrone contains not less than 97.0percent and not more than 103.0percent of C18H22O2,calculated on the dried basis.
Packaging and storage—
Preserve in tight,light-resistant containers.Store at 25
,excursions permitted between 15and 30.
,excursions permitted between 15and 30.
Clarity of solution—
Add 100mg to 100mLof 1Nsodium hydroxide in a 125-mLconical flask,heat on a steam bath until solution is complete,then cool,and transfer to a 100-mLcolor-comparison tube:the solution is clear.
Identification—
A:Infrared Absorption á197Kñ.
B:Ultraviolet Absorption á197Uñ—
Solution:
50µg per mL.
Medium:
alcohol,heated on a steam bath and cooled to room temperature.
Specific rotation á781Sñ:
between +158and +165.
and +165.
Test solution:
10mg,previously dried,per mL,in dioxane.
Loss on drying á731ñ—
Dry it at 105for 3hours:it loses not more than 0.5%of its weight.
for 3hours:it loses not more than 0.5%of its weight.
Residue on ignition á281ñ:
not more than 0.5%.
Limit of equilenin and equilin—
Dissolve 10mg in sufficient alcohol to make 50mL.Transfer 5mLof the solution to a small beaker.Add 5mLof a buffer solution prepared by dissolving 2mLof glacial acetic acid and 13.3g of anhydrous sodium acetate in water to make 100mL,warm to about 50,and add 1mLof a freshly prepared 1in 200solution of 2,6-dibromoquinone-chlorimide in alcohol.Mix,and allow to stand for 30minutes.Transfer the solution to a small separator,add 10mLof chloroform and 20mLof 1Nsodium hydroxide,and shake vigorously for 2minutes.Separate the chloroform layer,and filter rapidly through a dry filter paper into a dry test tube,discarding the first 2mLof the filtrate.Viewed transversely against a white background,the chloroform filtrate shows no more red color than that produced by similarly treating 5mLof an alcohol solution containing 20µg of equilenin.
,and add 1mLof a freshly prepared 1in 200solution of 2,6-dibromoquinone-chlorimide in alcohol.Mix,and allow to stand for 30minutes.Transfer the solution to a small separator,add 10mLof chloroform and 20mLof 1Nsodium hydroxide,and shake vigorously for 2minutes.Separate the chloroform layer,and filter rapidly through a dry filter paper into a dry test tube,discarding the first 2mLof the filtrate.Viewed transversely against a white background,the chloroform filtrate shows no more red color than that produced by similarly treating 5mLof an alcohol solution containing 20µg of equilenin.
Ordinary impurities á466ñ—
Test solution:
acetone.
Standard solution:
acetone.
Eluant:
a mixture of chloroform and acetone (9:1),in a nonequilibrated chamber.
Visualization:
5.
Assay—
Mobile phase—
Prepare a filtered and degassed mixture of acetonitrile and 0.05Mmonobasic potassium phosphate (1:1).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Standard preparation—
Transfer about 20mg of USP Estrone RS,accurately weighed,to a 100-mLvolumetric flask,add methanol to volume,and mix.If necessary,sonicate to aid solution.Transfer 5mLof this solution to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix to obtain a Standard preparationhaving a known concentration of about 40µg of USP Estrone RSper mL.
Assay preparation—
Transfer about 20mg of Estrone,accurately weighed,to a 100-mLvolumetric flask,add methanol to volume,and mix.If necessary,sonicate to aid solution.Transfer 5.0mLof this solution to a 25-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Chromatographic system(see Chromatography á621ñ)—
The liquid chromatograph is equipped with a 280-nm detector and a 4-mm ×15-cm column that contains 5-µm packing L1.The flow rate is about 1mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency determined from the analyte peak is not less than 1500theoretical plates,the tailing factor for the analyte peak is not more than 2.0,and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 50µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C18H22O2in the portion of Estrone taken by the formula:
0.5C(rU/rS),
in which Cis the concentration,in µg per mL,of USP Estrone RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information—
Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 780
Pharmacopeial Forum:Volume No.29(5)Page 1479
Phone Number:1-301-816-8139