AOAC Official Method 974.43 Ethinyl Estradiol in Drugs
Spectrophotometric Method
First Action 1974
Final Action 1976
A. Reagents
(a) Methanol–sulfuric acid.—In ice bath, cautiously add chilled H2SO4 (³95%) in small increments, with mixing, to 60 mL chilled anhydrous methanol in 200 mL volumetric flask. Cool to room temperature, dilute to volume with H2SO4, and mix. Reagent is stable at room temperature ca 1 month.
(b) Washed chloroform.—Vigorously shake ca 500 mL CHCl3 with 30 mLH2SO4 (³95%) in 1 L separator ca 2 min. DiscardH2SO4 (bottom) layer. Wash CHCl3 with 400 mL H2O by shaking vigorously 1 min; discard H2O. Repeat H2O washing 3 times as above. Filter clear CHCl3 layer through funnel containing pad of glass wool covered with ca 50 g granular anhydrous Na2SO4. Prepare fresh daily. Use same batch of washed CHCl3 for all samples and standards throughout series.
