Ethinyl estradiol in oral contraceptive formulations is separated from the sample on a chromatographic column prior to color formation with methanol-sulfuric acid reagent directly in the chloroform-isooctane eluate. Collaborative results on 3 commercial tablet samples averaged 93.93, 98.69, and 98.50% of label claim. The standard deviations and coefficients of variation were 2.61, 2.39, and 2.82, and 2.77, 2.43, and 2.86%, respectively. The method has been adopted as official first action.
A single tablet assay method has been developed for determining norethindrone, norethynodrel, and norgestrel in commercial contraceptive tablets. The steroid is separated from the tablet constituents on a diatomaceous earth column, the chloroform eluate is reacted with isonicotinic acid hydrazide, and the steroid is determined by colorimetry. Norethynodrel is isomerized to a conjugated ketosteroid before the colorimetric determination. Fourteen laboratories collaboratively tested the method. The average recoveries in 3 brands of tablets were as follows: 102.6% for the sample labeled as containing 0.35 mg norethindrone/tablet, 99.4% for the 2.5 mg norethynodrel/tablet, and 98.2% for the 0.5 mg norgestrel/tablet. The assay method has been adopted as official first action.
The present paper describes an anion-exchange chromatography method to separate iron-free apo-Tf (apo-transferrin) from albumin and IgG in Cohn supernatant I. The method uses DEAE-fast flow Sepharose chromatography along with optimized protein concentration (5%, w/v) and column operation conditions (40 g/l, conductivity <1.0 mS/cm) to resolve apo-Tf from IgG and albumin. The single step purifies apo-Tf to >90% and provides an efficient means to obtain commercial quantities of the protein.
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