Selective Colorimetric Determination of Microgram Amounts of Quinestrol and Ethinyl Estradiol in Dosage Forms

Validation of Methanol-Sulfuric Acid Colorimetry as a Stability Assay Method for Quinestrol by Comparison with a Gas Chromatographic Procedure

“…The previously reported procedure (1) has been modified to provide fewer manipulations and to eliminate interference from ethinyl estradiol. The following procedure is recommended.…”

“…Khoury and Cali (2, 3) inferred that sulfuric acid-induced fluorescence is specific for undegraded ethinyl estradiol from their finding that only the undegraded steroid gave a fluorescent spot on a thin-layer chromatogram of thermally or photochemically degraded material. This report describes validation of the previously reported colorimetric assay (1) as a stability method for quinestrol dosage forms. A linear correlation is demonstrated between assay results obtained by the colorimetric method and a specific gas chromatography procedure on quinestrol samples partly degraded by heating with acid, alkali, or hydrogen peroxide.…”

“…The pink color formed by reaction of ethinyl estradiol or its 3-ethers, quinestrol and mestranol, with a methanol-sulfuric acid reagent was shown to be a highly selective means for determining these estrogenic steroids by Tsilifonis and Chafetz (1) ; several closely related estrogens give either no color or noninterfering yellow colors under the prescribed conditions. Khoury and Cali (2, 3) recently described a fluorometric assay for ethinyl estradiol and mestranol which makes use of 90% sulfuric acid as the fluorogenic reagent.…”

Spectrophotofluorometric Determination of Mestranol in Oral Contraceptive Tablets

“…Because of its low dosage in tablets, mestranol is difficult to assay. UV (1)(2)(3), GLC (4-S), and colorimetric (9)(10)(11)(12)(13)(14) methods have been proposed but all lack specificity or are unsuitable for routine analysis.…”

Selective Colorimetric Determination of Ethynodiol Diacetate in Oral Estrogen-Progestin Combination

“…Many analytical techniques such as gas chromatography (1-9, thin-layer chromatography (TLC) (1)(2)(3)(4)(5)(6), UV spectrophotometry (4-6), fluorometry (5,7,8), and colorimetry (5,(8)(9)(10) have been used for the determination of the estrogen component (ethinylestradiol or mestranol) present in the estrogen-progestin tablets and the procedures are abundantly described in literature.…”