Analysis of steroids. Part XXIV. A specific method for the spectrophotometric determination of 17-ethynyl steroids

Abstract

The investigation of the equilibrium between 17-keto steroids, acetylene and 17-ethynyl steroids has afforded two possibilities for its analytical application. On the one hand, the 17-ethynyl steroids can be quantitatively converted into 17-keto steroids and the latter determined spectrophotometrically as their 16-glyoxalyl derivatives (Amax. = 294 nm, E = 10 700 and u = 1-1 per cent.). On the other hand, a t 0 "C the 17-keto steroid contaminants in 17-ethynyl steroids can be selectively determined on the same principle.These methods cannot be applied in the investigation of 3-keto steroids.THE introduction of the 17-ethynyl group into various steroid hormones greatly enhances their hormonal activity. The resulting "super gestogens" and "super oestrogens" can be used in very small doses, hence the micro-determination of these compounds is very important. Most of the existing micro-scale methods for the determination of 17-ethynyl steroids involve ultravioletl*2 and infrared3 spectrophotometric, colorimetric4-0 and fluorimetric6 procedures, which usually depend on other functional groups in the steroid molecule such as the a,p-unsaturated 3-keto group of the phenolic A-ring. These and many other methods of similar nature are very sensitive, but are not, however, specific for the ethynyl group, The specific determination of the 17-ethynyl group can be performed by argentimetricacidimetric * For details of Part XXIII of this series, see

Chemical and analytical characterization of related organic impurities in drugs

“…For example, salicylic acid is the hydrolytic decomposition product of acetylsalicylic acid. Base-catalyzed [26] or thermal degradation of 17-ethynyl steroids can also lead to 17-oxosteroids. (This is why gas chromatography is not suitable for the determination of the latter in 17-ethynyl steroids [3,27].…”

Simultaneous Determination of Ethinylestradiol and Levonorgestrel in Oral Contraceptives by Derivative Spectrophotometry

“…There have been several reports [1][2][3][4][5][6][7][8][9][10][11] of the determination of levonorgestrel or ethinylestradiol, including the use of radio-actively labelled derivatives, 1,2 dansyl or other fluorescent derivatives, [3][4][5] spectrophotometry or photometry [6][7][8][9] and gel or column chromatography, but the methods are complicated. 10,11 No references were found to the simultaneous determination of ETE and LEV using spectrophotometric methods.…”