Authors:Boglárka Bagócsi, Zoltán Végh, and Katalin Ferenczi-Fodor
The acidic visualization methods most often used for steroids have been optimized and compared. Sulfuric acid at three different concentrations, phosphomolybdic acid, and phosphoric acid, with different heating temperatures for different times, have been examined as reagents for visualization of seven steroids separated by OPLC on HPTLC silica gel as adsorbent. For sulfuric and phosphoric acids the chromatograms were evaluated by inspection under long-wavelength UV light (366 nm). For phosphomolybdic acid the chromatograms were evaluated in daylight. It was found that visualization at higher temperatures for shorter periods usually results in greater sensitivity, although heating for longer periods at lower temperatures results in a more stable, robust visualization.
Authors:Boglárka Bagócsi, Dénes Fábián, Anna Laukó, Mária Mezei, Sándor Mahó, Zoltán Végh, and Katalin Ferenczi-Fodor
A semiquantitative OPLC purity test has been developed for inprocess control of nandrolone and compared with other chromatographic methods. TLC was not sufficiently selective, a key impurity with low UV absorption could not be detected by HPLC, and nandrolone was slightly degraded during gas chromatography. OPLC proved to be a suitable means of testing for all potential impurities in nandrolone. The separation was performed by multiple development on fine-particle silica gel with cyclohexane-ethyl acetate-chloroform, 50 + 25 + 25 (
), as mobile phase. After spraying the chromatograms with sulfuric acid, then heating, the impurities could be sensitively detected by visual inspection in long-wave UV light. Detection limits were ≤0.01 μg.
Authors:Boglárka Bagócsi, Géza Rippel, Mária Mezei, Zoltán Végh, and Katalin Ferenczi-Fodor
An OPLC purity test suitable for routine analysis of norethisterone bulk drug substance and in tablets has been developed. Separation was performed on a fine-particle silica gel adsorbent layer by continuous development with
-hexane and butyl acetate-chloroform, 85 + 15 (
), as mobile phases. Visualization of the chromatogram by use of sulfuric acid enables detection of less than 0.05% of possible impurities by use of long-wave UV illumination. The selectivity and efficiency of this OPLC method were compared with those of the pharmacopeial TLC methods and those of HPLC method.