Principles and Practice of Chromatography - Chromatography Applications > Liquid Chromatography Applications > Page 84
The column appears to be significantly overloaded in order to identify the impurities, Nevertheless, the impurities were well separated from the main component and the presence of a substance was demonstrated in the generic formulation that was not present in the Darvocet®. The mobile phase consisted of a mixture of 98.5% dichloromethane with 1.5% v/v of methanol containing 3.3% ammonium hydroxide. The ammoniacal methanol deactivated the silica gel but the interaction of the solutes with the stationary phase would still be polar in nature. In contrast solute interactions with the methylene dichloride would be exclusively dispersive.
The separation of some steroid hormones is another example of the use of silica gel as an interactive stationary phase the separation obtained is shown in figure 45.
Courtesy of Supelco Inc.
(Supplied to Supelco by Dr. S. N. Rao and Prof. M. Okamato, Cornell University Medical College, New York)
Figure 45 The Separation of Steroid Hormones