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Abstract
We present a two dimensional (2D) planar chromatographic separation of ethinyl steroids on cyanopropyl phase. A mixture of nine steroids was separated by using a cyanopropyl-coated silica gel plate (Merck, 1.16464) with the solvent mix of dichloromethane, methanol, cyclohexane (95 + 5 + 60, v/v) in the first direction and with a mixture of water, acetonitrile, ethanol, dioxane, and NH3 (25%) (8 + 2 + 1 + 1 + 0.05, v/v) in the second direction. Both developments were carried out over a distance of 70 mm. The steroids were catalytically transformed into fluorescent compounds that can be sensitively detected. The fluorescence was measured by a simple 8-bit CCD-camera. The range of linearity covers two magnitudes of power using the extended Kubelka-Munk expression for data transformation. This separation method is inexpensive, fast, and reliable and can be used to quantify 17α-ethinylestradiol (EE2) in the effluents of waste water treatment plants at an LOD of 2 ng per spot. Using a solid phase extraction pretreatment procedure achieves an LOD of 2 ng L−1 water.
ACKNOWLEDGMENT
The authors express their appreciation to Merck-Company (Darmstadt, Germany), BioStep (Jahnsdorf, Germany) and DESAGA GmbH (Wiesloch, Germany) for their kind support.