Thin-layer chromatographic screening procedure for undeclared synthetic drugs in Chinese herbal preparations

A simple and rapid thin-layer chromatographic procedure was developed for the detection and presumptive identification of seventeen synthetic drugs previously reported as adulterants of Chinese herbal preparations. Depending on its complexity, the sample may be directly extracted into aqueous ethanol, or stepwise fractionated into acidic, basic, and neutral components. Extracts are analyzed on silica gel layers containing a fluorescent indicator with the aid of two solvent systems. Spots are visualized under short and long wavelength ultraviolet lights. The procedure was successfully tested on synthetic and commercial samples.