Automated multiple development thin-layer chromatography for separation of opiate alkaloids and derivatives.

ABSTRACT

There are three types of opiate alkaloids. First, the poppy alkaloids morphine, codeine, thebaine, noscapine and papaverine; then, the semi-synthetic and synthetic derivatives used in therapy as antitussives and analgesics, such as pholcodine, ethylmorphine and dextromethorphan; at last narcotic compounds, diacetylmorphine (heroin) and opiates employed as substitutes in treatment of addiction buprenorphine and methadone. For classical thin-layer chromatography (TLC) of opium alkaloids, it is necessary to use complex eluents with strong alkaline substances to obtain a clean separation between morphinan and isoquinoline compounds. This study purposes the planar chromatographic analysis of these substances by the automated multiple development (AMD) compared with results obtained by classical TLC method. The aim of this work was to achieve the best separation of these opiate alkaloids and derivatives by this modern technique of planar chromatography. The AMD system provided a clean separation for each of three opiates groups studied and the best results have been obtained with universal gradient methanol 100, methanol-dichloromethane 50/50, dichloromethane 100, dichloromethane 100, hexane 100 for opium alkaloids and with gradient A 5% of 28% ammonia in methanol 100, acetone 100, acetone 100, ethyl acetate-dichloromethane 50/50, dichloromethane 100 for antitussives and substitutes. Two reagents were used for the detection of alkaloids by spraying Dragendorff and iodoplatinate reagents. The detection limits with these two reagents were 1 microg for ethylmorphine, thebaine, papaverine, codeine, and 2 microg for morphine and noscapine and other alkaloids.