Thin Layer TLC and Paper Chromatographs PC

Opium alkaloids are most commonly estimated by separating them on a chromatographic paper (PC) and/or on a thin layer chromatographic plate (TLC). The former needs a longer time for developing spots than on the silica gel layers of TLC. After the separation of different opium alkaloids with different mobile phase systems of PC and TLC, individual alkaloids are quantitatively measured by eluting the spot and using different procedures, like spot area measurement, spectrophotometry, IR spectroscopy, densitometry, etc. Important methods are described below  

Mary and Brochmann-Hanssen (1963) developed a sound method of TLC coupled with spectrophotometry for quantitative analysis of opium alkaloids in a single extraction. The method runs as follows. 

Preparation of Opium Extracts. 200mg of finally powdered opium is triturated to a paste in a glass mortar and pestled with 0.5 ml methanol and 0.5 ml concentrated ammonium hydroxide solution. Then 3g of aluminum oxide is added and the trituration continued until a homogeneous free-flowing powder is obtained. The triturate is then transferred quantitatively to a chromatographic column (30 x 1cm). The alkaloids are eluted with 80 ml of a mixture of chloroform-isopropyl alcohol (3 1). The rate of flow is adjusted to about one drop per second. The eluate is finally concentrated almost to dryness under vacuum and then transferred to a small vial to evaporate to dryness in a stream of nitrogen to obtain the opium extract. 

Standard Solution and TLC. A 0.25% (w/v) of each of the alkaloid bases in MeOH CHCl3 (1 4) is taken as standard alkaloid solution. MeOH CHCl3 (1 9) is used as developing solvent for morphine, codeine, and thebaine, and EtOH C6H6 (1 4) for papaverine and narcotine TLC on silica gel 

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