Foreign alkaloids present in alkaloidal drugs

Materials Required Silica gel G mobile-phase (acetone water 13, 5 M ammonia 90 7 3) 100 ml solution (1,2% w/v of sample in methanol solution (2) 0.02% w/v of sample in methanol solution (3 0.01% w/v of sample in methanol dilute potassium iodobismuthate solution (dissolve 100 g of (+) -tartaric acid in 500 ml of water and add 50 ml of potassium iodobismuthate solution RI ) 100 ml  

Procedure Apply separately to the coated TLC plate 1 p/ of each of three solutions (1), (2) and (3). Develop the plate in the above mobile-phase such that the solvent front is allowed to ascend only 10 cm above the line of application. After removal of the plate, dry it at 100 °C to 105 °C for 15 minutes, allow to cool and spray with dilute potassium iodobismuthate solution until spots appear. 

Observations Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot obtained with solution (2), and not more than one such spot is more intense than the spot obtained with solution (3). 

The presence of foreign alkaloids in Codeine (BP) may be determined by more or less an identical method as already discussed in section 28.4.3 earlier. 

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