Microchemical crystal tests

Chromatographic techniques are the main methods that have been used to separate, detect, and identify organic components of FDR.152 162 Other methods considered include molecular luminescence,163 infrared spectroscopy,164 Raman spectroscopy,165 electron spin response spectrometry,166 microchemical crystal tests,167 168 ultraviolet spectroscopy/nuclear magnetic resonance/polarography.169... 

Caesium chloride reacts with gold and silver solutions to form a complex caesium-silver-gold chloride, crystallizing in opaque cubes. The microchemical identification of one-tenth of a microgram of caesium is possible by means of this test.5... 

In addition to instrumental methods of identification, an analyst may make use of some method of microchemical testing. An excellent discussion of the latter is available5. This work is a systematic study of precipitate tests, color tests, and crystal formation for modern analgesics. Through manipulation of the various testing parameters, Clarke identified a large number of analgesics. Even with the sophisticated instrumentation now available, "wet" methods of identification are still very useful. 

Cytisine (12, 38). The ground tops and seeds of Laburnum vuLgare were air-dried and extracted in a soxhlet with 50 % aqueous ethanol to which had been added 2 % of acetic acid. The extract after concentration was cleared with lead acetate, concentrated, made alkaline with sodium hydroxide, and extracted six times with an equal volume of chloroform. This left only a trace of cytisine in the aqueous layer. When the chloroform was removed, the residual alkaloidal material crystallized in part. No clear-cut separation of components was accomplished by fractional crystallization of the free base or the crude picrate. The isolation of cytisine as the benzenesulfonyl derivative was effected according to the method of Ing (5), and benzenesulfonyl-cytisine was collected and recrystallized from ethanol as glistening prisms, m.p. 261 . Microchemical tests and picrate formation and identification were also used to establish the presence of cytisine in a particular plant. 

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