Page 18 - phytochemistry II -pharmD general
P. 18
➢ Separation of a mixture of 4ry and N-Oxide alks:
• The mixture is dissolved in H2O (both are dissolved).
• Precipitation of 4ry alk. by addition of ammonium reineckate, then filter
Qualitative tests for alkaloids:
Alkaloids precipitation reagents:
1. Mayer’s reagent (potassium-mercuric iodide solution).
2. Wagner's reagent (solution of iodine potassium iodide), that gives a reddish
brown precipitate.
3. Hager's reagent (a saturated solution of picric acid), that gives a yellow
precipitate.
4. Dragendorff's reagent (solution of potassium bismuth iodide), that gives an
orange to reddish brown precipitate.
Alkaloids Colour reagents
1. Mandalin's reagent: (sulphovanadic acid) Ammonium vanadate in conc.
H2SO4.
2. Froehd's reagent: (sulphomolybdic acid) Molybdic acid or sodium
molybdate in conc. H2SO4. The reagent should be freshly prepared before
use.
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