Crystallography Microcrystal tests for detection of Alkaloids

1. Crystallography
Microcrystal tests for detection of Alkaloids
Faculty of Pharmacy, Pharmacognosy Department
Under Supervision of
Dr. Enas Ibrahim
Prepared BY:
Mona Ismail

2. Crystallography
Rapid micro-chemical test used in alkaloids identification
Importance of alkaloid identification
 Pharmaceutical quality control
 Addiction detection
 Forensic problems
 Alkaloids form double salts with salts of heavy metals, such as,
gold (Au), mercury (Hg) and platinum (Pt).
 The resulting double salts are found to be possessing
characteristic microcrystalline structures.
 Alkaloid with certain reagent give specific crystals

3. Example of alkaloids
Reagent
Alkaloids
Mercuric chloride (HgCl2)
1- Caffeine
Mercuric chloride (HgCl2)
2- Nicotine
Zinc chloride (ZnCl2)
3- Papaverine
Disodium hydrogen phosphate (Na2HPO4)
4- Quinine
Wagner's reagent (I2/KI)
5- Atropine

4. Sample preparation for microscope examination:-
One drop of alk. Soln.
By Micropipette
+ One drop of reagent
By Micropipette
Mix two drops
Examine the slide under microscope without cover

5. Alkaloid Reagent ppt. Time Position
Crystal shape &
Description
Caffeine HgCl2 ‫ــــــــــــــ‬ immediately
From the
center to the
whole slide
Clusters of very long
radiating needles with
tapering ends
1- Caffeine
Under Microscope

6. Alkaloid Reagent ppt. Time Position
Crystal shape &
Description
Nicotine HgCl2 White ppt.
Less than 1
min.
Near the
margin
Radiating transparent
plates which are finger
like
2- Nicotine
Under Microscope

7. Alkaloid Reagent ppt. Time Position
Crystal shape &
Description
Papaverine ZnCl2
White ppt.
after few
seconds
Less than 1
min.
The whole slide
Thin transparent
rectangular plates
3- Papaverine
Under Microscope

8. Alkaloid Reagent ppt. Time Position
Crystal shape &
Description
Quinine Na2HPO4 ‫ـــــــــــــــ‬ (1-2) min. On the margin
Silvery, sheaves like
radiating needles
4- Quinine
Under Microscope

9. Alkaloid Reagent ppt. Time Position
Crystal shape &
Description
Atropine
Wagner's
reagent
(I2/KI)
Reddish
brown
ppt.
Immediately appears
as small rods &
increasing in size
within 1 min.
From the
margin to the
whole slide
Small dark rods
and triangular
plates single or in
groups
5- Atropine
Under Microscope

10. Alkaloid Reagent ppt. Time Position
Crystal
description
Crystal shape
Caffeine HgCl2 ‫ــــــــــــــ‬ immediately
From the
center to
the whole
slide
Clusters of very
long radiating
needles with
tapering ends
Nicotine HgCl2 White ppt.
Less than 1
min.
Near the
margin
Radiating
transparent plates
which are finger
like
Papaverine ZnCl2
White ppt.
after few
seconds
Less than 1
min.
The whole
slide
Thin transparent
rectangular plates
Quinine Na2HPO4 ‫ـــــــــــــــ‬ (1-2) min.
On the
margin
Silvery, sheaves
like radiating
needles
Atropine
Wagner's
reagent
(I2/KI)
Reddish
brown
ppt.
Immediately
appears as
small rods &
increasing in
size within 1
min.
From the
margin to
the whole
slide
Small dark rods
and triangular
plates single or in
groups
Summary