Quality control methods for

N.B. This test should be applied only if specifically required for a given plant 
material. 
Inspection by microscopy 
Once the material has been examined and classified according to external 
characteristics, inspection by microscopy can be carried out as the next step. 
Equipment 
The following are required: 
- 
a microscope equipped with lenses providing a wide range of 
magnification and a substage condenser, a graduated mechanical stage, 
objectives with a magnification of 4x, 10x, and 40x, and colour filters of 
ground glass, blue-green; high eyepoint eyepieces are preferred for 
wearers of spectacles; 

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Quality control methods for medicinal plant materials 
- 
a lamp, either separate or incorporated into the microscope;
- 
a set of polarizing filters; 
- 
a stage micrometer and an ocular micrometer to be inserted into a 6x 
eyepiece and placed on the diaphragm or, preferably, a micrometer 
eyepiece; 
- 
a set of drawing attachments for the microscope;
- 
a microburner (Bunsen type); 
- 
slides and cover-glasses of standard size;
- 
a set of botanical dissecting instruments. 
Recommended procedures 
 
Preliminary treatment 
Select a representative sample of the material. Dried parts of a plant may require 
softening before preparation for microscopy, preferably by being placed in a 
moist atmosphere, or by soaking in water. For small quantities of material, place 
a wad of cotton-wool moistened with water into the bottom of a test-tube and 
cover with a piece of filter-paper. Place the material being examined on the 
paper, stopper the tube and allow to stand overnight or until the material is soft 
and suitable for cutting. Use a desiccator for larger quantities of material, 
placing water into the lower part instead of the drying agent. 
Bark, wood and other dense and hard materials usually need to be soaked in 
water or equal parts of water, ethanol and glycerol for a few hours or overnight 
until they are soft enough to be cut. Boiling in water for a few minutes may 
sometimes be necessary. 
Any water-soluble contents can be removed from the cells by soaking in water. 
Starch grains can be gelatinized by heating in water. In certain cases, material 
can be moistened with water for a few minutes to soften the surfaces and allow 
sections to be cut.