Quality control methods for

Recommended procedure 
Carry out the determination by steam distillation. Collect the distillate in a 
graduated tube, using xylene R or the solvent specified for the plant material 
concerned, and allow the aqueous phase to recirculate into the distillation flask. 
For all determinations read the rate of distillation from the marks engraved on 
the apparatus. 
Apparatus 
A suitable apparatus is made from resistant glass with a low expansion 
coefficient, and has the following parts: 
• a round-bottomed, short-necked flask, capacity 500 or 1000 ml, the internal 
diameter of the ground-glass neck being 29 mm at the widest end; 
• the following sections fused into one piece (Fig. 5): 
- a vertical tube (AC), 210-260 mm long, with an external diameter of 13-15 
mm; 
- a bent tube (CDE), CD and DE each being 145-155 mm long, and having 
an external diameter of 10 mm; 
- a bulb-condenser (FG), 145-155 mm long; 
- a tube (GH) 30-40 mm long, with a side-arm tube (HK), at an angle of 30-
40°; 
- a vented ground-glass stopper (K') and a tube (K) with an internal 
diameter of 10 mm, the wide end being of ground glass; 
- a pear-shaped bulb (J) with a volume of 3 ml; 
- a tube with a volume of 1 ml (JL), graduated over 100-110 mm in 
divisions of 0.01 ml; 

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Quality control methods for medicinal plant materials 
Fig. 5. Apparatus used to determine volatile oils (dimensions in mm)
1
 

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Quality control methods for medicinal plant materials 
- a bulb-like swelling (L), with a volume of about 2 ml;
- a three-way tap (M); 
- a connecting tube (BM), with an external diameter of 7-8 mm, which is 
fitted in the middle with a security tube (N); the junction (B) should be 
20-25 mm higher than the uppermost graduation; 
• a burner allowing fine control and fitted with a flue, or an electric heating 
device;
• a vertical support with a horizontal ring covered with insulating material. 
Before use, clean the apparatus thoroughly by successive washings, for example 
with acetone R or a suitable detergent, then rinse with water, drain and assemble 
in a suitable place.