2.6.2 Quantitative Determination of Volatile Oil in a Plant Material
The necessity to determine the volatile oil quantitatively from a plant material is mostly accomplished by a specially designed apparatus , which helps in ascertaining the raw material to be employed for commercial production. Such a determination is also extremely helpful in establishing and appraising the quality of spices and oleoresins.
Clavenger devised an apparatus to determine the volatile oils which essentially has several advantages, namely: (a) Compactness in size, (b) Cohobation of distillation waters, and (c) Reasonably accurate estimation of volatile oil content by employing relatively smaller quantum of the raw material. However, the apparatus also possesses an additional merit for steamrectificationof small quantities of essential oils.
Apparatus It consists of a round bottomed flask of varying capacity from 1 L to 2 L which is provided with a hanging type heating mantle and regulator. The mouth of the round bottomed flask is connected with a specifically designed trap to collect the volatile oil which could be either heavier than water or lighter than water as shown in Figure 5.3.
The various vital components of the apparatus for the quantitative estimation of volatile oils are as follows:
A = RB–flask,
B = Heating Mantle (Hanging type),
C = Drug and water
D = Bend insulted with asbestos/ cotton pad
E = Water condenser
F = Inlet – for water
G = Outlet – for water
H = Volatile oil collected in a graduated stem
I = Excess water reintroduced in round bottomed flask
Methodology A known weight of the drug either as such powdered or cut into small pieces is introduced into the round bottomed corning flask (1 L or 2 L capacity) along with a distillation
Fig. 5.3 Apparatus for Quantitative Estimation of Volatile Oils
medium which often is fresh water or a mixture of water and glycerin. The quantity of this medium is usually 3 to 6 times the weight of the drug substance. The distillation is done for about 5-6 hours.
The distillate is collected in a specially designed trap (or receiver). The stem of which is graduated upto 5 ml with each ml mark is subdivided into 1/10 the ml. In case, the volatile oil is heavier than water the trap on the left hand side of Fig. 5.3 is used; and when the volatile oil is lighter than water the trap on the right hand side is employed.
