Appendix X J. Determination of Cineole
Weigh 3.00 g of the oil, recently dried with anhydrous sodium sulfate R, into a dry test-tube and add 2.10 g of melted cresol R. Place the tube in the apparatus for the determination of freezing point (2.2.18) and allow to cool, stirring continuously. When crystallisation takes place there is a small rise in temperature. Note the highest temperature reached (t1).
Remelt the mixture on a water-bath at a temperature that does not exceed t1 by more than 5 °C and place the tube in the apparatus, maintained at a temperature 5 °C below t1. When crystallisation takes place, or when the temperature of the mixture has fallen 3 °C below t1, stir continuously. Note the highest temperature at which the mixture crystallises (t2). Repeat the operation until 2 highest values obtained for t2 do not differ by more than 0.2 °C. If supercooling occurs, induce crystallisation by adding a small crystal of the complex consisting of 3.00 g of cineole R and 2.10 g of melted cresol R. If t2 is below 27.4 °C, repeat the determination after the addition of 5.10 g of the complex.
The content of cineole corresponding to the highest temperature observed (t2) is given in Table 2.8.11.-1. If 5.10 g of the complex has been added, calculate the cineole content per cent m/m from the expression:
where A is the value found in Table 2.8.11.-1.
The content of cineole, corresponding to the highest temperature observed (t2), is obtained, where necessary, by interpolation.
