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7.8 DETERMINATION OF CINEOLE

7.8 DETERMINATION OF CINEOLE

         Weigh 3.00 g of the oil, recently dried with anhydrous sodium sulfate, into a dry test-tube and add 2.10 g of melted o-cresol. Place the tube in the apparatus for the “Determination of Freezing Temperature” (Appendix 4.4), and allow to cool, stirring continuously. When crystallization 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 5º and place the tube in the apparatus, maintained at a temperature 5º below t1. When crystallization takes place, or when the temperature of the mixture has fallen 3º below t1, stir continuously. Note the highest temperature at which the mixture crystallizes (t2). Repeat the operation until two highest values obtained for t2 do not differ by more than 0.2º. If supercooling occurs, induce crystallization by adding a small crystal of the complex consisting of 3.00 g of cineole and 2.10 g of melted o-cresol. If t2 is below 27.4º, repeat the determination after the addition of 5.10 g of the complex.

         The content of cineole, corresponding to the highest temperature observed (t2) in the Table is obtained, where necessary, by interpolation.

         If 5.10 g of the complex has been added, calculate the cineole content in per cent w/w from the expression:

2(A – 50)

Where A is the value found in the Table

APPENDICES • 7.8 DETERMINATION OF CINEOLE
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หมายเหตุ / Note : TP II 2011 PAGE 518