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7.9 DETERMINATION OF ALDEHYDES

7.9 DETERMINATION OF ALDEHYDES

         To 1 g of the oil, accurately weighed, in a glassstoppered tube (approximately 150 mm × 25 mm) add 5 ml of toluene and 15 ml of hydroxylamine in ethanol (60 per cent) TS, shake vigorously and titrate immediately with 0.5 M potassium hydroxide in ethanol (60 per cent) VS until the red colour changes to yellow. Continue shaking and neutralizing until the full yellow colour of the indicator is permanent in the lower layer after shaking vigorously for 2 minutes and allowing to separate; the reaction is complete in about 15 minutes. This procedure gives an approximate value for the aldehyde content of the oil.

         Repeat this procedure, using as the colour standard for the end-point of the titration the titrated liquid of the first determination with the addition of 0.5 ml of 0.5 M potassium hydroxide in ethanol (60 per cent) VS. Calculate the content of aldehydes from the second determination, using the equivalent given in the monograph.

APPENDICES • 7.9 DETERMINATION OF ALDEHYDES
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หมายเหตุ / Note : TP II 2011 PAGE 519