Appendix X K. Determination of Aldehydes

To 1 g of the oil in a glass-stoppered tube (approximately 150 mm × 25 mm) add 5 mL of toluene and 15 mL of alcoholic hydroxylamine solution, shake vigorously and titrate immediately with 0.5m potassium hydroxide in ethanol (60%) VS until the red colour changes to yellow. Continue shaking and neutralising 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 0.5m potassium hydroxide in ethanol (60%) VS. Calculate the content of aldehydes from the second determination, using the equivalent given in the monograph.