This International Standard specifies a method for the determination of the carbonyl value of essential oils. It is applicable to essential oils which contain carbonyl compounds (especially ketones, excluding methylketones) which are difficult to convert to oximes by the method specified in ISO 1279. The method is not applicable to essential oils which contain substantial amounts of esters or other alkali-sensitive constituents. International Standards specifying requirements for individual essential oils will specify whether this method or the hydroxylammonium chloride method specified in ISO 12791) is applicable.