Standards Development

Scope

This document specifies two titrations methods of determining the acid value in essential oils. These two methods are not applicable to essential oils containing appreciable quantities of lactones (Exemple: Massoïa essential oil).

Purpose

This standard presents the measurement of acid index by acid / base measurement using a titrated ethanolic solution of potassium hydroxide. The method is both too precise on certain points and too imprecise on others.

- More flexibility on the method would be appreciable (material, sample weight, colored indicator, automatic method ...) without modifying its principle of dosage acid / base. For example, the current standard only shows the manual method (burette) with precisely described and fixed material whereas it is possible to adapt it with the concentrations of the titrant solution. The use of a 2mL burette and a 0.1 mol / L titrating solution could be replaced by a 5mL burette with a 0.05 mol / L titrating solution. Regarding the colored indicators used, thymolphthalein is also suitable.

- Given the variability of essential oils, their color and their acid index (between 0 and 100 roughly) a table specifying the sample weights according to the expected index would guide the user. The current standard sets the test portion at 2g of essential oil. This weight is only suitable for essential oil with acid index close to 1 taking into account the material described. It should be adapted so that measurements can be made for all types of essential oils.