Comparative GC/MS Analysis of Essential Oils Extracted by 3 Methods from the Bud of Citrus aurantium L. var. amara Engl

A comparative study of steam distillation extraction (SDE), reflux extraction (RE), and ultrasound-assisted extraction (USE) was conducted for the extraction of essential oils from the bud of Citrus aurantium L. var. amara Engl. Each method was evaluated in terms of qualitative and quantitative composition of the isolated essential oil by gas chromatography/mass spectrometry (GC/MS). The extract yields of essential oil were 0.16%, 2.18%, and 2.34%, respectively. A total of 82 compounds were identified by GC/MS. The main components obtained by SDE were terpinen-4-ol (20.98%), dipentene (11.67%), terpinene (9.24%), those by RE were palmitic acid (20.61%), 2-chloroethyl linoleate (14.54%), tetracosane (12.26%), and a-linolenic acid (11.24%), and those by USE were tetracosane (11.32%), heneicosane (11.06%), and palmitic acid (8.76%). Comparative analysis indicated that SDE was favorable for the extraction of monoterpene hydrocarbons, sesquiterpene hydrocarbons, alcohols, and carbonyl compounds, RE and USE had certain advantages in the extraction of aliphatic saturated hydrocarbons, organic acids, and esters. It is concluded that different extraction methods may lead to different yields of essential oils; the choice of appropriate method is very important to obtain more desired components with higher physiological activities.