A comparison between two systems of volatile sampling in flowers of alfalfa (Medicago sativa L.)

A steam distillation method and dynamic headspace system with Tenax adsorbent resin were used to collect volatile components from alfalfa flowers. After GC and GC/MS analyses several components were identified by both techniques and qualitative and quantitative differences were found. Aldehydes were the most abundant compounds detected with the Tenax method, and quantified as 52.7% of the total volatiles. Alcohols and ketones were also detected in 23.5% and 19.6% amounts, respectively. In the steam distillate, alcohols represented 65.0% of the total, followed by aldehydes (19.5%) and ketones (2.9%). In addition, other classes of components were detected, such as esters, terpenes, hydrocarbons and some miscellaneous compounds, although in constantly low amount. Acids were only detected in the steam distillate. Differences in qualitative and quantitative composition of volatiles obtained from the two methods were examined and discussed. Copyright © 2000 John Wiley & Sons, Ltd.