An Improved Method for Fractionation of Small Quantities of Lettuce Latex

Abstract

While large quantities of latex can be handled either by standard extraction techniques such as Soxhlet extraction or accelerated solvent extraction (ASE), smaller samples on the order of 0.3 - 0.5 g require handling on a microscale. We collected latex from lettuce plants in microcentrifuge tubes and, after drying under vacuum, resuspended the dried sample in acetone by holding in an ultrasonic cleaner. The resulting fine suspension was readily extracted with acetone and toluene to provide fractions representing the resin and rubber content of the latex. Using this approach, we compared latex from stems of bolting lettuce and from the floral stem of lettuce plants. While both types of stems contained a similar percentage of resin, the rubber content of the bolting stems exceeded that of the floral stems.