Pollen purification and fractionation by equilibrium density gradient centrifugation

Abstract
Density gradient centrifugation was used to fractionate mixtures containing either modern or fossil palynomorphs. In addition it removed detrital organic material from fossil preparations without significantly altering palynomorph proportions. A taxonomic aspect to fractionation was observed: it was possible to separate both fossil and modern mixtures of palynomorphs into groups, some of which were composed of related taxa. We conclude that density gradient centrifugation could be used to extract palynomorphs from the organic matrix, and/or to isolate individual groups of taxa.