USE OF AN ACRYLIC ESTER SORBENT FOR THE SELECTIVE ADSORPTION OF AVERMECTINS

Previous work has shown that simple model solutes differing in their abilities to form hydrogen bonds can be selectively adsorbed from a nonpolar solvent onto an acrylic ester sorbent (Amberlite XAD-7). The goal of this work was to determine whether these sorbents could be used for the selective adsorption of members of the avermectin family of secondary metabolites. When the individual avermectins were studied, avermectin B-2a, which has four hydroxyl groups, was observed to adsorb from hexane with a higher affinity than avermectins A(2a) or B-1a, which have only three hydroxyl groups each. When equimolar mixtures of the three avermectins were studied, it was observed that avermectin B-2a was preferentially adsorbed from hexane with separation factors of 2.2 +/- 0.2 and 1.8 +/- 0.2 relative to avermectins A(2a) and B-1a, respectively.