Molecular characterization of high affinity, high capacity clays for the equilibrium sorption of ergotamine

Ergot alkaloids (mycotoxins) produced by Claviceps and Neotyphodium species of fungi may contaminate animal feedstuffs and result in disease in livest ock. In this study, diverse phyllosilicate clays and other adsorbent materi als, differing in chemical and structural characteristics, were tested for their ability to sorb ergotamine, a prevalent ergot mycotoxin, from acidic solution. Results indicated minimal binding to those sorbents possessing lo w sur;face area, cation exchange capacity and inaccessible interlayer regio ns. Cetyl pyridinium-exchanged montmorillonite (organoclay) exhibited decre ased propensity for ergotamine in acidic solution as compared with the unex changed hydrophilic parent clay. The highest ergotamine sorption was observ ed with cation exchanged montmorillonite clays, whereas, when collapsed, th ese same clays sorbed very little ligand. Based on initial binding experime nts, calcium and sodium montmorillonite clays were prioritized for further characterization, including. capacity, affinity, and heat (enthalpy) of ads orption. Computer models of energy-minimized ergotamine isomers and clay we re used to illustrate possible mechanisms of ergot alkaloid sorption at int erlayer sites. Additional studies are warranted to assess the stability of ergot alkaloid/clay complexes under alkaline conditions to fur ther underst and the mechanism of adsorption.