A COMPARATIVE-STUDY OF BUCKMINSTERFULLERENE AND HIGHER FULLERENE SEPARATIONS BY HPLC

Several HPLC columns that have been recommended for the separation of fullerenes were compared. Each column (i.e., stationary phase) had a d ifferent optimum mobile phase. In general, mobile phases consisted of binary mixtures of a ''good'' fullerene solvent and a ''poorer'' fulle rene solvent. Reversed phase stationary phases with alkyl (aliphatic) substituents produced superior analytical separations for all fulleren es. However, stationary phases with aromatic substituents were better for preparative separations. Increasing the proportion of the ''poor'' fullerene solvent in the mobile phase generally increased resolution and retention but decreased the mass load. Injecting too high a concen tration of fullerenes in any column caused peak splitting to occur. Th e fullerene retention order was the same on al columns and with all mo bile phases. The fullerene separation ability of all columns tended to deteriorate with time. Overloading the column or doing preparative se parations greatly accelerated the deterioration process. It is believe d that irreversible adsorption of fullerenes or fullerene by-products is responsible for the degradation of column performance.