MULTIELEMENTAL CHARACTERIZATION OF SEVERA L BRANDS OF C-60 AND C-70 FULLERENES AND FULLERENE PRECURSORS BY INSTRUMENTAL NEUTRON-ACTIVATION ANALYSIS

Actually, the characterization of the purity of fullerenes is mainly b ased on the concept of defining the percentage amount of the main comp onent (e.g. C-60, C-70, etc.) versus the minor- or micro-fractions of the homologue species and/or other polycyclic organic compounds. But, it has also to be considered that fullerene products may be contaminat ed in some degree by element impurities as well originated both from t he production processes and from the various precursor materials thems elves. We are reporting here for the first time detailed data on trace element impurities in various fullerene precursors as well as in the main C-60 and C-70 fullerene products of different producers measured by instrumental neutron activation analysis (INAA). The concentration distributions of about 35 trace elements have been studied including t he determination of the relevant limits of detection (LoD) values conc erning the experimental conditions applied to the analysis. It could b e established that all fullerene materials investigated contain a broa d scale of trace elements distributed within a fairly wide concentrati on range from ppb (ng/g) up to ppm (mu g/g) levels. For some impurity elements extremely high concentration levels were found indicating tha t elemental impurities have to be considered when studying the electri cal, magnetic and other features of the fullerenes.