On some analytical aspects of the determination of fullerenes in samples from the permian/triassic boundary layers

In a recent paper [Science 291 (2001) 1530] Becker et al. explain the greatest extinctions in the earth history at the P/Tr boundary by the impact of an extraterrestrial object and consider that hypothesis proven by the presence of C60 and C60 endohedrally filled by extraterrestrial helium and argon isotope ratio they determined in P/Tr boundary layers. This paper raises some analytical aspects of those determinations which do not seem to be sufficiently well founded.