In this study the chemical structure of algaenans isolated from the freshwa
ter algae Tetraedron minimum, Pediastrum boryanum and Botryococcus braunii
are compared with their fossil counterparts by means of RuO4 oxidation. The
results show that the algaenans investigated are preserved in sediments wi
th only minor structural alterations. However, product mixtures from RuO4 d
egradation of the fossil algaenans exhibit a broader distribution of oxidat
ion products than freshly isolated algaenans indicating that the fossil bio
polymers contain a greater proportion of ether cross-links, which maybe: an
effect of diagenetic alteration or different algal strains. Despite these
differences, fossil algaenans can still be recognised chemically on the bas
is of the specific RuO4 oxidation products. even after 50 Ma of sediment bu
rial. Copyright (C) 2000 Elsevier Science Ltd.