Hi There can easily be another problem with drying sucrose: dehydration (by which I mean CH2O -> C + H2O). I've dried samples at less than 100 degrees C and, in the presence of some impurities, they have dehydrated (caramlysed) quite substantially. Even traces of acid will do this, for example. Phloem samples have also shown that behaviour. Vacuum drying produces the effect at even lower temperatures. For example a student here vacuum dried a 0.01 molar solution of HCl and sucrose at room temperature and produced something fit only to be mixed with custard. Is there an associated fractionation? I don't know. Hil . Hilary Stuart-Williams PhD Research Officer Environmental Biology Research School of Biological Sciences The Australian National University Canberra, Australia ACT 0200 Telephone +61 2 6125 2099 Fax +61 2 6125 4919 www.rsbs.anu.edu.au/content/research%20groups/Environmental%20Biology.asp