Suffering from 'mystery-blob-itis' I searched the BB archives, and read about the various degradation products of PEG. I used this information to model my blobs as oxalate. Job done. Except that now I need a reference for a paper, and I can't find any. Can anyone point me in the right direction? Alice Alice Dawson Biological Chemistry and Drug Discovery College of Life Sciences The Welcome Trust Building University of Dundee Dow Street Dundee DD1 5EH Tel. 01382 385744 [log in to unmask]