1. National Veterinary Institute, P.B. 8156 Dep., 0033 Oslo, Norway; Chemistry Department, The University of Waikato, Private Bag 3105, Hamilton, New Zealand; Biotoxin Chemistry, Marine Institute, Galway Technology Park, Parkmore, Galway, Ireland; Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, NO 0315 Oslo, Norway; and AgResearch Ltd., Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand