1. Dep. of Plant Sciences Univ. of Saskatchewan 51 Campus Dr. Saskatoon SK S7N 5A8 Canada
2. Dep. of Chemistry Univ. of Winnipeg 599 Portage Ave. Winnipeg MB R3B 2G3 Canada
3. Centre for Veterinary Drug Residues Canadian Food Inspection Agency 116 Veterinary Rd. Saskatoon SK S7N 2R3 Canada