1. Department of Chemistry; Norwegian University of Science and Technology; Høgskoleringen 5 NO-7491 Trondheim Norway
2. Chiron AS; Stiklestadveien 1 7041 Trondheim Norway
3. Division of Forensic Toxicology and Drug Abuse; Norwegian Institute of Public Health; PO Box 4404 Nydalen N-0403 Oslo Norway