1. Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6, Canada
2. Carleton Mass Spectrometry Centre, Carleton University, Ottawa, Ontario K1S 5B6, Canada
3. Institute of Biochemistry, Carleton University, Ottawa, Ontario K1S 5B6, Canada
4. Pasarow Mass Spectrometry Laboratory, Jane and Terry Semel Institute for Neuroscience and Human Behavior and the Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90024, United States of America