We have three LC/MS chromatograms collected on a QE instrument. We are looking for ions in Chromatogram 1 that are not present in either Chromatograms 2 and 3. Other than manually interrogating the data sets is there some more convenient/automated approach to this problem? Any and all advice will be appreciated. Kym Kym Francis Faull, Ph.D. Director, Pasarow Mass Spectrometry Laboratory Jane and Terry Semel Institute for Neuroscience and Human Behavior at UCLA Professor Emeritus, Department of Psychiatry and Biobehavioral Sciences David Geffen School of Medicine at UCLA Telephone: (310) 206 7881 (office) Telephone: (310) 206 7886 (laboratory) Facsimile: (310) 206 2161 Electronic mail: <email obscured> <email obscured>>