1. Structural and Biological Mass Spectrometry Unit, Department of Medical Bioanalysis, IIBB-CSIC, IDIBAPS, Rosellón 161, 08036 Barcelona, Spain, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, and Centro de Investigación sobre el Síndrome del Aceite Tóxico (CISAT), Instituto de Salud Carlos III, Sinesio Delgado, 6, 28029 Madrid, Spain.