Example chromatograms. Shown are two transitions from the five most common analytes (OH- and Me-pseudocobalamin and OH-, Me-, and Ado-cobalamin) in standards, cultures (Nitrosopumilus SCM1 and Prochlorococcus MED4), and the environment (surface sample from Station 1). Both the primary (used for quantification, black) and secondary (used for identity confirmation, gray) fragment ions are shown with an arbitrary y axis (ion intensity).