Low-resolution ion spectrum from mass 13.5 to 19.5 u/e. There may be a peak at mass 14 (probably CH) and there are certainly peaks at mass 15 through mass 19 (primarily water group ions, with H₃O⁺ at mass 19, and O⁺, CH, at mass 16 and 15, respectively). Apparent peaks at masses 13.6, 14.4, and 17.4 are not real. They are the result of a combination of mass spectra with a gradient in the offset across the DFMS detector.