There are a variety of ways for the instrument to ionize the molecule, which will be discussed here. Electron Impact (EI) ... Chemical Ionization (CI) ... Field Ionization/Desorption. ... Electrospray Ionization (ESI) ... Matrix Assisted Laser Desorption Ionization (MALDI) ... Inductively Coupled Plasma Mass Spectrometry (ICP-MS) More items... Feb 11, 2023