Field ionization (FI), field desorption (FD), and liquid injection field desorption/ionization (LIFDI) provide soft positive ionization of gaseous (FI) or condensed phase analytes (FD and LIFDI). In contrast to the well-established positive-ion mode, negative-ion FI or FD have remained rare exceptions. LIFDI provides sample deposition under inert conditions, i.e., the exclusion of atmospheric oxygen and water. Thus, negative-ion LIFDI could potentially be applied to highly sensitive anionic compounds like catalytically active transition metal complexes. This work explores the potential of negative-ion mode using modern mass spectrometers in combination with an LIFDI source and presents first results of the application of negative-ion LIFDI-MS. Experiments were performed on two orthogonal-acceleration time-of-flight (oaTOF) instruments, a JEOL AccuTOF GCx and a Waters Micromass Q-TOF Premier equipped with LIFDI sources from Linden CMS. The examples presented include four ionic liquids (ILs), i.e., N-butyl-3-methylpyridinium dicyanamide, 1-butyl-3-methylimidazolium tricyanomethide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate), 3-(trifluoromethyl)-phenol, dichloromethane, iodine, polyethylene glycol diacid, perfluorononanoic acid, anionic surfactants, a tetraphosphazene silanol-silanolate, and two bis(catecholato)silanes. Volatile samples were delivered as vapors via the sample transfer capillary of the LIFDI probe or via a reservoir inlet. Condensed phase samples were applied to the emitter as dilute solutions via the sample transfer capillary. The compounds either yielded ions corresponding to their intact anions, A⁻, or the [M–H]⁻ species formed upon deprotonation. This study describes the instrumental setups and the operational parameters for robust operation along with a discussion of the negative-ion LIFDI spectra of a variety of compounds.

场电离 (FI)、场解吸 (FD) 和液体注入场解吸/电离 (LIFDI) 提供气态 (FI) 或凝聚相分析物（FD 和 LIFDI）的软正离子化。与成熟的正离子模式相比，负离子 FI 或 FD 仍然是罕见的例外。LIFDI 在惰性条件下提供样品沉积，即排除大气中的氧气和水。因此，负离子 LIFDI 可以潜在地应用于高度敏感的阴离子化合物，如催化活性过渡金属配合物。这项工作探索了将现代质谱仪与 LIFDI 源结合使用的负离子模式的潜力，并展示了负离子 LIFDI-MS 应用的初步结果。在两个正交加速飞行时间 (oaTOF) 仪器上进行了实验，JEOL AccuTOF GCx 和配备来自 Linden CMS 的 LIFDI 源的 Waters Micromass Q-TOF Premier。给出的示例包括四种离子液体 (IL)，即N-丁基-3-甲基吡啶鎓二氰胺、1-丁基-3-甲基咪唑鎓三氰基甲基化物、1-丁基-1-甲基吡咯烷鎓双(三氟甲基磺酰基)亚胺和三己基(十四烷基)鏻三(五氟乙基)三氟磷酸盐)、3-(三氟甲基)-苯酚、二氯甲烷、碘、聚乙二醇二酸、全氟壬酸、阴离子表面活性剂、四磷腈硅烷醇-硅烷醇盐和两种双（邻苯二酚）硅烷。挥发性样品通过 LIFDI 探针的样品传输毛细管或通过储液罐入口以蒸气形式输送。通过样品传输毛细管将凝聚相样品作为稀释溶液施加到发射器上。这些化合物要么产生与其完整阴离子相对应的离子，A ^-，要么 [M-H] ^-去质子化后形成的物种。本研究描述了稳健操作的仪器设置和操作参数，并讨论了各种化合物的负离子 LIFDI 光谱。