Ion traps in modern mass spectrometry

Abstract

This review is devoted to trapping mass spectrometry wherein ions are confined by electromagnetic fields for prolonged periods of time within limited volume, with mass measurement taking place within the same volume. Three major types of trapping mass spectrometers are discussed, specifically radiofrequency ion trap, Fourier transform ion cyclotron resonance and Orbitrap. While these three branches are intricately interwoven with each other over their recent history, they also differ greatly in their fundamentals, roots and historical origin. This diversity is reflected also in the difference of viewpoints from which each of these directions is addressed in this review. Following the theme of the issue, we focus on developments mainly associated with the country of Germany but, at the same time, we use this review as an illustration of the rapidly increasing globalization of science and expanding multi-national collaborations.

Broadband lasers for photo-ionization and repumping of trapped ions

“…Using Eqs. (3)(4), we can then calculate the ratio of the fluorescence rates for the DBR laser and the BBL, which for P = 0.88 mW becomes 2.5, in reasonable agreement with the experimental value of 3.3 considering the simple models used and the experimental uncertainties. Equating Eqs.…”

The emerging interface of mass spectrometry with materials

“…Though LDI was used as the primary characterization tool in the 1990s, softer techniques like matrix-assisted laser desorption ionization (MALDI) and ESI became more popular for the ionization of intact ligand-protected clusters. In 1998, Schaff et al reported a 10.4 kDa Au-GSH (GSH = glutathione) cluster, Au 28 (SG) 16 48 . The composition was proposed from both MALDI MS and ESI MS.…”

“…In 2012, Yu et al reported the size controlled growth of Au 25 NCs where they slowed down the reduction rate by using CO as a mild reducing agent 100 . By using MALDI MS, the authors demonstrated that a mixture of Au [10][11][12][13][14][15] NCs was produced within 5 min of reaction, followed by the formation of Au [16][17][18][19][20][21][22][23][24][25] NCs over a period of 40 min, which finally size focussed to Au 25 NCs after 24 h. However, due to fragmentation, only the core masses could be identified, and no information was obtained about the ligand shell of the intermediate 12 Cl] + , [Ag 8 Cu 6 (C≡C t Bu) 12 Cl] + , and [Ag 14 (C≡C t Bu) 12 Br] + cluster ions showing their onsets of ionization. The yield of the product ions as a function of the photon energy is shown for [Ag 14 (C≡C t Bu) 12 Cl] 2+ , [Ag 8 Cu 6 (C≡C t Bu) 12 Cl] 2+ , and [Ag 14 (C≡C t Bu) 12 Br] 2+ .…”

“…The orbitrap was invented in 1999 14 , and at present, they can reach a resolution of 6,00,000 at m/z 195 15 . The gas-phase ions generated inside the mass spectrometer can also be confined for a significant amount of time in "ion traps", and properties of the trapped ions have been studied in the literature 16 . Though MS is mainly used for proteomics these days, it also became popular for studying materials.…”

Neuropeptidomics: Comparison of parallel reaction monitoring and data‐independent acquisition for the analysis of neuropeptides using high‐resolution mass spectrometry

“…For proteomic and peptidomic studies, several mass spectrometer configurations are currently available with specific strengths and weaknesses. Over the last decade, new hybrid mass spectrometers with high-resolution and accurate mass (HRAM) performances were developed and commercialized, opening up new opportunities to quantify and characterize proteins and peptides in biological matrices (Nolting, Malek, & Makarov, 2017;Vidova & Spacil, 2017;Eliuk & Makarov, 2015). These new mass analyzers have been extensively used by proteomic mass spectrometry scientists, leading to the development of several innovative analytical strategies, including data-dependent acquisition (Kalli, Smith, Sweredoski, & Hess, 2013), data-independent acquisition (DIA) (Sajic, Liu, & Aebersold, 2015), SWATH-MS (Anjo, Santa, & Manadas, 2017) and more recently, SCOUT-MRM (Rougemont et al, 2017).…”