Imaging mass spectrometry advantage

McLean, J. A., Ridenour, W. B., Caprioli, R. M. (2007) Imaging ion mobility mass spectrometry advantages, challenges, and future prospects. Proceedings of the 55th Annual Meeting of the American Society for Mass Spectrometry, Indianapolis, IN. 

ADVANTAGES AND DRAWBACKS OF IMAGING MASS SPECTROMETRY FOR ANALYSIS OF LIPIDS... 

A modified version of 2DE and gel image analysis, with silver staining, autoradiography, and protein identification and measurement of peptide mass, uses matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) as a rapid and sensitive technique for identifying peptides. MALDI-TOF-MS applies well to protein detection in biological fluids.56 A second advantage of this technique is... 

Currently, there are at least three ionization techniques routinely used in IMS (1) secondary ion mass spectrometry (SIMS), (2) matrix-assisted laser desorption ionization (MALDI), and (3) desorption electrospray ionization (DESI). Each of these ion sources has their own advantages and drawbacks thus, they are usually selected in the context of the imaged sample. In the following text, we provide a concise description of these devices. 

The discussed mass spectrometry-based imaging techniques can be easily implemented for visualization and identification of the compounds separated by TLC. MS-based methods need to be appropriately arranged and optimized before the experiment, which costs a significant amount of time and additional reagents. However, their advantages, such as unambiguous identification of the compounds separated on the plate and visualization of every spot, independently from the quality of the separation itself, make them the perfect choice for detection in combination with the very simple TLC separation technology. 

SIMS instrument designs based around FT-ICR have been able to replicate many of the advantages displayed by such mass filters when applied in mass spectrometry. As an example, mass resolution values of 385,000 have been demonstrated via the single ion method (see Section 5.1.1.1.1) albeit using the 50% definition (Smith et al. 2011). This was reported for molecular secondary ions produced via Cgo primary ion impact. Also demonstrated was the possibility of imaging the organic ions to unprecedented sensitivity and detection limits. This was carried out by synchronizing the pulsed Cgo beam raster with the FT-ICR mass filter detection electronics, i.e. the microprobe method (see Section 5.3.2.2). 

A. 10.3.3 SNMS and RIMS Secondary Neutral Mass Spectrometry (SNMS), also referred to as Sputtered Neutral Mass Spectrometry, is a destructive technique primarily used for examining elemental constituents within solid samples. This technique is closely related to Dynamic SIMS in that an ion beam is used to sputter the solid of interest. The difference lies in the fact that the sputtered neutral population, once ionized, is passed through a mass spectrometer. Ionization is induced via the action of a laser, an electron beam, or plasma (ionization yields vary from 10% for lasers to 1% for plasmas). As the greatest fraction of the sputtered population departs in the neutral state, this methodology provides the advantage of improved detection limits and reduced matrix effects relative to SIMS. Depth resolution can extend to 1 nm. Spatial imaging is generally not carried out. No prior sample preparation is needed, but HV or better conditions are required. 

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