Raster Mass Spectrometry Imaging

Kidness et al. (29) characterized laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-MS) for imaging of biological tissues in terms of precision. Precisions for thin sections of sheep liver reached 27-59% (raster scan) and 9-47% (line scan) RSD for copper, whereas the precision for zinc was significantly better, 8-18% (raster scan) and 4-21% (line scan) RSD. 

The matrix-coated section is imaged by MALDI mass spectrometry by rastering the laser every 40 p,m in reflectron mode, using a mass range of 500-3,100 m/z see Note 11, Fig. 24.2b). 

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). 

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