Table 1. Imaging MS parameters and how they affect data properties.
Parameters of imaging MS | Affected aspects and data properties | |
---|---|---|
Sample preparation | MALDI matrix (e.g., DHB, DAN) | Desorption and ionization (and hence detectable molecular classes), spatial resolution (but not critically), sensitivity |
Solvent (e.g., acetonitrile) | Desorption and ionization, sensitivity | |
Source | Source type (e.g., MALDI, DESI, SIMS, IR-MALDESI) | Desorption and ionization, sensitivity (and thus the number of ion channels), potentially spatial resolution (and thus the number of pixels) |
Analyzer | Analyzer type (FTICR, Orbitrap, TOF, QTOF) | Strongly affects spectral properties (dimensionality, noise, background, and, in particular, TOF) and molecular ambiguity; affects spatial properties (noise, resolution) to a lesser degree |
Polarity (positive, negative) | Which ions are detected (and hence molecular classes) | |
Mass-resolving power (e.g., 50,000 or 120,000 at 200 m/z) | Critically affects molecular ambiguity (inversely proportional) and data size (proportional) | |
Mass accuracy | Critically affects data quality, molecular ambiguity, and interpretability |
Abbreviations: DAN, 1,5-diaminonapthalene; DESI, desorption electrospray ionization; DHB, 2,5-dihydroxybenzoic acid; FTICR, Fourier transformation ion cyclotron resonance; IR-MALDESI, infrared matrix-assisted laser desorption electrospray ionization; MALDI, matrix-assisted laser desorption/ionization; MS, mass spectrometry; QTOF, quadrupole time-of-flight; SIMS, secondary ion mass spectrometry; TOF, time-of-flight.