113
MALDI TIMS imaging of a whole body mouse pup tissue was used to demonstrate TIMS capabilities. Positive ion mode TIMS lipid images were collected with
a 50 μm spatial resolution and utilizing a 400 ms EFG scan time (Fig. 7.3). The
extracted ion mobilogram for a single m/z value showed two different ions resolved
across the tissue. One ion was detected throughout the animal but had lower intensity within the brain and brain stem. Conversely, the isobar was abundant within the
brain, spine, and intestines. These ions can be differentiated with TIMS separation.
Although these ions are not isomers, they require very high resolving power if they
are to be resolved by a mass analyzer. High-field FTMS platforms require long scan
times (~1.5–3 s) for the necessary resolving power, making the experiment impractical for most imaging applications. This example highlights the power of TIMS
separations and ion mobility in general for imaging experiments to improve specificity and molecular coverage in direct tissue analysis.
Fig. 7.3 Ion mobility IMS of a whole body mouse pup tissue collected at 50 μm spatial resolution
and a 400 ms TIMS scan time. (a–c) Each panel highlights the positive ion mode images from
selected mobility ranges for m/z 756.5517 and only one peak is detected in the selected mass window (orange) while multiple peaks are observed in the extracted ion mobilogram. (a) Ion image
taken from 1/K0 1.45–1.53, is dominated by the higher intensity [PC(32:0) + Na]
+ similar to
results from a non-ion mobility IMS experiment.(b) [PC(34:3) + H]
+ is found throughout the tissue
except the brain and spinal cord. (c) [PC(32:0) + Na]
+ localizes in the brain, spine and intestines.
(Adapted with permission from Ref. [17]. Copyright 2019 American Chemical Society)
7 Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry…
MALDI TIMS imaging of a whole body mouse pup tissue was used to demonstrate TIMS capabilities. Positive ion mode TIMS lipid images were collected with
a 50 μm spatial resolution and utilizing a 400 ms EFG scan time (Fig. 7.3). The
extracted ion mobilogram for a single m/z value showed two different ions resolved
across the tissue. One ion was detected throughout the animal but had lower intensity within the brain and brain stem. Conversely, the isobar was abundant within the
brain, spine, and intestines. These ions can be differentiated with TIMS separation.
Although these ions are not isomers, they require very high resolving power if they
are to be resolved by a mass analyzer. High-field FTMS platforms require long scan
times (~1.5–3 s) for the necessary resolving power, making the experiment impractical for most imaging applications. This example highlights the power of TIMS
separations and ion mobility in general for imaging experiments to improve specificity and molecular coverage in direct tissue analysis.
Fig. 7.3 Ion mobility IMS of a whole body mouse pup tissue collected at 50 μm spatial resolution
and a 400 ms TIMS scan time. (a–c) Each panel highlights the positive ion mode images from
selected mobility ranges for m/z 756.5517 and only one peak is detected in the selected mass window (orange) while multiple peaks are observed in the extracted ion mobilogram. (a) Ion image
taken from 1/K0 1.45–1.53, is dominated by the higher intensity [PC(32:0) + Na]
+ similar to
results from a non-ion mobility IMS experiment.(b) [PC(34:3) + H]
+ is found throughout the tissue
except the brain and spinal cord. (c) [PC(32:0) + Na]
+ localizes in the brain, spine and intestines.
(Adapted with permission from Ref. [17]. Copyright 2019 American Chemical Society)
7 Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry…