In the present work, the electric organ of the <i>Torpedo californica</i> was studied using mass spectrometry imaging (MSI) and trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS). Molecular ion density maps (1 x 0.5 mm field of view with 25 µm pixel size) were generated using a MALDI source coupled to a high resolution mass spectrometer (7.0 T Bruker Solarix FTICR-MS). A protocol for sample preparation was developed to preserve the integrity of the sample and it was confirmed by traditional histochemical analysis. MALDI matrices were applied using a home built sublimation chamber and mass assignment was performed with a 3 ppm error tolerance. A total of 87 lipids were identified in the bundle of axons and surrounding electroplaque cells, of which 27 and 29 lipids were characteristic to the axon bundle and electroplaque, respectively. Lipid assignment was further confirmed using TIMS-MS from a liquid surface extraction from the same tissue region. TIMS-MS reveal the presence of multiple isobars for most of the MSI identified characteristic signals, and structural assignment was performed based on the ion-neutral collision cross section differences among the lipid classes. This work provided a workflow for the identification of molecular species from tissue samples, their identification by exact mass (formula) and structural assignment using ion-neutral collision cross section.

Mass spectrometry imaging of the <i>Torpedo californica</i> electric organ using MALDI-FT-ICR MS

249th National Meeting (2015)

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Mass spectrometry imaging of the Torpedo californica electric organ using MALDI-FT-ICR MS