Journal of the Mass Spectrometry Society of Japan

Gas-phase reactions of CH₅⁺, C₂H₅⁺, and C₃H₅⁺ ions with monohalogenated benzenes (PhX=F, Cl, Br, and I) were studied using an ion-trap type of GC/MS at a low chemical-ionization gas pressure of CH₄. The major product channel involves dissociative and non-dissociative proton transfer leading to [M+H-HX+CH₄]⁺=[PhCH₃+H]⁺ for PhF, [M+H]⁺ for PhCl and PhBr, and [M+H-X]⁺=PhH⁺ for PhI. Adduct ions and their decomposition products are also found in reactions of C₂H₅⁺ and C₃H₅⁺. The reaction mechanism is discussed based on the reaction-time dependence of product-ion distributions and semi-empirical calculations of the heat of reaction for each process.

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Imaging mass spectrometry (IMS) has recently been applied to the analysis of drug kinetics using an animal model. Previous reports revealed that IMS could be used to identify the organ where an administered drug was distributed to. In this study, we attempted to visualize the distribution of Famotidine with a higher spatial-resolution in mouse sections using a Mass Microscope that we developed in collaboration with the Shimadzu Corp. In IMS analyses of whole-body sections, Famotidine was found to be distributed largely in the kidney. Moreover, a higher spatial-resolution analysis of the kidney revealed indicated that Famotidine was distributed in the renal pelvis of the kidney. The results suggest that the Famotidine is concentrated in the renal pelvis through the cortex and marrow in the kidney during the excretion process. It can therefore be concluded that a Mass Microscope permits deeper insight into therapeutic and toxicological processes associated with drug administration to be enabled, with a high spatial-resolution.

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