QuantIFIcatIon BY ImagIng MS UsIng TIssue CaLIBratIon StanDarDs

Quantitative analysis of administered drugs in biological tissues is essential for understanding the mechanisms underlying their e cacy or toxicity. Imaging mass spectrometry (IMS) may allow the quanti cation of targeted drugs in tissue sections along with the visualization of their spatial distribution. In this study, surrogate tissue-based calibration standards were prepared to quantify a small molecule drug (S-777469 or raclopride) in tissue sections of mice administered with the drug, followed by analysis with a linear ion trap mass spectrometer equipped with a matrix-assisted laser desorption/ionization (MALDI) source. e distribution of the drugs in the dissected organs was clearly visualized by MALDI-IMS. e drug concentration determined using the calibration standards prepared for MALDI-IMS analysis was highly consistent with that determined by liquid chromatography-tandem mass spectrometry, and the quanti cation in multiple organs was enabled. e results of this study show that MALDI-IMS can be used to quantify small molecule drugs in biological tissue sections using surrogate tissue-based calibration standards.