Shimadzu Corporation 1 article published in JoVE Biochemistry Sample Preparation for Probe Electrospray Ionization Mass Spectrometry Sen Takeda1, Kentaro Yoshimura1, Hiroshi Tanihata2 1Department of Anatomy and Cell Biology, University of Yamanashi School of Medicine, 2Shimadzu Corporation This article introduces sample preparation methods for a unique real-time analytical method based on the ambient mass spectrometry. This method lets us perform real-time analysis of the biological molecules in vivo without any special pretreatments.