We’ve developed high resolution mass spectrometry imaging instrument, modifying commercial FTICR-MS with in-house build vacuum MALDI ion source. With this instrument one can acquire more than 10,000 mass spectra sequentially from small region of plant tissues glued on small slide glass. Several thousands of peaks were then picked from each spectrum, and then, line spectra were converted into imzML formatted data cube.
The imzML formatted data cube was then thin sliced according to m/z axis to make spatial map of molecules which have same m/z. When we acquired mass spectrum with the resolution higher than 10,000, the typical mass bin size the make spatial map decreases to 0.01 or less. To investigate huge number of maps to find molecules showing similar / different spatial distribution, human eye inspection is impossible to be used. When we want to see profile mass spectra without peak picking, we need to access several hundred GB data cube file. There was no software to allow to work with such huge data file.
To support the analysis of high resolution mass data cube, we’ve developed in-house software “LabMSI”. This software was developed using LabView released from National Instruments Corp. With LabMSI, one can access profile imzML file over 100GB to calculate average mass spectrum and pick peaks from average spectrum to make spatial maps corresponding to picked peaks automatically. Also one can define several ROI (Region of Interest) regions to investigate differences in average spectra of ROI. LabMSI runs on both of Windows and MacOS.
This work was supported by MEXT Japan Grant-in-Aid for Scientific Research, Perceptive Plants.