Supporting Information
Data Processing for 3D Mass Spectrometry Imaging
Xingchuang Xiong 1,2,3 , Wei Xu3, Livia S. Eberlin4, Justin M. Wiseman5, Xiang Fang2, You Jiang 2, Zejian Huang 2, Yukui Zhang 1, R. Graham Cooks4, Zheng Ouyang 3*
1 School of Life Scienceļ¼Beijing Institute of Technology, Beijing 100081, China
2 National Institute of Metrology Beijing 100013, China
3 Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, US
4 Department of Chemistry, Purdue University, West Lafayette, IN 47097, US
5 Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, US
*Corresponding Author:
Prof. Zheng Ouyang
Weldon School of Biomedical Engineering
Purdue University
West Lafayette, IN 47907
Email:
Phone: 765-494-2214
Comparison between bin method and peak detection and alignment method
The peak detection and peak alignment method applies statistical analysis on the shapes and the locations of the maxima in the profile to identify the peaks in raw spectra, as shown in Figure S1a. This method reserves the resolution of the raw spectra and improves the mass accuracy for identified peaks since the m/z value of a peak is determined based on the statistical analysis of all spectra recorded for an entire tissue section, as shown in Figure 1b and c.
Using the bin method, a peak shift up to half of the bin width might occur, as shown by Figure S1 c and d. To reserve the high mass accuracy of the raw data, finer bin windows must be used to identify the maxima in the peak profile, viz. the positions of the peaks, as shown in Figure S1e. As a result, a large number of peaks are registered for one single peak profile (Figure S1f). Some treatment based on the statistical analysis of these binned peaks is still required before further data processing.
Figure S1. a) The profile of the peaks in raw data recorded using LTQ. b) the peaks identified using peak detection and peak alignment. c) Bin method applied with a bin width of 1 Th and d) the peaks identified accordingly. e) Bin method applied with a bin width of 0.5 Th and f) the peaks identified accordingly.
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