M/Z: 393.067

By writing the four English letters “PNMK” on white paper with a marker pen, and then scanning with a DESI ion source to obtain the scanning result. The signal of the chemical substances on the marker pen used appears on the channel with an m/z value of 322.1918, 323.1953, 546.4010, and etc, from the single cell deconvolution sampling layer class_4. This test data was tested by chuxiaoping from PANOMIX’s R&D laboratory.

Fig. 4 MALDI-MSI data of mouse lung tissue after administration with D9-choline and U13C-DPPC–containing Poractant alfa surfactant (labels administered 12 h prior to tissue collection). Ion images of (A) m/z 796.6856 ([U13C-DPPC+Na]+), (B) m/z 756.5154 [PC32:0+Na]+), and (C) m/z 765.6079 ([D9-PC32:0+Na]+). D: Overlay image of [U13C-PC32:0+Na]+ (red) and [D9-PC32:0+Na]+ (green). Part-per-million (ppm) mass errors are indicated in parentheses. All images were visualized using total-ion-current normalization and using hotspot removal (high quantile = 99%). DPPC = PC16:0/16:0. MSI, mass spectrometry imaging; PC, phosphatidylcholine; U13C-DPPC, universally 13C-labeled dipalmitoyl PC.

Supplementary Figure S8. MALDI-MSI data of mouse lung tissue administered with D9-choline and U 13C-DPPC–containing Poractant alfa surfactant (labels administered 18 h prior to sacrifice). Ion images of (a) m/z 796.6856 ([U13C-DPPC+Na]+), (b) m/z 756.5154 [PC32:0+Na]+ and (c) m/z 765.6079 ([D9-PC32:0+Na]+). (d) Overlay image of [U13C-DPPC+Na]+ (red) and [D9-PC32:0+Na]+ (green). Parts per million (ppm) mass errors are indicated in parentheses. All images were visualised using totalion-current normalisation and using hotspot removal (high quantile = 99%). DPPC = PC16:0/16:0.