Figure 5. The estimated abundance of sn-positional isomers PC 18:0/18:1; PC 18:1/18:0; PC 20:1/16:0; and PC 16:0/20:1 as a percentage of phosphatidylcholines of composition PC 34:1 in different biological extracts and commercially available synthetic standards.

Isomer contributions are estimated from the normalized product ion abundances in DESI-CID/OzID mass spectra as described in the text. All data points represent an average of at least four technical and, where available, biological replicates (see Supporting Information Table S1). Uncertainties shown represent standard deviation. This graph was generated using spectra acquired using offline and online ozone generation methods (see Methods).