Figure 3. DESI-CID/OzID mass spectra obtained from the [M+Na]⁺ ions at m/z 782 corresponding to PC 34:1 isomers from (a) egg yolk, (b) cow perinephric adipose, (c) cow kidney medulla and (d) cow ocular lens.

Peaks indicative of the sn-positional isomers PC 16:0/18:1 (*) and PC 18:1/16:0 (▪) are marked as indicated. Spectra acquired using online ozone generation (see Methods).