“…Representative DESI-MS and PSI-MS data for the desomorphine precursor, codeine, can be seen in Figure 2. Both ionization sources yield a single parent ion, [codeine + H] + at / 300 (Figures 2(a) and 2(c)), with characteristic fragments at / 183, 215, 225, and 243 corresponding to proposed losses of C 13 H 11 O, C 4 H 7 NO, C 3 H 9 NO, and C 3 H 7 N, respectively (as seen in Figures 2(b) and 2(d)); these MS 2 transitions and associated losses are similar to those reported in the literature [26]. Of note, comparison of the MS spectral intensities obtained for the target analytes using both ionization methods demonstrates higher signal intensity with PSI for both analytes.…”