Figure 8.

Electrospray ionization in positive ion mode MS spectra (full scan) (A, C) and the ESI-MS/MS spectra of m/z 936.5 [M+Na]⁺ peak, where M is RAP (B, D) from the release extracts of crystalline RAP (free drug) collected at day 9 from in vitro release following dialysis method. Liquid chromatography MS/MS detection at m/z 936.5 on extracts was performed at 12.38 minutes (A, B) and 12.57 minutes (C, D), corresponding with the retention time of the peak and the shoulder usually observed in the chromatograms. In both cases, ion with m/z 936.5 was observed within these peaks (A, C) with similar MS/MS fingerprints (B, D), confirming that these species are likely isomers of RAP.