showing good signal intensity while the intensity of AAV8 appeared lower. This was to some extent also observed in fluorescence traces in Fig. , likely caused by the increased peak width of that par9cular serotype. Other contribu9ng factors could be a higher non-specific adsorp9on of AAV8 to surfaces or lower MS ioniza9on and ion trapping efficiencies when compared to the other two serotypes inves9gated. Nonetheless, the MS signal strength allowed for collec9on of useful mass spectra also for AAV8. Fig. shows the mass spectra corresponding to peaks in A aeer peak integra9on and spectral averaging. In all cases spectra of the earlier elu9ng peak appeared in a m/z region of around 30,000 while spectra from the later elu9ng peak were centered at around 22,500 m/z. Assuming a similar molecular charge aeer MS ioniza9on, the earlier elu9ng peak must contain species of significantly higher molecular mass which can of course be explained by the presence of cargo DNA, adding an addi9onal mass of approximately 0.8 MDa. As was already an9cipated, the complexity of the samples did not allow for deconvolu9on and mass determina9on but indeed for a clear differen9a9on of full and empty capsids, also confirming the elu9on order previously determined based on injec9on of individual full and empty samples (Fig. ). The presented method allows for the pH-gradient separa9on of full and empty capsids of mul9ple AAV serotypes based on MS-friendly anion exchange chromatography. Fluorescence signals can be u9lized to precisely quan9fy full and empty capsid propor9ons while subsequent mass spectrometric interfacing allows for peak assignment. Recently, interfacing of liquid chromatography to CDMS was demonstrated for the first 9me. While na9ve MS did not allow for precise mass determina9on and the dis9nc9on of possibly present forms other than full and empty species, charge detec9on mass spectrometry might very well be capable of this. Whether liquid chromatography and CDMS is feasible for highly heterogeneous macromolecules such as AAVs s9ll needs inves9ga9on, but the founda9on has been laid for the development of more sophis9cated and informa9ve AAV characteriza9on strategies which are based on liquid chromatography and mass spectrometry.