The ZipChip CE Ti interface with nano-ESI ion source (908 Devices, Boston, MA, USA) was installed following the vendor's instructions. The Ti interface was attached to the front end of an Orbitrap Exploris 240 Mass Spectrometer (Thermo Scientific, Bremen, Germany) and an HR chip with a 22 cm long separation channel was used. Before analysis, each AAV sample was diluted 5-fold with peptide BGE (5 µL of sample + 20 µL of peptide BGE) and incubated on a Thermomixer for 15 minutes at 37°C shaking at 500 rpm. Meanwhile the HR Chip was primed with Peptides BGE containing 4% v/v DMSO.