An apparatus and method for generating ions from an aerosol and transferring the ions into a mass analyzer. In the apparatus and method, an aerosol beam is generated, the aerosol beam is directed to a spatial volume outside the mass analyzer, particles in the aerosol beam are ionized to produce the ions, and the ions are collected into the mass analyzer. As such the apparatus includes respectively an aerosol beam generator, an ion source generator, and an ion collector.