Mass spectrometer with soft ionizing glow discharge and conditioner

An ion source (12, 102) for a mass spectrometer comprising an ionizer (18, 106) receiving an ionizer gas from an ionizer gas supply (16), a conditioner (20) in communication with the ionizer (18, 106), a reactor (22, 110) in communication with the conditioner (20) and adapted for communication with the mass spectrometer, the reactor (22, 110) adapted to receive a sample from a sample supply in communication with the reactor (22, 110), wherein the conditioner (20) is sized to remove fast diffusing electrons from a flow of the ionizer gas from the glow discharge ionizer (18, 106) to the reactor (22, 110).