Lenses or No Lenses? A Study of Ion Transfer Efficiency at Interfaces in a Lens-free Triple Quadrupole MS Abstract Gas collisions may increase the efficiency of a lens-free, RF-only interface between a quad and collision cell but they significantly reduce the efficiency of lens-based interfaces. Collision pressure, energy, and mass have little influence to the ion transfer efficiency of a lens-free interface while they significantly change the efficiency of lens-based interfaces Overall, a lens-free, RF-only interface is not just simpler and more robust than a lens-based interface but it also provides significantly higher efficiency.