RF transfer lines are designed to receive and selectively inject ions from an ionization source to a reaction chamber or into an ion trap, for example the Omnitrap™. Mass selection is performed with a quadrupole mass filter equipped with an off-axis detector. On-axis transmission and off-axis detection are supported by fast switching electronics. The transfer line accommodates Fasmatech’s intermediate pressure ion optical solutions including a hybrid RF ion guide and a temperature-controlled ion funnel.