Rapidly Switchable Dual Ion Source Combining ESI with iLTP/Tube Plasma for LC–MS, Multi- ² D LC × LC, and SLIM-IM-MS Applications

High-throughput analysis is becoming increasingly important in liquid chromatography-mass spectrometry coupling to minimize downtime for efficient and cost-effective operations in the analytical laboratory. In response to this need, a dual ion source has been designed to provide two ionization modes under atmospheric conditions: electrospray ionization (ESI) and dielectric-barrier discharge (DBD)-based plasma. This dual ion source allows for the rapid switching of the ionization mode during a chromatographic run. Therefore, substances with different ionization behaviors can be detected within one measurement if their retention times differ. The performance of the dual ion source was evaluated using single- and multidimensional liquid chromatography coupled to a quadrupole-time-of-flight (Q-TOF) mass spectrometer and a structures for lossless ion manipulations ion mobility mass spectrometer to analyze mixed standards and real samples. Most notably, the dual ion source maintained strong ion signals and a stable performance while switching ionization modes during a run. Instrumental limits of detection reached down to the sub 1 nM range for both ESI and DBD. This work describes the design and construction of the dual ion source, which provides electrospray- and plasma-based ionization that can be switched within a chromatographic run.