Click-and-Analyze: Automated Pinpoint Ambient Mass Spectrometry with Sheath-Flow Probe Electrospray Ionization

We report a robotic sheath-flow probe electrospray ionization mass spectrometry system with a new probe design and automated positioning capabilities for pinpoint ambient mass spectrometry. The system integrates a 3-axis Cartesian robot with two cameras: a fixed global camera for coarse positioning and a movable local camera for fine alignment, enabling users to designate sampling spots by mouse-clicking on live images displayed on the graphical user interface. A microcontroller is used for voltage control, current monitoring, and the detection of probe-sample contact. Sampling, transfer, ionization, and cleaning are fully automated under computer control, and the sheath liquid is supplied by a programmable syringe pump to maintain a stable flow rate. The system successfully analyzed aqueous standards, beverages, and water-rich soft materials such as jelly and fruit slices, yielding stable ion signals with negligible carry-over between measurements.