A High‐Voltage Floating MALDI Source for Ultra‐High‐Resolution Mass Spectrometer

RATIONALE: High-resolution planar electrostatic ion trap (PEIT) requires that injecting ions have a potential energy of 4 keV, so it is essential to couple a high-voltage (HV) floating MALDI source system to its front-end. However, as the system operates within an intermediate-pressure (IP) environment, electrical discharge risks emerge. Consequently, a structural optimization strategy is required to mitigate these risks, ensuring seamless integration of the source with the PEIT. METHODS: SIMION simulations were utilized to optimize pressure and voltage parameters within the IP-MALDI source system for efficient ion transmission. Based on the simulated pressure results, the physical architecture of the system was refined. Specifically, the geometries of the chamber and exhaust tube were optimized to effectively mitigate inherent electrical discharge risks. Finally, the optimized system was integrated into the PEIT front-end to validate its integrated performance and experimental compatibility within the complete instrument platform. RESULTS: Simulation results indicated that at a pressure of 10 Pa, the transmissible m/z range extended from m/z 50 to 20 000. Under this condition, the refined IP-MALDI source system was capable of operating at a 5 kV floating potential, effectively mitigating electrical discharge risks and ensuring seamless compatibility with the PEIT. Experimental validation via the PEIT platform achieved a detectable range of m/z 89-9500, confirming the feasibility and practical efficacy of the proposed system design. CONCLUSIONS: This study developed an IP-MALDI source system specifically engineered for stable operation under HV floating conditions, successfully meeting the requirements for coupling with the PEIT instrument. Furthermore, this work provides an effective and robust solution for the operation of IP ion source systems at high potentials, thereby facilitating their broader application and further technological advancement.