On the Ionization and Ion Transmission Efficiencies of Different ESI-MS Interfaces


The achievable sensitivity of electrospray ionization mass spectrometry (ESI-MS) is largely determined by the ionization efficiency in the ESI source and ion transmission efficiency through the ESI-MS interface. These performance characteristics are difficult to evaluate and compare across multiple platforms as it is difficult to correlate electrical current measurements to actual analyte ions reaching the detector of a mass spectrometer. We present an effective method to evaluate the overall ion utilization efficiency of an ESI-MS interface by measuring the total gas-phase ion current transmitted through the interface and correlating it to the observed ion abundance measured in the corresponding mass spectrum. Using this method, we systematically studied the ion transmission and ionization efficiencies of different ESI-MS interface configurations, including a single emitter/single inlet capillary, single emitter/multi-inlet capillary, and a subambient pressure ionization with nanoelectrospray (SPIN) MS interface with a single emitter and an emitter array, respectively. Our experimental results indicate that the overall ion utilization efficiency of SPIN-MS interface configurations exceeds that of the inlet capillary-based ESI-MS interface configurations.

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The authors thank Dr. Ryan T. Kelly and Dr. Yehia Ibrahim for useful discussions. Portions of this research were supported by the NIH National Cancer Institute (1R33CA155252) and General Medical Sciences (GM103493-12), the Laboratory Directed Research and Development Program at Pacific Northwest National Laboratory (PNNL), and the Department of Energy Office of Biological and Environmental Research Genome Sciences Program under the Pan-omics project. All the experiments were performed in the Environmental Molecular Sciences Laboratory, a US Department of Energy (DOE) national scientific user facility located at PNNL in Richland, Washington. PNNL is a multiprogramming national laboratory operated by Battelle for the DOE under contract DE-AC05-76RLO01830.

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Correspondence to Keqi Tang.

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Cox, J.T., Marginean, I., Smith, R.D. et al. On the Ionization and Ion Transmission Efficiencies of Different ESI-MS Interfaces. J. Am. Soc. Mass Spectrom. 26, 55–62 (2015). https://doi.org/10.1007/s13361-014-0998-5

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  • Electrospray ionization
  • Nanoelectrospray
  • Ion transmission
  • Ionization efficiency
  • ESI emitter array