Ionization and transmission efficiency in an electrospray ionization—mass spectrometry interface
- 951 Downloads
The ionization and transmission efficiencies of an electrospray ionization (ESI) interface were investigated to advance the understanding of how these factors affect mass spectrometry (MS) sensitivity. In addition, the effects of the ES emitter distance to the inlet, solution flow rate, and inlet temperature were characterized. Quantitative measurements of ES current loss throughout the ESI interface were accomplished by electrically isolating the front surface of the interface from the inner wall of the heated inlet capillary, enabling losses on the two surfaces to be distinguished. In addition, the ES current lost to the front surface of the ESI interface was spatially profiled with a linear array of 340-µm-diameter electrodes placed adjacent to the inlet capillary entrance. Current transmitted as gas-phase ions was differentiated from charged droplets and solvent clusters by measuring sensitivity with a single quadrupole mass spectrometer. The study revealed a large sampling efficiency into the inlet capillary (>90% at an emitter distance of 1 mm), a global rather than a local gas dynamic effect on the shape of the ES plume resulting from the gas flow conductance limit of the inlet capillary, a large (>80%) loss of analyte ions after transmission through the inlet arising from incomplete desolvation at a solution flow rate of 1.0 µL/min, and a decrease in analyte ions peak intensity at lower temperatures, despite a large increase in ES current transmission efficiency.
KeywordsReserpine Transmission Efficiency Solution Flow Rate Charged Droplet Capillary Inlet
- 4.Shen, Y.; Zhang, R.; Moore, R. J.; Kim, J. K.; Metz, T. O.; Hixson, K. K.; Zhao, R.; Livesay, E. A.; Udseth, H. R.; Smith, R. D. Automated 20 Kpsi RPLC-MS and MS/MS with Chromatographic Peak Capacities of 1,000–1,500 for and Capabilities for Proteomics and Metabolomics. Anal. Chem. 2005, 77, 3090–3100.CrossRefGoogle Scholar
- 7.Kebarle, P.; Tang, L. From Ions in Solution to Ions in the Gas Phase—The Mechanism of Electrospray Mass Spectrometry. Anal. Chem. 1993, 65, A972-A986.Google Scholar
- 17.Cole, R. B., Ed. Electrospray Ionization Mass Spectrometry: Fundamentals, Instrumentation, and Applications. John Wiley & Sons: New York, 1997.Google Scholar
- 30.Gerlich, D. State-Selected and State-to-State Ion-Molecule Reaction Dynamics. Part 1. Experiment. Wiley: New York, 1992; 1–76.Google Scholar