Introducing Samples Directly into Electrospray Ionization Mass Spectrometers by Direct Infusion Using a Nanoelectrospray Interface

Terry D. Lee1, Roger E. Moore1, Denise Keen1

1 Beckman Research Institute of the City of Hope, Duarte, California
Publication Name:  Current Protocols in Protein Science
Unit Number:  Unit 16.8
DOI:  10.1002/0471140864.ps1608s74
Online Posting Date:  November, 2013
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Procedures are described for constructing and using a microscale electrospray interface for direct infusion of samples into mass spectrometers. The sensitivity of the nanospray interface is a result of greatly reducing the flow of sample solution while preserving the analyte signal intensity. The described methodology provides a simple and robust way to analyze individual purified peptide and protein samples, i.e., samples that do not require liquid chromatography separation. Curr. Protoc. Protein Sci. 74:16.8.1‐16.8.7. © 2013 by John Wiley & Sons, Inc.

Keywords: mass spectrometry; nanoelectrospray; microscale electrospray interface

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Table of Contents

  • Basic Protocol 1: Analysis of Peptide and Protein Samples by Direct Infusion Nanoelectrospray
  • Commentary
  • Literature Cited
  • Figures
  • Tables
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Basic Protocol 1: Analysis of Peptide and Protein Samples by Direct Infusion Nanoelectrospray

  • ∼10 pmol/µl suitably prepared peptide or protein sample (free from buffer salts and strong acids; see Commentary)
  • Sample solvent: 50% (v/v) aqueous acetonitrile/1% (v/v) formic acid
  • Nanoelectrospray mount (e.g., Universal Nanoflow Sprayer, cat. no. 70003890), Thermo or mount intended for LC/MS operation (e.g., Universal Nanoflow Sprayer, cat. no. 70003890, Waters)
  • 0.368‐mm diameter platinum wire (see Table 16.8.1 for suppliers)
  • 1‐mm o.d. × 0.75‐mm i.d. × 2‐cm length, tip i.d. 1 ± 0.5 µm, with filament pulled, borosilicate glass needles (see Table 16.8.1 for suppliers or Rae and Levis, , for fabrication)
  • 0.25‐mm o.d. gel‐loading pipet tips (e.g., Eppendorf, cat. no. 022351656; USA Scientific, cat. no. 1022‐8950) and pipettor
  • Electrospray mass spectrometer
Table 6.8.1   MaterialsCommercial Vendors of Nanoelectrospray Components

Company Location Phone Web site
Platinum wire
Alfa Aesar Ward Hill, Mass. 978‐521‐6300
ESPI Metals Ashland, Oreg. 800‐635‐2581
Prepulled glass capillaries
Scientific Instrument Services Ringoes, N.J. 908‐788‐5550
FIVEphoton Biochemicals San Diego, Calif. 800‐462‐4507
World Precision Instruments Sarasota, Fla. 866‐606‐1974
Tritech Research Los Angeles, Calif. 800‐733‐3874
Glass capillary pullers
Harvard Apparatus Holliston, Mass. 800‐323‐2380
Sutter Instrument Company Novato, Calif. 888‐883‐0128
World Precision Instruments Sarasota, Fla. 866‐606‐1974
MicroData Instrument S. Plainfield, N.J. 908‐222‐1717
Vestavia Scientific Birmingham, Ala. 205‐979‐9852
Tritech Research Los Angeles, Calif. 800‐733‐3874
C18 pipet tips
Varian (Omix C18 tips) Walnut Creek, Calif. 866‐377‐0104
Sigma‐Aldrich (Supel‐Tips C18) Bellefonte, Pa. 800‐247‐6628
EMD Milliopore (ZipTip C18) Billerica, Mass. 800‐645‐5476
Thermo Scientific (Pierce C18 Tips) Rockford, Ill. 800‐874‐3723

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Literature Cited

Literature Cited
  Geromanos, S., Freckleton, G., and Tempst, P. 2000. Tuning of an electrospray ionization source for maximum peptide‐ion transmission into a mass spectrometer. Anal. Chem. 72:777‐790.
  Gibson, G.T., Mugo, S.M., and Oleschuk, R.D. 2009. Nanoelectrospray emitters: Trends and perspective. Mass Spectrom. Rev. 28:918‐936.
  Mao, P., Wang, H.T., Yang, P., and Wang, D. 2011. Multinozzle emitter arrays for nanoelectrospray mass spectrometry. Anal. Chem. 83:6082‐6089.
  Rae, K.L. and Levis, R.A. 2004. Fabrication of patch pipets. Curr. Protoc. Neurosci. 26:6.3.1‐6.3.32.
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  Whitehouse, C.M., Dreyer, R.N., Yamashita, M., and Fenn, J.B. 1985. Electrospray interface for liquid chromatographs and mass spectrometers. Anal. Chem. 57:675‐679.
  Wilm, M.S. and Mann, M. 1994. Electrospray and Taylor‐Cone theory, Dole's beam of macromolecules at last? Int. J. Mass Spectrom. Ion Proc. 136:167‐180.
  Wilm, M. and Mann, M. 1996. Analytical properties of the nanoelectrospray ion source. Anal. Chem. 68:1‐8.
  Zhu, Y., Pan, J.Z., Su, Y., He, Q.H., and Fang, Q. 2010. Fabrication of low‐melting‐point alloy microelectrode and monolithic spray tip for integration of glass chip with electrospray ionization mass spectrometry. Talanta 81:1069‐1075.
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