Article

Study of the desorption/ionization mechanism in electrospray droplet impact secondary ion mass spectrometry.

Clean Energy Research Center, The University of Yamanashi, Takeda, Kofu, Japan.
Rapid Communications in Mass Spectrometry (impact factor: 2.79). 03/2011; 25(5):655-60. DOI:10.1002/rcm.4909 pp.655-60
Source: PubMed

ABSTRACT Electrospray droplet impact (EDI) secondary ion mass spectrometry (SIMS) is a desorption/ionization technique for mass spectrometry in which highly charged water clusters produced from an atmospheric-pressure electrospray are accelerated in vacuum by several kV and impact on the sample deposited on the metal substrate. The abundances of the secondary ions for C(60) and amino acids are measured as a function of the acceleration voltage of the primary charged water droplets. Two desorption/ionization mechanisms are suggested in the EDI ionization processes: low-energy and high-energy regimes. In the low-energy regime, the excess charges in the primary droplets play a role in the formation of secondary ions. In the high-energy regime, samples are ionized by the supersonic collision of the primary droplets with the sample. The yield of secondary ions increases by about three orders of magnitude with increase in the acceleration voltage of the primary droplets from 1.75 kV to 10 kV.

0 0
 · 
0 Bookmarks
 · 
39 Views
  • Article: Peptide polarity and the position of arginine as sources of selectivity during positive electrospray ionisationmass spectrometry
    Daniel A. Abaye, Frank S. Pullen, Birthe V. Nielsen
    [show abstract] [hide abstract]
    ABSTRACT: Electrospray ionisation (ESI) is a selective process and, for similar sized analytes, the intrinsic properties of the molecules affect the ionisation process and their response. This research sets out to determine the effect of some of these properties in peptides: peptide polarity and the presence of arginine at positions 1 and 4 in the amino acid sequence on the ESI response. Six peptides; molecular mass ranges 1.3–1.6 kDa; substance P (SP) and glutamate fibrinopeptide (GFP) and 3.2–3.7 kDa; calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP), glucagon-like peptide 1 (GLP1) and defensin human neutropeptide 2 (DHNP2), were investigated. We have demonstrated that in positive ESI, for similar sized peptides and the same charge state, the responsiveness is in the order: Peptides with N or C terminal arginine > most non-polar peptides > least non-polar peptides. Therefore, arginine at the terminal position is a source of selectivity. Data from matrix-assisted laser desorption ionisation (MALDI) analysis supports that of the ESI experiments: Peptides with a terminal arginine residue generated higher signal intensities. Our observations extend our understanding of the ESI process and provide a rational approach to optimising sensitivity of electrospray conditions where a narrow mass range of peptides are poorly chromatographically resolved. This information will provide for a more effective method development process, especially during label-free quantitative determination of peptides extracted in solution. Copyright © 2011 John Wiley & Sons, Ltd.
    Rapid Communications in Mass Spectrometry 01/2011; 25:3597–3608. · 2.79 Impact Factor
  • Source
    Article: Peptide polarity and the position of arginine as sources of selectivity during positive electrospray ionisationmass spectrometry
    Daniel A. Abaye, Frank S. Pullen, Birthe V. Nielsen
    [show abstract] [hide abstract]
    ABSTRACT: Electrospray ionisation (ESI) is a selective process and, for similar sized analytes, the intrinsic properties of the molecules affect the ionisation process and their response. This research sets out to determine the effect of some of these properties in peptides: peptide polarity and the presence of arginine at positions 1 and 4 in the amino acid sequence on the ESI response. Six peptides; molecular mass ranges 1.3–1.6 kDa; substance P (SP) and glutamate fibrinopeptide (GFP) and 3.2–3.7 kDa; calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP), glucagon-like peptide 1 (GLP1) and defensin human neutropeptide 2 (DHNP2), were investigated. We have demonstrated that in positive ESI, for similar sized peptides and the same charge state, the responsiveness is in the order: Peptides with N or C terminal arginine > most non-polar peptides > least non-polar peptides. Therefore, arginine at the terminal position is a source of selectivity. Data from matrix-assisted laser desorption ionisation (MALDI) analysis supports that of the ESI experiments: Peptides with a terminal arginine residue generated higher signal intensities. Our observations extend our understanding of the ESI process and provide a rational approach to optimising sensitivity of electrospray conditions where a narrow mass range of peptides are poorly chromatographically resolved. This information will provide for a more effective method development process, especially during label-free quantitative determination of peptides extracted in solution. Copyright © 2011 John Wiley & Sons, Ltd
    Rapid Communications in Mass Spectrometery. 01/2011; 25:3597–3608.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

amino acids
 
atmospheric-pressure electrospray
 
charged water clusters
 
desorption/ionization mechanisms
 
desorption/ionization technique
 
EDI ionization processes
 
Electrospray droplet impact
 
excess charges
 
high-energy regime
 
high-energy regimes
 
low-energy regime
 
mass spectrometry
 
metal substrate
 
orders
 
primary droplets
 
samples
 
secondary ions
 
secondary ions increases
 
supersonic collision
 
water droplets
 

Daiki Asakawa