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Homogeneous sample preparation for automated high throughput analysis with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

Önnerfjord, Patrik LU ; Ekström, Simon LU ; Bergquist, Jonas; Nilsson, Johan LU ; Laurell, Thomas LU and Marko-Varga, György LU (1999) In Rapid Communications in Mass Spectrometry 13(5). p.315-322
Abstract

This work presents a simple method for obtaining homogeneous sample surfaces in matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) for the automated analysis of peptides and proteins. The sample preparation method is based on applying the sample/matrix mixture onto a pre-deposited highly diluted matrix spot. The pre-deposited crystals act as seeds for the new sample containing crystals which become much smaller in size and more evenly distributed than with conventional methods. This 'seed-layer' method was developed, optimised and compared with the dried-droplet method using peptides and proteins in the 1000-20000 Da range. The seed-layer method increases the surface homogeneity, spot to spot... (More)

This work presents a simple method for obtaining homogeneous sample surfaces in matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) for the automated analysis of peptides and proteins. The sample preparation method is based on applying the sample/matrix mixture onto a pre-deposited highly diluted matrix spot. The pre-deposited crystals act as seeds for the new sample containing crystals which become much smaller in size and more evenly distributed than with conventional methods. This 'seed-layer' method was developed, optimised and compared with the dried-droplet method using peptides and proteins in the 1000-20000 Da range. The seed-layer method increases the surface homogeneity, spot to spot reproducibility and sample washability as compared with the commonly used dried-droplet method. This methodology is applicable to α-cyanohydroxycinnamic acid, sinapinic acid and ferulic acid, which all form homogeneous crystal surfaces. Within-spot variation and between-spot variation was investigated using statistics at a 95% confidence level (n = 36). The statistical values were generated from more than 5000 data points collected from 500 spectra. More than 90% of the sample locations results in high intensity spectra with relatively low standard deviations (RSDs). Typically obtained data showed an RSD of 19-35% within a sample spot as well as in-between spots for proteins, and an RSD of ≤50% for peptides. Linear calibration curves were obtained within one order of magnitude using internal calibration with a point-RSD of 3% (n = 10). The sample homogeneity allows mass spectra (average of 16 laser shots) to be obtained on each individual sample within 15 sec, whereby a 100 spot target plate can be run in 25 min. High density target plates using the seed-layer method were prepared by spotting ≃100 picoliter droplets onto the target, resulting in sample spots ≤500 μm in diameter using a flow-through piezo-electric microdispenser. By using this automated sample preparation step lower standard deviations are obtained in comparison to manually prepared samples.

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author
organization
publishing date
type
Contribution to journal
publication status
published
in
Rapid Communications in Mass Spectrometry
volume
13
issue
5
pages
315 - 322
publisher
John Wiley & Sons
external identifiers
  • Scopus:0033029128
ISSN
0951-4198
DOI
10.1002/(SICI)1097-0231(19990315)13:5<315::AID-RCM483>3.0.CO;2-C
language
English
LU publication?
yes
id
9461390b-8c16-4ca8-aac5-ccac693f4d37
date added to LUP
2016-10-14 11:36:52
date last changed
2016-11-30 17:14:17
@misc{9461390b-8c16-4ca8-aac5-ccac693f4d37,
  abstract     = {<p>This work presents a simple method for obtaining homogeneous sample surfaces in matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) for the automated analysis of peptides and proteins. The sample preparation method is based on applying the sample/matrix mixture onto a pre-deposited highly diluted matrix spot. The pre-deposited crystals act as seeds for the new sample containing crystals which become much smaller in size and more evenly distributed than with conventional methods. This 'seed-layer' method was developed, optimised and compared with the dried-droplet method using peptides and proteins in the 1000-20000 Da range. The seed-layer method increases the surface homogeneity, spot to spot reproducibility and sample washability as compared with the commonly used dried-droplet method. This methodology is applicable to α-cyanohydroxycinnamic acid, sinapinic acid and ferulic acid, which all form homogeneous crystal surfaces. Within-spot variation and between-spot variation was investigated using statistics at a 95% confidence level (n = 36). The statistical values were generated from more than 5000 data points collected from 500 spectra. More than 90% of the sample locations results in high intensity spectra with relatively low standard deviations (RSDs). Typically obtained data showed an RSD of 19-35% within a sample spot as well as in-between spots for proteins, and an RSD of ≤50% for peptides. Linear calibration curves were obtained within one order of magnitude using internal calibration with a point-RSD of 3% (n = 10). The sample homogeneity allows mass spectra (average of 16 laser shots) to be obtained on each individual sample within 15 sec, whereby a 100 spot target plate can be run in 25 min. High density target plates using the seed-layer method were prepared by spotting ≃100 picoliter droplets onto the target, resulting in sample spots ≤500 μm in diameter using a flow-through piezo-electric microdispenser. By using this automated sample preparation step lower standard deviations are obtained in comparison to manually prepared samples.</p>},
  author       = {Önnerfjord, Patrik and Ekström, Simon and Bergquist, Jonas and Nilsson, Johan and Laurell, Thomas and Marko-Varga, György},
  issn         = {0951-4198},
  language     = {eng},
  number       = {5},
  pages        = {315--322},
  publisher    = {ARRAY(0x80a81a0)},
  series       = {Rapid Communications in Mass Spectrometry},
  title        = {Homogeneous sample preparation for automated high throughput analysis with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry},
  url          = {http://dx.doi.org/10.1002/(SICI)1097-0231(19990315)13:5<315::AID-RCM483>3.0.CO;2-C},
  volume       = {13},
  year         = {1999},
}