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Chip with twin anchors for reduced ion suppression and improved mass accuracy in MALDI-TOF mass spectrometry
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
KTH, School of Biotechnology (BIO), Theoretical Chemistry.
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2005 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 77, no 3, 827-832 p.Article in journal (Refereed) Published
Abstract [en]

A new sample target for matrix-assisted laser desorption/ionization mass spectrometry is described. The target consists of pairs of elevated hydrophilic anchor surfaces, positioned in proximity onto a microchip. The anchors are used to obtain separate preparations of sample and external standard, while both anchor surfaces are irradiated simultaneously by the laser pulse. Using a standard, based on six peptides, a 2-fold improvement in mass accuracy is observed. Also, ion suppression is significantly reduced. With a one peptide calibration standard, 22 tryptic fragments from a BSA digest are detected using the twin-anchor concept, whereas only 14 fragments are detected when the sample and standard are laser-ablated as a mixture from a conventional anchor target. A volume of similar to30 pL of sample solution of angiotensin I is transferred to the anchor surface, under a thin layer of a perfluorocarbon, to prevent a concentration bias due to evaporation. With this arrangement, a detection limit of 1.5 amol was achieved with a signal-to-noise ratio of 22:1.

Place, publisher, year, edition, pages
2005. Vol. 77, no 3, 827-832 p.
Keyword [en]
assisted-laser-desorption/ionization, sample support, ms, sensitivity, proteins, dna, resolution, silicon
National Category
Analytical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-14499DOI: 10.1021/ac0400966ISI: 000226759000022Scopus ID: 2-s2.0-13344284560OAI: oai:DiVA.org:kth-14499DiVA: diva2:332540
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Improved mass accuracy in MALDI-TOF-MS analysis
Open this publication in new window or tab >>Improved mass accuracy in MALDI-TOF-MS analysis
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Mass spectrometry (MS) is an important tool in analytical chemistry today, particularly in the field of proteomics where identification of proteins is the central activity. The focus in this thesis has been to improve the mass accuracy of MS-analyses in order to improve the possibility for unambiguous identification of proteins.

In paper I a new peak picking algorithm has been developed for Matrix Assisted Laser Desorption/Ionization - Time of Flight - Mass Spectrometry (MALDI-TOF-MS). The new algorithm is based on the assumption that two sets of ions are formed during the ionisation, and that these two sets have different Gaussian-distributed velocity profiles. The algorithm then deconvolutes the spectral peak into two Gaussian distributions, were the narrower of the two distributions is utilized for peak picking. The two-Gaussian peak picking algorithm proved to be especially useful when dealing with weak, distorted peaks.

In paper II a novel chip-based target for MALDI analysis is described. The target features pairs of 50x50 μm anchors in close proximity. Each anchor within a pair could be individually addressed with different sample solutions. Each pair could then be irradiated with the MALDI laser, which allowed ionization to take place on separated anchors simultaneously. This made it possible for us to calibrate analytes with calibration standards that where physically separated from the analyte, but ionized simultaneously. The use of new chip-based MALDI target resulted in a 2-fold reduction of relative mass errors. We could also report a significant reduction of ion suppression. The small size of the anchors provided a good platform for efficient utilization of sample. This resulted in a detection limit of ca. 1.5 attomole of angiotensin I at a S/N of 22:1.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 44 p.
Keyword
Analytical chemistry, MALDI, mass spectrometry, mass accuracy, peak picking, ion formation, proteins, peptides, chip, sample handling, sensitivity., Analytisk kemi
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:kth:diva-313 (URN)91-7178-017-3 (ISBN)
Presentation
2005-05-06, K2, Teknikringen 28, Stockholm, 10:00
Supervisors
Note
QC 20101206Available from: 2005-07-18 Created: 2005-07-18 Last updated: 2010-12-06Bibliographically approved

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