Laser-desorption mass spectrometry/mass spectrometry and the mechanism of desorption ionization

Zakett, D.; Schoen, Alan; Cooks, R. Graham; Hemberger, P. H.

doi:10.1021/ja00395a086

Cited by 92 publications

(31 citation statements)

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“…A CW C 0 2 laser, if focussed onto a sample for a sufficient time, produces ions, but the delay time between the start of laser irradiation and the emission of ions is on the order of hundreds of milliseconds [9]. High-powered pulsed C 0 2 [10] and Nd-YAG (1.06 pm) [11][12][13] lasers have also been used to pro duce ions from organic surfaces. The production of ions by IR radiation was shown to be caused by adduct ion formation.…”

Section: Introductionmentioning

confidence: 99%

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

Beavis

Lindner

Grotemeyer

et al. 1988

Zeitschrift Für Naturforschung A

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I n f r a r e d D e s o r p tio n o f N e u t r a l M o le c u le s E m b e d d e d in T r a n s p a r e n t M a tr ic e s R.C. Beavis, J. Lindner, J. Grotemeyer, and E.W. Schlag Institut für Physikalische und Theoretische Chemie, Technische Universität München Z. Naturforsch. 43a, 1083Naturforsch. 43a, -1090Naturforsch. 43a, (1988; received July 25, 1988 The desorption of intact molecules by pulsed IR irradiation is shown to depend on the IR absorption of the matrix. IR transparent matrices, such as NaCl or NH4N03, increase the total yield and the shot-to-shot stability of the sample. IR absorbing matrices decrease the yield of intact molecules and increase the amount of pyrolysis products.Using semi-transparent sugar matrices with dipeptide samples, the most intense fragment, i.e. the parent molecule having lost 18 u, is suppressed. This fragment is formed by pyrolysis during IR desorption. Three other prominent fragments are caused by the UV photoionization step.The experimental results suggest that a model involving bulk stresses and strain may be necessary to explain the observations.

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Section: Introductionmentioning

confidence: 99%

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

Beavis

Lindner

Grotemeyer

et al. 1988

Zeitschrift Für Naturforschung A

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“…Taking into account the pioneering works of several research groups in the early 1980s [1][2][3][4][5][6][7][8][9], which investigated direct laser desorption/ionization of organic materials, we first tried to analyze our peptide samples without any substrate by depositing the peptide solution directly on the stainless steel MALDI plate. The results were very promising in terms of sensitivity and detection mass range but the low mass part of the spectra was exhibiting a lot of signals ( Figure 3).…”

Section: Preliminary Ldi Analysesmentioning

confidence: 99%

“…The results gathered from synthetic peptide cocktails indicated that LDI mass spectrometry on silica gel or alumina constitutes a promising complementary method to MALDI in proteomics for peptide mass fingerprinting. [1][2][3][4][5][6][7][8][9] was investigated by Siuzdak and collaborators using porous silicon as the substrate [10]. This desorption/ionization on porous silicon (DIOS) mass spectrometry [10] allows the analysis of various compounds, such as small organic molecules [11], amino acids [12], peptides [13], and fatty acids [14].…”

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confidence: 99%

Laser desorption/ionization mass spectrometry on porous silica and alumina for peptide mass fingerprinting

Shenar

Martinez

Enjalbal

2008

J. Am. Soc. Mass Spectrom.

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We investigated a variant of desorption/ionization on porous silicon (DIOS) mass spectrometry utilizing an aqueous suspension of either porous silica gel or porous alumina (pore size of 60 and 90 Å, respectively). Laser desorption/ionization (LDI) from samples directly deposited on a stainless steel surface without any inorganic substrates was also achieved. Synthetic peptides designed to cover large sequence diversity constituted our model compounds. Sample preparation, including material conditioning, peptide solubilization, and deposition protocol onto standard matrix-assisted laser desorption/ionization (MALDI) probe, as well as ionization source tuning were optimized to perform sensitive reproducible LDI analyses. The addition of either a cationizing agent or an alkali metal scavenger to the sample suspension allowed modification of the ionization output. Comparing hydrophilic silica gel to hydrophobic reversed-phase silica gel as well as increasing material pore size provided further insights into desorption/ionization processes. Furthermore, mixtures of peptides were analyzed to probe the spectral suppression phenomenon when no interfering organic matrix was present. The results gathered from synthetic peptide cocktails indicated that LDI mass spectrometry on silica gel or alumina constitutes a promising complementary method to MALDI in proteomics for peptide mass fingerprinting. [19]. These LDI methods, sometimes referred to as "matrix-free", produce mass spectra that exhibit less matrix ions in the low mass range compared with the chemical noise generated by the organic matrices used in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Such chemical noise that usually pollutes the low mass range of MALDI mass spectra and that may complicate the detection of small molecules is less pronounced in the DIOS mass spectra.Nevertheless, the drawback of such an approach is in the preparation of the silicon material. To present adequate physical properties [20], silicon surfaces are conditioned via a galvanostatic etching procedure from Si wafer to produce pores with nanometer diameters. Commercially available ready-to-use DIOS-chips can also be mounted on modified MALDI plates [20]. Otherwise, silicon powders (5 to 50 nm particle size) were investigated as a substitute to DIOS chips to make the overall sample preparation simpler and safer [18]. Provided that the appropriate powder preparation was performed (including particle etching by HF, oxidation by HNO 3 , and derivatization of the generated SiOH groups), such silicon nanopowder method was found to exhibit the same characteristics as DIOS mass spectrometry.Porous silicon is a material that presents (1) a large active surface and (2) a strong absorbance in the UV range. Such a form of silicon was thus found particularly suitable for LDI mass spectrometry with irradiation at 337 nm, the pore size and the surface chemical nature being the most important parameters as stated by Siuzdak and coworkers in their early publications on DIOS [20...

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“…Evidence for a gas phase ionization mechanism has recently been obtained by these authors [26] and is also reported in the present paper. It has to be added that the appearance of [M +Ag]+ ions of sucrose in the gas phase upon irradiation of a sample layer by short laser pulses of 10 8 W cm -2 [17,27] also points to an ionization mechanism where M and Ag + combine in the gas phase close to the surface because the temperatures required for the release of Ag + from the substrate are by far too high to leave organic molecules intact. For disaccharides there is sufficient experimental evidence of thermal evaporation of intact molecules under appropriate conditions of chemical ionization [28].…”

Section: Introductionmentioning

confidence: 99%

Cationization by Alkali Ion Attachment in Laser Desorption Mass Spectrometry

Stoll

Röllgen

1982

Zeitschrift Für Naturforschung A

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The formation of quasimolecular ions by alkali ion attachment in laser desorption mass spectrometry has been investigated by using a CW CO2 laser. For molecules such as sucrose the desorption of preformed ions could be excluded. Evidence is presented for the ionization by alkali ion attachment in the gas phase. Quasimolecular ions of organic salts were found to result from cationization reactions in the gas phase and from surface reactions. Very fast cation exchange reactions have been discovered for salts and acids impinging on alkali ion emitting surfaces.

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Laser-desorption mass spectrometry/mass spectrometry and the mechanism of desorption ionization

Cited by 92 publications

References 1 publication

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

Infrared Desorption of Neutral Molecules Embedded in Transparent Matrices

Laser desorption/ionization mass spectrometry on porous silica and alumina for peptide mass fingerprinting

Cationization by Alkali Ion Attachment in Laser Desorption Mass Spectrometry

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