Laser desorption time-of-flight mass spectrometry of high mass molecules

Tabet, Jean Claude; Cotter, Robert J.

doi:10.1021/ac00273a028

Cited by 87 publications

(37 citation statements)

References 27 publications

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“…Even considered that the terms "thermal" and "equilibrium process" are used with somewhat different meanings by different authors, the fundamental questio remains. Observation of "non volatile", large organic parent molecular ions with relative molecular masses above 1000 [18,21,22,29,31,36)and often very limited fragmentation supports the notion of a nonequilibrium process.Ver little is on the other hand known about the true volatility of most substances investigated and some of the improvements in the range of detected large ions also result from increased sensitivities of the instruments used. The prolonge ion emission over tens of microseconds as reported by COTTER(17, 18J, on the other hand, seems to rather support a therma1 model.…”

Section: Mechanisms Of Laser Desorptionmentioning

confidence: 73%

“…This pulse structure may be important for the interpretation of some results, particularly the ones obtained with TOF instruments and delayed drawout pulse. About half of the published work has been done with pulsed CO 2 -lasers at 10.6 ~m wavelength [13,16,17,18,30,31,381, the other half with short UV-laser pulses (quadrupled Nd-YAG at 265 nmr20 -29, 39], excimer lasers at 193 nm or 248 nm[l, 3, 7, 281, dye-laser [28,35]). Both wavelength ran£es in the far infrared and far ultraviolet offer the possibility of resonant excitation of respectively vibrational or electronic transitions.…”

Section: Techniques Of Laser Desorptionmentioning

confidence: 99%

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Laser Desorption Mass Spectrometry. A Review

Hillenkamp

1986

Springer Series in Chemical Physics

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Section: Mechanisms Of Laser Desorptionmentioning

confidence: 73%

Section: Techniques Of Laser Desorptionmentioning

confidence: 99%

Laser Desorption Mass Spectrometry. A Review

Hillenkamp

1986

Springer Series in Chemical Physics

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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].…”

mentioning

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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“…The short duration of ion currents necessitates trapping of ions with FTMS (79,89,90) or an ion trap detector (ITD), or detection with time-of-flight mass spectrometry (TOF-MS) (82)(83)(84). Detection of (parts of) LD-MS spectra is also possible using a sector-field mass spectrometer with electro-optical array or photoplate detection (110).…”

Section: Laser Desorption Mass Spectrometrymentioning

confidence: 99%