Laser adsorption ionization

MALDI-TOF Matrix-assisted laser adsorption/ionization time-of-flight... 

Gridin, V.V., Litani-Barzilai, I., Kadosh, M., Schechter, I. (1998) Determination of aqueous solubility and surface adsorption of polycyclic aromatic hydrocarbons by laser multiphoton ionization. Anal. Chem. 70, 2685-2692. 

This proposal describes the development of a new, systematic approach for qualitatively and quantitatively studying surface-biomolecule interactions by matrix-assisted laser desorption ionization (MALDl) mass spectrometry (MS). This methodology is being developed because of the profound importance that surface-biomolecule interactions play in applications where biomaterials come into contact with complex biological fluids, it can readily be shown that undesired reactions occurring in response to surface-biomolecule contact (protein adsorption, biofouling, immune response activation, etc.) lead to enormous economic and human costs. Thus, the development of analytical methodologies that allow for efficient assessment of the properties of new biomaterials and/or the study of detailed fundamental processes initiated upon surface-biomolecule contact are of critical value ... 

The SELDI instrument is a laser desorption ionization mass spectrometer capable of ionizing proteins from an adsorptive surface, or biochip. The instrument has a customized carriage to feed biochips into what is essentially a MALDI instrument... 

The polypeptide polyalanine was synthesized1 and characterized by Matrix Assisted Laser Desorption Ionization (MALDI) and amino acid hydrolyses. Monolayers of either l- or D-polyalanine polypeptides, in the form of an a-helix, were prepared by self-assembly on a borosilicate slide that was coated with a 200-300 nm thick gold film (Metallhandel Schroer Gmbh). Prior to the adsorption, the gold slides were annealed by flame and only then inserted into a 1 mM peptide solution of... 

Matrix-assisted laser desertion ionization (MALDI) was first described by Karas and Hillenkamp in 1988 [469]. At that time it was a revolutionary method for the ionisation and analysis of large biomolecules. Now many more MS methods have been devised, but the analysis of complete protein masses is still only possible by MALDI [470]. With MALDI, a matrix (crystals of small organic molecules) with a small amount of analyte is ionised by a short laser pulse at a wavelength close to the adsorption band of the matrix molecules. This produces predominantly singly charged molecular ions, which are detected by the TOE spectrometer. The ana-... 

In 1993, Hutchens and co-workers described surface-enhanced laser desorption/ionization (SELDI) technique, an affinity technology, which has progressed over the last decade to become a powerful analytical, an on-plate approach (Hutchens and Yip 1993). SELDI is a distinctive form of laser desorption/ionization (LDI) mass spectrometry in which the EDI probe plays an active role in the homogenization, preconcentration, amplification, purification, extraction, enrichment digestion, derivatization, synthesis, separation, and detection with complementary techniques, prior to the desorption and ionization of the analytes by MALDI (Merchant and Weinberger 2000). The principle of this approach is very simple. Biomolecules are captured by adsorption, partition, electrostatic interaction, or affinity chromatography on a solid-phase protein chip surface. Although SELDI provides a unique sample preparation platform, it is similar to MALDI-MS in that a laser... 

Spriestersbach KH, Rode K, Pasch H. Matrix-assisted laser desorption/ionization mass spectrometry of synthetic polymers, 7. Analysis of fatty alcohol ethoxylates by coupled liquid chromatography at the critical point of adsorption and MALDI-TOF mass spectrometry. Macromol Symp 2003 193 129-41. 

Macromolecular Materials and Engineering 286, No.3, 30th March 2001, p.161-7 MATRIX-ASSISTED LASER DESORPTION/ IONIZATION MASS SPECTROMETRY OF SYNTHETIC POLYMERS, 5A. ANALYSIS OF POLY(PROPYLENE OXIDE)S BY COUPLED LIQUID CHROMATOGRAPHY AT THE CRITICAL POINT OF ADSORPTION AND MALDI-TOF MASS SPECTROMETRY Keil C Esser E Pasch H Darmstadt,Deutsches Kunststoff-Institut... 

In field ionization, hydrogen molecules near the tip region are attracted to the tip surface. They either hop around the tip surface or are field adsorbed on it. As the hopping motion and the field adsorption are dynamical phenomena, some of the ionic species detected may also come from field adsorbed states, not necessarily just from the gas phase. On the other hand, in pulsed-laser stimulated field desorption, where gas pressure is very low, of only 1 X 10-8 Torr, gas molecules are thermally desorbed by laser pulses from their field adsorbed and chemisorbed states. When they pass across the field ionization zone some of them are field ionized. The critical ion energy deficit in pulsed-laser stimulated field desorption of a gas is therefore found to be identical to that found in field ionization. In both pulsed-laser stimulated field desorption and field ionization of hydrogen, the majority of ions detected are H3 and H+. 

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