Ru(II) polypyridine complexes: photophysics, photochemistry, eletrochemistry, and chemiluminescence

Iterative partial equalization of orbital electronegativity – a rapid access to atomic charges

Protein and polymer analyses up to m/z 100 000 by laser ionization time-of-flight mass spectrometry

Advances in the development of novel cobalt Fischer-Tropsch catalysts for synthesis of long-chain hydrocarbons and clean fuels.

Matrix-assisted ultraviolet laser desorption of non-volatile compounds

Studies of nickel-tungsten-alumina catalysts by x-ray photoelectron spectroscopy

Surface spectroscopic characterization of manganese/aluminum oxide catalysts

A surface study of cobalt-molybdena-alumina catalysts using x-ray photoelectron spectroscopy

Solvent effects on the fluorescence of 1-(dimethylamino)-5-naphthalenesulfonic acid and related compounds

The main problems associated with matrix-assisted laser desorption/ionization (MALDI) quantitative analysis are poor shot-to-shot reproducibility, crystal inhomogeneity, signal degradation, and data acquisition system nonlinearity. These problems are addressed in this paper. The instrumental setup was modified to obtain required linearity and measurement accuracy over a dynamic range of 10 3 . To homogenize the crystal structure, ferulic acid (FA) and fucose were used to form a binary matrix. The optimum molar ratio was analyte/FA/glucose=1:5000: 5000. 2,5-Dihydroxybenzoic acid (DHB), glucose, and 5-methoxysalicylic acid (MSA) were used to form a multicomponent matrix; the optimal analyte/DHB/glucose/ MSA molar ratio was 1:10 4 :(3×10 3 -1×10 4 ):500. Another preparation method that worked particularly cell with DHB involved accelerated drying in high-flow nitrogen at root temperate. Application of these methods rye significant enhancement in spectral reproducibility, signal intensity, and mass resolution. A relative stantard deviation of 6-12% was obtained with a mass resolution of 350-400 (fwhm) at 6000 Da. The FA and DHB comatrices were compared with various matrices and a standard preparation of DHB and FA. The comatrices showed a ca. 50% increase in signal intensity, a 300% decrease in relative standard deviation, and a 30-40% higher resolution. In addition, the use of comatrices resulted in less signal degradation as a function of the number of laser shots in the same location. The visual and spectral differences in crystal structure between FA and DHB both with and without comatrices are illustrated. The laser power was optimized to avoid high abundance of cluster ions and to increase molecular signal. Based on the data presented, an analytical protocol for MALDI quantitative analysis was developed

Improvement of signal reproducibility and matrix/comatrix effects in MALDI analysis

David M. Hercules

Papers

Studies of nickel-tungsten-alumina catalysts by x-ray photoelectron spectroscopy

Surface spectroscopic characterization of manganese/aluminum oxide catalysts

A surface study of cobalt-molybdena-alumina catalysts using x-ray photoelectron spectroscopy

Solvent effects on the fluorescence of 1-(dimethylamino)-5-naphthalenesulfonic acid and related compounds

Improvement of signal reproducibility and matrix/comatrix effects in MALDI analysis