Characterization of complex hydrocarbons in cigarette smoke condensate by gas chromatography-mass spectrometry and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

Gas chromatography-mass spectrometry with electron ionization and positive-ion chemical ionization and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC-TOF-MS) were applied for the characterization of the chemical composition of complex hydrocarbons in the non-polar neutral fraction of cigarette smoke condensates. Automated data processing by TOF-MS software combined with structured chromatograms and manual review of library hits were used to assign the components from GC x GC-TOF-MS analysis. The distributions of aliphatic hydrocarbons and aromatics were also investigated. Over 100 isoprenoid hydrocarbons were detected, including carotene degradation products, phytadiene isomers and carbocyclic diterpenoids. A total of 1800 hydrocarbons were tentatively identified, including aliphatic hydrocarbons, aromatics, and isoprenoid hydrocarbons. The identified hydrocarbons by GC x GC-TOF-MS were far more than those by GC-MS. (C) 2004 Elsevier B.V. All rights reserved.

Enzymatic reaction of the immobilized enzyme on porous silicon studied by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry

Desorption/ionization on silicon mass spectrometry (DIOS-MS) is a matrix-free technique that allows for the direct desorption/ionization of low-molecular-weight compounds with little or no fragmentation of analytes. This technique has a relatively high tolerance for contaminants commonly found in biological samples. DIOS-MS has been applied to determine the activity of immobilized enzymes on the porous silicon surface. Enzyme activities were also monitored with the addition of a competitive inhibitor in the substrate solution. It is demonstrated that this method can be applied to the screening of enzyme inhibitors. Furthermore, a method for peptide mapping analysis by in situ digestion of proteins on the porous silicon surface modified by trypsin, combined with matrix-assisted laser desorption/ionization-time of flight-MS has been developed.

Immobilized metal-ion chelating capillary microreactor for peptide mapping analysis of proteins by matrix assisted laser desorption/ionization-time of flight-mass spectrometry

Peptide mass mapping analysis, utilizing a regenerable enzyme microreactor with metal-ion chelated adsorption of enzyme, combined with matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) was developed. Different procedures from the conventional approaches were adopted to immobilize the chelator onto the silica supports, that is, the metal chelating agent of iminodiacetic acid (IDA) was reacted with glycidoxypropyltrimethoxysilane (GLYMO) before its immobilization onto the inner wall of the fused-silica capillary pretreated with NH4HF2. The metal ion of copper and subsequently enzyme was specifically adsorbed onto the surface to form the immobilized enzyme capillary microreactor, which was combined with MALDI-TOF-MS to apply for the mass mapping analysis of nL amounts of protein samples. The results revealed that the peptide mapping could routinely be generated from 0.5 pmol protein sample in 15 min at 50degreesC, even 20 fmol cytochrome c could be well digested and detected.

Rapid molecular weight determination of recombinant hirudin by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The molecular weight of recombinant hirudin ( rHV-2) was determined rapidly by matrix-assisted laser desorption/ionization time of fight mass spectrometry (MALDI-TOF-MS). The effects of the three types of matrixes were compared and discussed, alpha-cynao-4-hydroxycinnamic acid was proved to be the best matrix. It showed that MALDI-TOF-MS was superior to the traditional method of molecular weight determination of the biological macromolecules. The mass spectrum data proved that the primary structure of rHV-2 was correct and there was no amino acid deletion, mutation and modification in its expression, refolding and purification.

Analysis of poly (arylene phosphonate) cyclic oligomer by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MAIDI-TOF-MS) was used for analysis of poly(arylene phosphonate) cyclic oligomers. A comparison was made by using 1,8,9-dithranol, 2,5-dihydroxybenzoic acid and retinoic acid as the matrix. The result showed that the retinoic acid produced the strongest ion signals under the conditions used. Different salts of metals were used as the cationization agents to examine the effect on the cyclic oligomers. It was found that the salts could produce metal-cyclic oligomer cation spectra and lithium was the stronger one than those of silver so, the suitable matrix and cationization agent for the new cyclic oligmer were obtained. They were very effective for the analysis of poly(arylene phosphonate) cyclic oligomer.

Investigation of a series of synthetic cationic porphyrins using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was used to study a series of synthetic cationic porphyrins as the perchlorate and bromide salts. This work presents the analytical results for the porphyrins obtained using 2,5-dihydroxybenzoic acid (DHB) and 1,8,9-anthratriol as matrices. The selective use of matrix affects ion formation from these porphyrins. By using DHB as the matrix, we not only observed [M - nCIO(4)](+) (n = 1-4) ions, but also obtained [2M - nCIO(4)](+) (n = 2-7) ions from the synthetic cationic porphyrins. The space volume of the side chains (R groups) and the nature of the anions (Br- or CIO4-) affected the relative importance of monomeric and dimeric ions of the porphyrin. The possible mechanisms of desorption and ionization of these cationic porphyrins were also considered in this study. MALDI-TOFMS proved to be a very useful method for obtaining structural information on these synthetic cationic porphyrins. Copyright (C) 1999 John Whey & Sons, Ltd.

Characterization of cyclic arylether ketone (sulfone) containing hexafluoroisopropylidene unit by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

The cyclic aryletherketone( sulfone) oligomers containing hexafluoroisopropylidene unit were characterized by matrix-assisted laser desorption ionization time-of-night mass spectrometry(MALDI-TOF-MS) using Na+ and Ag+ as cationization agents. The affinities of cyclic oligomers to the cation were studied. The analysis result showed that 1,8,9-dithranol, in the presence of silver trifluoroacetate, was very effective for the characterization of cyclic arylether ketone ( sulfone) containing hexafluoroisopropylidene unit.

Determination of purity and molecular weight of calmodulin by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The purity and molecular weight of calmodulin have been determined by means of matrix-assisted laser desorption/ionization time of flight mass spectrometry, and the results have been discussed. The experimental results demonstrate that this method is high sensitive and rapid as compared with other traditional methods.

Application of matrix-assisted laser desorption/ionization-time of flight-mass spectrometry and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in determining arginine esterase from snake venom

Using matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). The homogeneities and molecular weights of three arginine esterases from snake venom, which possessing therapeutic use in myocardial infarction, were determined and compared, MALDI-TOF-MS is possessed of high accuracy, high sensitivity and rapidity. MALDI-TOF-MS and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) can provide complementary and confirmatory results information. MALDI-TOF-MS can be directly used as an important method for the purification of snake venom complexes successfully.