| 1. |
- Ber, B. Y., et al.
(author)
-
Determination of nitrogen in silicon carbide by secondary ion mass spectrometry
- 2004
-
In: Journal of Analytical Chemistry. - 1061-9348 .- 1608-3199. ; 59:3, s. 250-254
-
Journal article (peer-reviewed)abstract
- The emission of atomic and complex nitrogen ions, which are the main impurity determining the n type conduction of silicon carbide, is investigated. It is shown that, among all the secondary ions of the CxN and SixN kind (x = 0, 1, 2, 3), the (26)(CN)(-) fragment exhibits the highest ion yield. The use of an ion peak with a specified mass as an analytical signal provides a detection limit for nitrogen in SiC at a level of 10(16) cm(-3). This result is attained in measurements at high mass resolution (M/DeltaM = 7500, interference peak (26)(C-13(2))(-)).
|
|
| 2. |
- Chekalin, N. V., et al.
(author)
-
Investigation of evaporation and atomization processes in a variable-pressure electrothermal atomizer by laser spectroscopy using gallium as an example
- 2000
-
In: Journal of Analytical Chemistry. - : Maik Nauka/Interperiodica. - 1061-9348 .- 1608-3199. ; 55:6, s. 561-566
-
Journal article (peer-reviewed)abstract
- A new approach to studying the evaporation and atomization of elements in graphite furnaces has been developed that combines a highly sensitive technique of laser-induced fluorescence and variable-pressure atomization. This approach allows one to work with low concentrations of analytes corresponding to real analytical conditions, to separate concurrent processes of evaporation and atomization, and to determine their parameters. The approach has been used for studying the evaporation and atomization of gallium in isothermal graphite furnaces.
|
|
| 3. |
- Chekalin, N. V., et al.
(author)
-
Studying element vaporization and atomization processes in electrothermal atomizers by laser-excited atomic fluorescence spectrometry: indium, matrix effects
- 2000
-
In: Journal of Analytical Chemistry. - : Maik Nauka/Interperiodica. - 1061-9348 .- 1608-3199. ; 55:10, s. 964-971
-
Journal article (peer-reviewed)abstract
- Indium vaporization and atomization processes were studied in a variable-pressure atomizer by laser-excited fluorescence spectrometry for various analyte masses over a wide range of buffer-gas pressures. It was found that the atomization processes are of intricate nature and depend on the element mass, pressure, and heating rate. Based on the data obtained over a wide range of pressures, individual atomization processes were singled out and their parameters were determined. The effects of KCl and CuCl2 matrices on the kinetics and other characteristics of the processes were investigated. Possible mechanisms of indium vaporization and atomization under various experimental conditions and mechanisms of matrix effects on the analytical signals of indium and gallium are discussed.
|
|
| 4. |
- Gazaryan, I G, et al.
(author)
-
Tobacco peroxidase as a new reagent for amperometric biosensors
- 2005
-
In: Journal of Analytical Chemistry. - : Springer Science and Business Media LLC. - 1608-3199 .- 1061-9348. ; 60:6, s. 558-566
-
Journal article (peer-reviewed)abstract
- The results of testing a new enzyme, anionic tobacco peroxidase (TOP), in various amperometric biosensors are summarized. The biochemical and electrochemical properties of the enzyme are briefly characterized. As compared to the commonly used cationic peroxidase from horseradish roots, TOP exhibits a wider optimum stability pH range, higher stability to inactivation with hydrogen peroxide, and higher efficiency in direct electron-transfer processes. The enzyme immobilized by adsorption on graphite is effective in determining aminophenols and aromatic diamines under flow conditions with a detection limit of 10 nM. Upon immobilization on graphite by incorporation into a get of a redox-active polymer (crosslinked polyvinylimidazole with osmium 4,4'-dimethylbipyridinium chloride), TOP exhibited sensitivity and stability comparable to those of horseradish peroxidase and a wider linearity range. Upon immobilization on a self-assembled thiol monolayer at a gold electrode, TOP was much superior to horseradish peroxidase in the sensitivity of determining hydrogen peroxide, regardless of the charge of the monolayer. Prospects for the further use of the native enzyme and its genetically engineered unglycosylated form are considered.
|
|
| 5. |
- Goloborod'ko, A. A., et al.
(author)
-
Alternative methods for verifying the results of the mass spectrometric identification of peptides in shotgun proteomics
- 2010
-
In: Journal of Analytical Chemistry. - 1061-9348 .- 1608-3199. ; 65:14, s. 1462-1468
-
Journal article (peer-reviewed)abstract
- Database search is the most popular approach used for the identification of peptides in contemporary shotgun proteomics; it utilizes only mass spectrometric data. In this work, we introduce three criteria for the verification of peptide identification; these are based on the analysis of data orthogonal to tandem mass spectra. The first one utilizes chromatographic retention times of peptides. The development of such approaches has been hindered by the relatively low accuracy of retention time prediction algorithms. In this work, we suggest the use of two independent models of the liquid chromatography of peptides, which increase the reliability of the results. The second criterion utilizes the mean number of missed tryptic cleavages per peptide. The third one results from the analysis of the difference between theoretical and experimentally measured peptide masses. The proposed criteria were applied to the tandem mass spectra of tryptic peptides from rat kidney tissue, which were processed by the Mascot search engine. All the criteria showed that Mascot significantly overestimated the reliability of an identification. This conclusion was supported by the PeptideProphet algorithm.
|
|
| 6. |
|
|
| 7. |
- Samgina, T. Yu, et al.
(author)
-
Investigation of skin secretory peptidome of Rana lessonae frog by mass spectrometry
- 2011
-
In: Journal of Analytical Chemistry. - 1061-9348 .- 1608-3199. ; 66:13, s. 1298-1306
-
Journal article (peer-reviewed)abstract
- Amphibian skin secretion represents a cerain scientific interest as a source of biologically active natural peptides. In the present research skin peptidome of wide-spread European frog Rana lessonae (Camerano, 1882) was studied for the first time ever. Peptide sequencing was accomplished with Fourier transform ion cyclotron resonance mass spectrometer in collision-induced and electron capture dissociation modes. A portion of amphibian peptides contains intramolecular C-terminal disulfide cycle which obstructs mass spectrometric sequencing. Two methods were utilized to overcome this difficulty: reduction with dithiotreithol followed by thiol group alkylation and oxidation into sulfonic acid groups with performic acid. Integrated approach employed in the present study allowed the identification of 49 peptides (of 6 to 37 amino acid residues), including 19 novel species.
|
|
| 8. |
- Samgina, T. Yu., et al.
(author)
-
Mass spectral study of the skin peptide of brown frog Rana temporaria from Zvenigorod population
- 2011
-
In: Journal of Analytical Chemistry. - 1061-9348 .- 1608-3199. ; 66:14, s. 1353-1360
-
Journal article (peer-reviewed)abstract
- Skin secretions of amphibian are an interesting source of biologically active peptides. The present study provides the profile of the skin secretions of the brown frog Rana temporaria from Zvenigorod population (Russia). Sequencing of the skin secretion components has been carried out on an ion cyclotron resonance instrument with electrospray ionization and two methods of fragmentation activation, collisional activation and electron capture. For sequencing of the peptides containing intermolecular C-terminal disulfide cycle two methods of disulfide bond opening have been used: reduction with subsequent alkylation of the free thiol groups and oxidation with performic acid with the formation of sulfo-acid groups. The peptide profile of Rana temporaria studied by a complex mass spectral method has been compared with the data for the frogs of other European populations of this species. For the first time we have revealed ornithokinin-antagonist of the ornithokinin receptor-in skin secretions of amphibians.
|
|
| 9. |
- Treshchev, S.Y., et al.
(author)
-
Determination of osmium by laser-induced fluorescence in a graphite furnace in combination with an intensified charge coupled device
- 1999
-
In: Journal of Analytical Chemistry. - : Pleiades Publishing. - 1061-9348 .- 1608-3199. ; 54:3, s. 279-282
-
Journal article (peer-reviewed)abstract
- Laser-induced fluorescence in a graphite furnace with an intensified diode array is used for determining ultratrace osmium. Fluorescence spectra of osmium were investigated in a wide spectral range for five excitation transitions from the ground state. The optimum wavelengths of excitation and fluorescence were selected; the limit of detection of osmium in aqueous solutions is 50 pg.
|
|
| 10. |
- Yaropolov, A I, et al.
(author)
-
An amperometric biosensor based on laccase immobilized in polymer matrices for determining phenolic compounds
- 2005
-
In: Journal of Analytical Chemistry. - : Springer Science and Business Media LLC. - 1608-3199 .- 1061-9348. ; 60:6, s. 553-557
-
Journal article (peer-reviewed)abstract
- An amperometric enzyme electrode based on laccase for determining phenolic compounds is proposed. The following three types of polymer materials were used for enzyme immobilization on the surface of a glassy-carbon electrode: positively charged cetyl ethyl poly (ethyleneimine) (CEPEI) and negatively charged commercial Nafion and Eastman AQ 29D polymers. The advantages and disadvantages of each of the above polymers for enzyme immobilization are discussed. The detection limits of the model phenolic compounds hydroquinone and pyrocatechol in a buffer solution on laccase immobilization in a Nation membrane were 3.5 x 10(-8) and 5.0 x 10(-8) M, respectively, at a signal-to-noise ratio of 3. Electrodes with laccase immobilized in Nation and Eastman AQ 29D membranes exhibited the shortest response time. The operating stability and the stability in storage can be significantly improved by the additional incorporation of gelatin in the polymer matrices. Gelatin prevents enzyme inactivation as a result of enzyme modification by the free-radical oxidation products of phenolic compounds.
|
|
