Fixed-charge generation derivatization for analysis of thiols by «soft» ionization mass spectrometry methods
T16N1
A.V. Kozlov, R.S. Borisov, V.G. Zaikin
A new method for the fixed-charge generation derivatization of thiols of different structures by reaction with haloalkanes and dibromides was suggested. It was shown that 1,4-dibromobutane and 1,2-xylylene dibromide are the most effective alkylating agents, that provided the formation of stable five-membered ring with a positively charged sulfur atom. Such cations are readily detected by electrospray ionization and matrix-assisted laser desorption/ionization mass spectrometry methods. Sulfonium cations were further studied by tandem mass spectrometry using collision-induced dissociation (CID). Typical and specific directions of CID for cyclic cations formed from thiols of different structures were established. They can be used to identify and quantify the thiol analytes by the selected reaction monitoring method.
Studying of handwritten strokes aging kinetics by high-performance liquid chromatography/mass spectrometry
T15N4
D.I. Baygildieva, , T.M. Baygildiev, О.A. Shpigun, I.A. Rodin
One of the central problems of documents forensic examination is the determination of the ink deposition date by such common writing instruments as ballpoint pens. To solve this problem, it is necessary to get information about the composition of ballpoint pen inks that were used for depositing inks, to get information about qualitative and quantitative changes of components undergoing in time after depositing inks on a document, as well as to know changes in the composition and properties of the ink caused by environmental influences or intentional effects on document such as photo-, thermal-, UV-, IR-radiations, microwave and other types of external influences.
Therefore, the purpose of this research was to develop an approach that allows one to detect changes and establish dependence of these changes in the ballpoint pen composition that occur in strokes over time. As a result of this study, the possibilities of liquid chromatography/mass spectrometry for the detection of changes over time in the composition of ballpoint pen inks BIC Original, Corvina 51 and Pilot were estimated. Modeling of the dyes degradation under the influence of UV radiation on strokes was carried out. Kinetic parameters that describe the degree of dyes conversion were determined.
On the tryptic peptide features providing their detection and identification by MALDI mass spectrometry
T15N3
B.L. Milman1, А.V. Solov’eva, N.V. Lugovkina, I.K. Zhurkovich
The tryptic peptide features providing detection and identification of these bio compounds and corresponding proteins by matrix-assisted laser desorption/ionization mass spectrometry (MALDI) with the α-cyano-4-hydroxycinnamic acid matrix, are determined and discussed. Twenty five proteins were identified; the features of reliably identified peptides are compared to those of peptides which might be produced by tryptic cleavage and were not detected. Two key factors enhancing a detection possibility of tryptic peptides, were determined. The first one refers to the gas-phase peptide basicity, which is the highest for the C-terminal end arginine peptides; this reason for the emergence of big analytical signals is well-known. The second factor providing ionization of peptides under consideration in the MALDI conditions is their hydrophility. This result does not correlate with the most conclusions of earlier relevant researches and discussed in the article.
H3O+(H2O)n reagent ion. Calculation of the structure, thermodynamic parameters of hydration, equilibrium composition and mobility
T15N3
A.V. Lebedev
H3O+(H2O)n reagent ion is widely used in ion mobility spectrometry and atmospheric pressure chemical ionization mass spectrometry. In this work, the calculated data on the structure and properties of the H3O+(H2O)n (n = 0–4) reagent ion are obtained that are of interest for the study of the chemical ionization regularities, prediction and interpretation of ion mobility spectra and mass spectra. Using quantum chemical methods we computed the structure and refined isomeric composition of the H3O+(H2O)n ions. It is found that ions with n = 2, 3 and 4 have 2, 5 and 15 isomers respectively. The most stable isomers, which had a branched non-cyclic structure with the H3O+ core, are determined. The thermodynamic parameters of hydration reactions of the most stable isomers of H3O+(H2O)n (n = 0–3) and the equilibrium composition of the reagent ion in a wide range of temperatures and concentrations of water vapor are computed. The obtained results are consistent with the existing experimental and calculated data. Using the computed structural data and data on the composition of the reagent ion, its mobility is calculated by the trajectory method. The calculation error close to the experimental one is reached.
Determination of total saturated and total aromatics in oils and oil products by mass spectrometry and gas chromatography/mass spectrometry with electron ionization
T15N2
E.S. Brodsky, A.A. Shelepchikov, G.A. Kalinkevich, E.Ya Mir-Kadyrova
A method of total saturated and total aromatics determination in oils and oil products by electron ionization mass spectra is presented. The contribution of saturated and aromatic hydrocarbons to the total ion current is found by solving a system of linear equations with coefficients that take stock a mutual interference of mass spectra of saturated and aromatic hydrocarbons.
Resonant electron attachment to glucose and fructose molecules
T15N1
P.V. Shchukin, M.V. Muftakhov
Low-energy negative ion mass spectra of glucose and fructose suggest deep fragmentation of short-lived molecular ions. Analysis of metastable ions in the mass spectra shows that some decomposition reactions proceed through intermediate ions [M–H2O]– •, etc. Along with the general similarity of ionization processes in the isomers, there is a significant difference in the intensive formation of ions at m/z 71 from glucose.
Review. Mass Spectrometry of physiologically active substances prohibited in Sports: The problem of screening a wide range of compounds and their metabolites
T14N3
E.D. Virus, A.V. Ivanov, D.P. Luzyanin, A.A. Kubatiev
For the last 35 years, chromatography/mass spectrometry has been the main method of screening of physiologically active substances banned in sports. A characteristic feature of anti-doping control is the screening of a wide range of compounds with the applying of a large number of analytical procedures. This article introduces the reader to various approaches to the determination of physiologically active substances banned by World Anti-Doping Agency (WADA) using mass spectrometry. The article describes various aspects of the anti-doping control and the criteria under which substances are caught in the WADA list. A detailed description of the pharmacological properties of certain classes of prohibited substances in the article should help to purposefully identify the potential “candidates” for WADA list. Considering the intensity of replenishment of the WADA list with “new” classes of prohibited substances and significant time and material costs associated with the implementation of a large number of analytical procedures in doping control, the need to find new approaches to screening a wide range of bioregulators in anti-doping control is emphasized.
Phospholipid composition of human blood plasma as detected by matrix-assisted laser desorption/ionization mass spectrometry: new observations
T14N2
B.L. Milman, N.V. Lugovkina, I.K. Zhurkovich
The dependence of matrix-assisted laser desorption/ionization (MALDI) mass spectra of lipids extracted from human blood plasma and corresponding lipid compositions on different experimental conditions was studied. Not only numerous compounds from groups of lysophosphatidylcholines (LPC) and phosphatidylcholines (PC) but also lipid oxidation products including six oxidized LPC, were detected. They were available in the original samples and also produced by the reaction with air oxygen molecules resulted in their accumulation in samples under analysis. A higher sensitivity of MALDI detection was observed for less hydrophobic LPC as compared to more hydrophobic PC and was explained. The hydrophobicity/lipophilicity factor was possibly revealed when the matrix of 2,5-dihydroxybenzoic acid has been replaced by α-cyano-4-hydroxycinnamic acid. The latter was rarely used in MALDI of lipids and may be suitable for the selective determination of LPC and oxidized LPC.
New approaches to the application of DART mass spectrometry coupled with planar chromatography for analysis of mixtures of organic compounds
T14N1
M.V. Ovcharov, S.S. Barsegyan, S.A. Kovaleva, L.N. Kulikova, R.S. Borisov
A desorption cell for TLC/DART mass spectrometry is developed. Analysis of mixtures of pharmaceutical substances has shown that the proposed approach can improve the sensitivity of the method and achieve the reproducibility of recorded mass spectra and selected ions chromatograms.
The comparison between «low-molecular» and conventional approaches to species identification of bacteria by MALDI mass spectrometry
T13N4
B.L. Milman, V.V. Gostev, A.V. Dmitriev
The new approach to bacteria identification which uses the standard software for building mass spectral libraries of low-molecular compounds and for corresponding library searches, is compared to the conventional approach based on the commercial Biotyper software and database. The results are obtained for the random sample of 100 mass spectra of 25 strains of S. pyogenes, S. dysgalactiae subsp. equisimilis and S. anginosus. The spectra were sampled from the database of 728 mass spectra of 182 strains for some Streptococcus species. Both approaches were proved to result in the similar identification as 80–88 % of true outcomes. For similar reference mass spectra and the same identification criteria, the identification results were very close to each other as 24 agreements for 25 strains. This is the result from that different estimations of the mass spectral similarity included in programs under the comparison lead to the correlation of similarity indicators. A difference of identification results is mainly due to not the same reference databases and also different identification criteria.
