The use of chemometric methods of data analysis for the identification and typification of petroleum and petroleum products
T15N3
T.A. Bolotnik, Yu.V. Timchenko, I.V. Plyushchenko, V.V. Levkina,
A.V. Pirogov, A.D. Smolenkov, M.V. Popik, O.A. Shpigun
A method for identifying straits of rocket kerosene (RG-1 and T-1 brands) and various types of hydrocarbon fuels in the soil (aviation fuel ТС-1 and diesel fuel) has been developed. The proposed variant of identification is based on the preliminary separation of the main components by gas chromatography and their mass spectrometric detection, and processing of the obtained data with chemometric methods of analysis (principal component analysis and projection on latent structures with discriminant analysis) using the programs «MZmine2», «iMet-Q» and «MetaboAnalyst». The opportunity of application of the developed approach for the typification of saturated fractions of oils from different origins is illustrated.
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.
Use of molecular weight and elemental composition as an additional constraint in library search
T15N2
A.S. Samokhin, K.M. Sotnezova, I.A. Revelsky
Identification of organic compounds based only on searching against electron ionization mass spectral libraries is tentative. To increase the reliability of the identification, additional information should be used. Gas chromatographic retention indices are most often used together with mass spectra. Molecular weight and elemental composition is less frequently used, because additional experiments are required to determine these characteristics. In the present paper, we examined the influence of the molecular weight, elements present in a molecule and molecular formula on the results of the library search. It is shown that, determination of the nominal mass or molecular formula slightly increases efficiency of the library search (for example, probability that the correct compound occupies the first position in the list of possible candidates increases by only 2.8 and 3.0% respectively). On the other hand, use of additional constraints in the library search can significantly reduce the number of possible candidates and simplify predicting the absence of compound in the database.
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.
The «low-molecular» approach to identification of microorganisms by MALDI mass spectrometry
T13N3
B.L. Milman, Yu.Yu. Ilyasov, N.V. Lugovkina, A.A. Golovina1, A.V. Dmitriev
The new approach to microorganism identification is presented which includes the transformation of their MALDI mass spectra directed to decreasing mass scale by the order of magnitude and the use of the standard software for building mass spectral libraries of low-molecular compounds and library searches. The library of 728 transformed mass spectra of 182 strains for some Streptococcus species was built. With this library, the rate of true identification was estimated by cross-comparison between library mass spectra. The true identification rate is 84 % for three Streptococcus species that corresponds to the average trueness of species identification by MALDI as found in the literature. The proposed approach to identification can be considered as the method of choice for solving problems of bacteria identification.
New possibilities of dimethylformamide dimethylacetal as derivatization agent for gas chromatography/mas spectrometry analysis
T13N1
I.G. Zenkevich, T.I. Pushkareva
Надежность идентификации модельных трипептидов с использованием электрораспылительной и тандемной масс-спектрометрии
Sorry, this entry is only available in Русский.
Использование индексов удерживания для хроматомасс-спектрометрической идентификации галогенсодержащих органических соединений
Sorry, this entry is only available in Русский.
Масс-спектрометрическая идентификация высокотоксичных алкилфторфосфонатов
Sorry, this entry is only available in Русский.
Хроматомасс‑спектрометрическая идентификация примесей в изотопно‑обогащенном силане
Sorry, this entry is only available in Русский.
