Application of lanthanum stearate monolayers as a metal-affinity sorbent for the selective sorption of soman adducts to human serum albumin.

A new metal-affinity sorbent based on lanthanum stearate monolayers has been developed and characterized. The prospect of its application to specific extraction of organophosphorous compound (OP) adducts of blood proteins was demonstrated. For this, the patterns of soman adducts of human serum albumin (HSA) were comprehensively characterized by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS).

Regression algorithm for calculating second-dimension retention indices in comprehensive two-dimensional gas chromatography.

Gas chromatography-mass spectrometry (GC-MS) is one of the most accurate, well developed, and reliable analytical tools for the analysis of volatile and semivolatile compounds. The GC-MS data have been extensively improved by enhancing the separation capacity via comprehensive two-dimensional gas chromatography (GC × GC). The reliability of the identification of the analytes in GC × GC-MS can be notably improved by applying the second-dimension retention index (2I) as additional analytical parameter along with the commonly used first dimension retention index (1I) and mass spectrum. A novel approach for calculating second-dimension retention indices (2I) for semivolatile organic compounds is proposed. It is noteworthy that the standards used in calculations are the same compounds recommended as internal standards by US EPA 8270 Method for analysis of semivolatile organic compounds. The new algorithm takes into account the analyte retention time and its retention temperature at the secondary column, (2tR) and (2TR), respectively. The experimental data collected with different primary oven temperature ramp rates and carrier gas flow rates have shown that the calculated by the proposed approach 2I values remain the same for each evaluated compound, drifting in a very narrow range. The proposed approach was tested using 100 organic compounds from various chemical classes including alkanes, phenols, nitrobenzenes, chlorinated hydrocarbons, anilines, polycyclic aromatic hydrocarbons (PAHs), phthalates, etc. The important advantage of the proposed 2I values for compounds of the same chemical origin (reference standards and analytes) involves applicability of well-known Lee's indices for non-polar phases. Therefore, the proposed approach can be used in targeted and non-targeted analysis of a wide range of organic compounds. The reduced version of the second dimension retention indices provides a valuable mapping of the homologues series of organic compounds, making their detection and identification easy and reliable.

Application of histograms in evaluation of large collections of gas chromatographic retention indices.

The effective use of gas chromatographic retention data presented in the form of retention indices (RI) requires the development of a comprehensive structure-based digital archive of retention parameters. Development of such an archive includes the collection of all available RI values for a variety of compounds including replicates measured under slightly different conditions. Review of retention data often shows a relatively wide range of RI values for certain well studied compounds that is larger than expected on the basis of the simple reproducibility of experimental measurements. The finding of unusual RI data distributions and their examination presents a possible way to detect and correct errors during the development of comprehensive RI libraries. Our approach involves the construction of histograms representing the distribution of data-points in various RI intervals. The observed shape of the distribution is compared to the expected and observed shapes for well-identified compounds. Significant systematic deviations represent anomalies in the sets of RI data. The occurrence of more than a single maximum on a histogram generally indicates the presence of erroneous data. For some compounds such multimode RI distributions may be caused by differences in experimental conditions of the RI determination. The construction and interpretation of histograms for compounds with multiple RI measurements is illustrated by several examples. Thus, the RI sub-set for the diterpene alcohol, isophytol, was separated from the RI data set for phytol and four additional sub-groups of published RI data for one of the sesquiterpenes, gamma-elemene, were re-identified as alpha-, beta-, delta-elemenes and germacrene B.

Development of a database of gas chromatographic retention properties of organic compounds.

A comprehensive database of gas chromatographic retention properties of chemical compounds has been developed using multiple literature sources. The National Institute of Standards and Technology (NIST) database of retention data for non-polar and polar stationary phases currently contains 292,924 data records for 42,888 compounds. The database includes data for Kováts indices, linear indices, Lee indices, retention times and retention volumes. The first release of this database for non-polar stationary phases is available with NIST/US Environmental Protection Agency (EPA)/National Institutes of Health (NIH) Mass Spectral Database (June 2005) and through the internet (NIST Chemistry WebBook). The paper describes the database and the process by which it has been compiled. The format of data presentation and the quality control procedures are described. Data sources of gas chromatographic retention data are also discussed.

Using new structurally related additive schemes in the precalculation of gas chromatographic retention indices of polychlorinated hydroxybiphenyls on HP-5 stationary phase.

A new additive scheme is proposed for the precalculation of gas chromatographic retention indices of complex organic compounds. The principal feature of this approach is the absence of previously calculated I increments for any structural fragments or functional groups in the molecule. Instead, arithmetical operations involving I values of simpler structural analogues of target compounds are used directly. I precalculation for polychlorinated hydroxybiphenyls (839 congeners) on the HP-5 stationary phase was chosen as one of the most important applications of the method under discussion. Such a large number of congeners cannot be obtained as reference samples and their gas chromatographic (GC)-mass spectrometric (MS) identification should therefore be based currently on precalculated I values.

Gas chromatographic analysis of essential oils with preliminary partition of components.

The efficiency of using combinations of retention indices and partition coefficients (Kp) with a hexane: acetonitrile system has been demonstrated by taking as an example the essential oil from Artemisia pallens Wall. Preliminary partition of the components between the two partly mixing liquids provides information by which components can be attributed to the appropriate homologous series. The use of group constants (j), which are functions of both partition coefficients and GC retention indices, in the practice of identifying the components of essential oils is reported for the first time.

[The forensic chemical study of psilocybine-containing fungi]. / Sudebno-khimicheskoe issledovanie psilotsibinsoderzhashchikh gribov.

A method for isolating the main components (psilocybin and psilocine) from Psilocybe semilanceata mushrooms, their identification and measurement by thin-layer and gas-liquid chromatography, chromatographic mass-spectrometry, and inverse-phase high-performance liquid chromatography is developed.

Gas chromatographic-mass spectrometric determination of volatile organic compounds in an urban atmosphere.

Polysorbimide and carbochrome, new sorbents with high temperature stability, have been used to concentrate trace amounts of atmospheric pollutants, and 136 C1-C13 organic compounds, including 126 hydrocarbons, 6 oxygen derivatives and 3 chlorides, were identified in air samples collected in the streets of Leningrad. One of the major features of the composition of the organic constituents of the urban air sampled is the presence of a number of CnH2n hydrocarbons (mainly olefins), and also CnH2n-2 and CnH2n-4 unsaturated hydrocarbons (including alpha-pinene and camphene). A comparison of the results with those of similar studies carried out on air samples from Zürich, Houston and Paris is of considerable interest in connection with the possible effect of geographical factors on the composition and lifetime of organic pollutants in the atmosphere.