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Jan T. Andersson - One of the best experts on this subject based on the ideXlab platform.
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Polycyclic aromatic Sulfur Heterocycles as source diagnostics of petroleum pollutants in the marine environment
Standard Handbook Oil Spill Environmental Forensics, 2016Co-Authors: Abdelrahman H. Hegazi, Jan T. AnderssonAbstract:Source identification of petroleum pollutants in the marine environment is a very difficult but important task for both environmentalists and governments and many markers are used to reach this goal. Among these are the polycyclic aromatic Sulfur Heterocycles (PASHs) that are presented here. This chapter discusses Sulfur compounds in crude oil and petroleum products, the changes in PASH patterns upon treatment of petroleum in refineries, the stability of these compounds in the marine environment, and the analytical methods and techniques used for petroleum PASH analysis. The chapter focuses on how PASHs can be used both as source and weathering markers in spilled petroleum pollutant source identification.
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DeSulfurized Fuels from Athabasca Bitumen and Their Polycyclic Aromatic Sulfur Heterocycles. Analysis Based on Capillary Electrophoresis Coupled with TOF MS
Energy & Fuels, 2012Co-Authors: Thies Nolte, Tjorben Nils Posch, Carolin Huhn, Jan T. AnderssonAbstract:Polycyclic Aromatic Sulfur Heterocycles (PASHs) are undesirable compounds in fuels and refined petroleum-based products. Capillary electrophoresis (CE) was investigated as an alternative to analyze the preisolated PASHs from partially deSulfurized materials derived from Athabasca, Canada, bitumen. The sample complexity is considerably reduced by this preisolation by ligand exchange chromatography on a Pd(II) containing phase and subsequent ionization of the neutral PASHs through S-methylation to impart electrophoretic mobility. The PASH components are separated and characterized using CE with a time-of-flight mass spectrometer (TOF MS) as detector. An additional major advantage of the CE separation is that the drawbacks of HPLC (limited separation efficiency) and GC (volatility limitations) for separations of high molecular weight compounds can be circumvented. CE was demonstrated to be a highly efficient method in the separation of PASHs and up to 200,000 theoretical plates were obtained. The practicabil...
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Products of polycyclic aromatic Sulfur Heterocycles in oil spill photodegradation
Environmental toxicology and chemistry, 2011Co-Authors: Eiman M. Fathalla, Jan T. AnderssonAbstract:Photo-oxidation is a potentially significant process in the degradation of crude oil spilled in the environment. The polycyclic aromatic Sulfur Heterocycles (PASHs) in an Egyptian crude oil (0.8 % Sulfur) were photo-oxidized as a film on the surface of water in the presence of anthraquinone as photosensitizer under simulated solar irradiation. The polar photoproducts were characterized using negative ion electrospray ionization with time of flight mass spectrometry and, after trimethylsilylation, gas chromatography with mass spectrometry. The photoproducts identified revealed the presence of a large variety of sulfonic acids, aliphatic and aromatic acids, and alcohols. The data also give new information on the substituents of the aromatic compounds in the unexposed oil and indicate the presence of cyclohexyl substituted aromatic compounds. Environ. Toxicol. Chem. 2011;30:2004–2012. © 2011 SETAC
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Analysis of polycyclic aromatic Sulfur Heterocycles in Egyptian petroleum condensate and volatile oils by gas chromatography with atomic emission detection
Fuel Processing Technology, 2011Co-Authors: Nagy E. Moustafa, Jan T. AnderssonAbstract:Eight Egyptian petroleum condensates and two volatile oils were analyzed by gas chromatography. The condensate oils range in color from colorless to yellow and brown. The samples are composed mainly of saturates hydrocarbons (C3 to C35). The polycyclic aromatic Sulfur Heterocycles (PASH) were isolated through use of a silica bonded palladium(II)-complex and their distribution investigated by gas chromatography (GC) with atomic emission detection (AED) in the Sulfur-selective mode. The condensate oils show distinctly different distributions of the PASHs, some containing mainly benzothiophenes, and others both benzo- and dibenzothiophenes and a third group in which the dibenzothiophenes strongly dominate. The alkyl substituted Sulfur compounds are quantified. The distribution patterns of the PASHs are correlated to the type of reservoir source rocks.
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Capillary electrophoretic separation of polycyclic aromatic Sulfur Heterocycles
Analytical and bioanalytical chemistry, 2009Co-Authors: Thies Nolte, Jan T. AnderssonAbstract:Capillary electrophoresis (CE) was used to separate polycyclic aromatic Sulfur Heterocycles (PASHs), a class of compounds that occurs in fossil fuels and refined products of petroleum. An electric charge was introduced into the compounds through methylation or phenylation of the Sulfur atom. Separations of standard PASHs that are expected to be present in industrially deSulfurized fuels showed that CE possessed a higher resolution than reversed phase liquid chromatography. The CE method can separate all the monomethylbenzothiophenes; this is not achieved in capillary gas chromatography. A linear relationship was found between migration time and the calculated volume of the compounds. The PASHs in deeply deSulfurized diesel were separated after preconcentration, and the electropherogram was compared with the chromatograms from GC and HPLC. Finally, derivatized PASHs are often enantiomeric and the enantiomers can be separated if a suitable cyclodextrin is added to the running buffer.
Zhimin Yao - One of the best experts on this subject based on the ideXlab platform.
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preparation of polydimethylsiloxane β cyclodextrin divinylbenzene coated dumbbell shaped stir bar and its application to the analysis of polycyclic aromatic hydrocarbons and polycyclic aromatic Sulfur Heterocycles compounds in lake water and soil by
Analytica Chimica Acta, 2009Co-Authors: Zhimin YaoAbstract:Abstract A “dumbbell-shaped” stir bar was proposed to prevent the friction loss of coating during the stirring process, and thus prolonged the lifetime of stir bars. The effects of the coating components, including polydimethylsiloxane (PDMS), β-cyclodextrin (β-CD) and divinylbenzene (DVB) were investigated according to an orthogonal experimental design, using three polycyclic aromatic hydrocarbons (PAHs) and four polycyclic aromatic Sulfur Heterocycles (PASHs) as model analytes. Four kinds of stir bars coated with PDMS, PDMS/β-CD, PDMS/DVB and PDMS/β-CD/DVB were prepared and their extraction efficiencies for the target compounds were compared. It was demonstrated that PDMS/β-CD/DVB-coated stir bar showed the best affinity to the studied compounds. The preparation reproducibility of PDMS/β-CD/DVB-coated stir bar ranged from 3.2% to 15.2% (n = 6) in one batch, and 5.2% to 13.4% (n = 6) among batches. The “dumbbell-shaped” stir bar could be used for about 40 times, which were 10 extractions more than a normal stir bar. The prepared PDMS/β-CD/DVB-coated “dumbbell-shaped” stir bar was used for stir bar sorptive extraction (SBSE) of PAHs and PASHs and the desorbed solution was introduced into HPLC-UV for subsequent analysis. The limits of detection of the proposed method for seven target analytes ranged from 0.007 to 0.103 μg L−1, the relative standard deviations were in the range of 6.3–12.9% (n = 6, c = 40 μg L−1), and the enrichment factors were 19–86. The proposed method was successfully applied to the analysis of seven target analytes in lake water and soil samples.
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Preparation of polydimethylsiloxane/beta-cyclodextrin/divinylbenzene coated "dumbbell-shaped" stir bar and its application to the analysis of polycyclic aromatic hydrocarbons and polycyclic aromatic Sulfur Heterocycles compounds in lake water and soi
Analytica chimica acta, 2009Co-Authors: Zhimin YaoAbstract:A "dumbbell-shaped" stir bar was proposed to prevent the friction loss of coating during the stirring process, and thus prolonged the lifetime of stir bars. The effects of the coating components, including polydimethylsiloxane (PDMS), beta-cyclodextrin (beta-CD) and divinylbenzene (DVB) were investigated according to an orthogonal experimental design, using three polycyclic aromatic hydrocarbons (PAHs) and four polycyclic aromatic Sulfur Heterocycles (PASHs) as model analytes. Four kinds of stir bars coated with PDMS, PDMS/beta-CD, PDMS/DVB and PDMS/beta-CD/DVB were prepared and their extraction efficiencies for the target compounds were compared. It was demonstrated that PDMS/beta-CD/DVB-coated stir bar showed the best affinity to the studied compounds. The preparation reproducibility of PDMS/beta-CD/DVB-coated stir bar ranged from 3.2% to 15.2% (n = 6) in one batch, and 5.2% to 13.4% (n = 6) among batches. The "dumbbell-shaped" stir bar could be used for about 40 times, which were 10 extractions more than a normal stir bar. The prepared PDMS/beta-CD/DVB-coated "dumbbell-shaped" stir bar was used for stir bar sorptive extraction (SBSE) of PAHs and PASHs and the desorbed solution was introduced into HPLC-UV for subsequent analysis. The limits of detection of the proposed method for seven target analytes ranged from 0.007 to 0.103 microg L(-1), the relative standard deviations were in the range of 6.3-12.9% (n = 6, c = 40 microg L(-1)), and the enrichment factors were 19-86. The proposed method was successfully applied to the analysis of seven target analytes in lake water and soil samples.
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Preparation of polydimethylsiloxane/β-cyclodextrin/divinylbenzene coated “dumbbell-shaped” stir bar and its application to the analysis of polycyclic aromatic hydrocarbons and polycyclic aromatic Sulfur Heterocycles compounds in lake water and soil b
Analytica Chimica Acta, 2009Co-Authors: Zhimin YaoAbstract:Abstract A “dumbbell-shaped” stir bar was proposed to prevent the friction loss of coating during the stirring process, and thus prolonged the lifetime of stir bars. The effects of the coating components, including polydimethylsiloxane (PDMS), β-cyclodextrin (β-CD) and divinylbenzene (DVB) were investigated according to an orthogonal experimental design, using three polycyclic aromatic hydrocarbons (PAHs) and four polycyclic aromatic Sulfur Heterocycles (PASHs) as model analytes. Four kinds of stir bars coated with PDMS, PDMS/β-CD, PDMS/DVB and PDMS/β-CD/DVB were prepared and their extraction efficiencies for the target compounds were compared. It was demonstrated that PDMS/β-CD/DVB-coated stir bar showed the best affinity to the studied compounds. The preparation reproducibility of PDMS/β-CD/DVB-coated stir bar ranged from 3.2% to 15.2% (n = 6) in one batch, and 5.2% to 13.4% (n = 6) among batches. The “dumbbell-shaped” stir bar could be used for about 40 times, which were 10 extractions more than a normal stir bar. The prepared PDMS/β-CD/DVB-coated “dumbbell-shaped” stir bar was used for stir bar sorptive extraction (SBSE) of PAHs and PASHs and the desorbed solution was introduced into HPLC-UV for subsequent analysis. The limits of detection of the proposed method for seven target analytes ranged from 0.007 to 0.103 μg L−1, the relative standard deviations were in the range of 6.3–12.9% (n = 6, c = 40 μg L−1), and the enrichment factors were 19–86. The proposed method was successfully applied to the analysis of seven target analytes in lake water and soil samples.
Stephen A Wise - One of the best experts on this subject based on the ideXlab platform.
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Qualitative characterization of three combustion-related standard reference materials for polycyclic aromatic Sulfur Heterocycles and their alkyl-substituted derivatives via normal-phase liquid chromatography and gas chromatography/mass spectrometry.
Analytical and bioanalytical chemistry, 2018Co-Authors: Walter B. Wilson, Hugh V. Hayes, Andres D. Campiglia, Stephen A WiseAbstract:The research described here provides the most comprehensive qualitative characterization of three combustion-related standard reference materials (SRMs) for polycyclic aromatic Sulfur Heterocycles (PASHs) and some alkyl-substituted (alkyl-) derivatives to date: SRM 1597a (coal tar), SRM 1991 (coal tar/petroleum extract), and SRM 1975 (diesel particulate extract). An analytical approach based on gas chromatography/mass spectrometry (GC/MS) is presented for the determination of three-, four-, and five-ring PASH isomers and three- and four-ring alkyl-PASHs in the three SRM samples. The benefit of using a normal-phase liquid chromatography (NPLC) fractionation procedure prior to GC/MS analysis was demonstrated for multiple isomeric PASH groups. Using a semi-preparative aminopropyl (NH2) LC column, the three combustion-related samples were fractionated based on the number of aromatic carbon atoms. The NPLC-GC/MS method presented here allowed for the following identification breakdown: SRM 1597a – 35 PASHs and 59 alkyl-PASHs; SRM 1991–31 PASHs and 58 alkyl-PASHs; and SRM 1975–13 PASHs and 25 alkyl-PASHs. These identifications were based on NPLC retention data, the GC retention times of reference standards, and the predominant molecular ion peak in the mass spectrum. Prior to this study, only 11, 1, and 0 PASHs/alkyl-PASHs had been identified in SRM 1597a, SRM 1991, and SRM 1975, respectively.
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The Influence of Aromaticity in Gas Chromatography Retention: The Case of Polycyclic Aromatic Sulfur Heterocycles
Chromatographia, 2018Co-Authors: Jorge O. Oña-ruales, Walter B. Wilson, Yosadara Ruiz-morales, Fernando Alvarez-ramírez, Stephen A WiseAbstract:Aromaticity has been used as a criterion to explain the gas chromatographic (GC) retention of cata -condensed polycyclic aromatic Sulfur Heterocycles (PASHs) C_12H_8S, C_16H_10S, C_20H_12S; and peri -condensed PASHs C_18H_10S, in a GC column with 50% phenyl/50% dimethyl silphenylene polymer. To establish the aromaticity, nucleus-independent chemical shifts at the level of the molecular plane, NICS(0), and at 1 Å above the surface of the molecular plane, NICS(1), have been used. It has been found that the GC retention of cata -condensed PASHs C_12H_8S, C_16H_10S, and C_20H_12S is satisfactorily defined by the aromaticity of the entire molecule, and the GC retention of peri -condensed PASHs C_18H_10S is satisfactorily defined by the local aromaticity in the Sulfur pentagonal ring. In addition, the positive slope between GC retention and NICS(0) of the entire molecule for cata -condensed PASHs, C_12H_8S and C_16H_10S, and by NICS(1) in the pentagonal ring for peri -condensed PASHs, C_18H_10S, is explained by the interaction between the electrons of the heterocycle molecule and the positive pole of the silicon atom in the GC column, as suggested with PAHs. In contrast, the negative slope between GC retention and aromaticity for cata -condensed C_20H_12S is explained by the presence of bay , cove , or fjord regions in the vicinity of the Sulfur atom that generates either higher GC retention and lower aromaticity or lower GC retention and higher aromaticity.
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Normal-phase liquid chromatography retention behavior of polycyclic aromatic Sulfur Heterocycles and alkyl-substituted polycyclic aromatic Sulfur heterocycle isomers on an aminopropyl stationary phase
Analytical and bioanalytical chemistry, 2017Co-Authors: Walter B. Wilson, Lane C. Sander, Hugh V. Hayes, Andres D. Campiglia, Stephen A WiseAbstract:Retention indices for 67 polycyclic aromatic Sulfur Heterocycles (PASHs) and 80 alkyl-substituted PASHs were determined using normal-phase liquid chromatography (NPLC) on an aminopropyl (NH2) stationary phase. The retention behavior of PASH on the NH2 phase is correlated with the number of aromatic carbon atoms and two structural characteristics have a significant influence on their retention: non-planarity (thickness, T) and the position of the Sulfur atom in the bay-region of the structure. Correlations between solute retention on the NH2 phase and T of PASHs were investigated for three cata-condensed (cata-) PASH isomer groups: (a) 13 four-ring molecular mass (MM) 234 Da cata-PASHs, (b) 20 five-ring MM 284 Da cata-PASHs, and (c) 12 six-ring MM 334 Da cata-PASHs. Correlation coefficients ranged from r = −0.49 (MM 234 Da) to r = −0.65 (MM 334 Da), which were significantly lower than structurally similar PAH isomer groups (r = −0.70 to r = −0.99). The NPLC retention behavior of the PASHs are compared to similar results for PAHs.
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Retention behavior of isomeric polycyclic aromatic Sulfur Heterocycles in gas chromatography on stationary phases of different selectivity.
Journal of chromatography. A, 2017Co-Authors: Walter B. Wilson, Stephanie G. Mössner, Milton L. Lee, Lane C. Sander, Jorge O. Oña-ruales, Leonard M. Sidisky, Stephen A WiseAbstract:Retention indices for 48 polycyclic aromatic Sulfur Heterocycles (PASHs) were determined using gas chromatography with three different stationary phases: a 50% phenyl phase, a 50% liquid crystalline dimethylpolysiloxane (LC-DMPS) phase, and an ionic liquid (IL) phase. Correlations between the retention behavior on the three stationary phases and PASH geometry (L/B and T, i.e., length-to-breadth ratio and thickness, respectively) were investigated for the following four isomer sets: (1) 4 three-ring molecular mass (MM) 184Da PASHs, (2) 13 four-ring MM 234Da PASHs, (3) 10 five-ring MM 258Da PASHs, and (4) 20 five-ring MM 284Da PASHs. Correlation coefficients for retention on the 50% LC-DMPS vs L/B ranged from r=0.50 (MM 284Da) to r=0.77 (MM 234Da). Correlation coefficients for retention on the IL phase vs L/B ranged from r=0.31 (MM 234Da) to r=0.54 (MM 284Da). Correlation coefficients for retention on the 50% phenyl vs L/B ranged from r=0.14 (MM 258Da) to r=0.59 (MM 284Da). Several correlation trends are discussed in detail for the retention behavior of PASH on the three stationary phases.
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Retention behavior of isomeric polycyclic aromatic Sulfur Heterocycles in reversed-phase liquid chromatography
Journal of chromatography. A, 2016Co-Authors: Walter B. Wilson, Milton L. Lee, Lane C. Sander, Miren Lopez De Alda, Stephen A WiseAbstract:Retention indices for 70 polycyclic aromatic Sulfur Heterocycles (PASHs) were determined using reversed-phase liquid chromatography (LC) on a monomeric and a polymeric C18 stationary phase. Molecular shape parameters [length, breadth, thickness (T), and length-to-breadth ratio (L/B)] were calculated for all the compounds studied. Correlations between the retention on the polymeric C18 phase and PASH geometry (L/B and T) were investigated for six specific PASH isomer groups with molecular mass (MM) 184Da, 234Da, 258Da, 284Da, 334Da, and 384Da. Similar to previous studies for polycyclic aromatic hydrocarbons (PAHs), PASH elution order on the polymeric C18 phase was generally found to follow increasing L/B values. Correlation coefficients for retention vs L/B ranged from r=0.45 (MM 184Da) to r=0.89 (MM 284Da). In the case of smaller PASHs (MM≤258Da), the location of the Sulfur atom in the bay-region of the structure resulted in later than expected elution of these isomers based on L/B. In the case of the larger PASHs (MM≥284Da), nonplanarity had a significant influence on earlier than predicted elution based on L/B values.
Claudia Alcaraz Zini - One of the best experts on this subject based on the ideXlab platform.
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Silver bonded to silica gel applied to the separation of polycyclic aromatic Sulfur Heterocycles in heavy gas oil.
Journal of Chromatography A, 2016Co-Authors: Thiago Rodrigues Bjerk, Elina Bastos Caramao, Edilson Valmir Benvenutti, Marcelo Barbalho Pereira, Eliana Weber De Menezes, Claudia Alcaraz ZiniAbstract:Abstract Silica gel containing silver ions was prepared and characterized. Silica was organofunctionalized with 3-mercaptopropyl group by using grafting reaction followed by silver ions adsorption (silver covalently bonded to mercaptopropyl silca gel, Ag-MPSG). The organofunctionalization and silver coordination were observed by transmission infrared spectroscopy and elemental analyses (CHN and EDS). The textural characteristics were studied by N 2 adsorption-desorption isotherms. Additionally, optical properties were studied by diffuse reflectance spectroscopy. The Ag-MPSG material was employed as stationary phase for the first time for fractionation of a heavy gas oil sample resulting in a fraction that is richer in polycyclic aromatic Sulfur Heterocycles (PASH). The fractions were analyzed by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detector and Ag-MPSG material provided similar fractionation performance when compared to conventional material [palladium covalently bonded to mercaptopropyl silca gel, Pd(II)-MPSG] usually employed for the same purpose and as the cost of silver is less than the one of palladium, the cost of the fractionation phase was reduced.
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Palladium(II) chemically bonded to silica surface applied to the separation and identification of polycyclic aromatic Sulfur Heterocycles in heavy oil
Journal of separation science, 2013Co-Authors: Maria Elisabete Machado, Elina Bastos Caramao, Edilson Valmir Benvenutti, Eliana Weber De Menezes, Lucas Panizzi Bregles, Claudia Alcaraz ZiniAbstract:Separation of polycyclic aromatic Sulfur Heterocycles among themselves and also from interferents in petrochemical matrices is a challenging task because of their low concentration, matrix complexity, and also due to the presence of polyaromatic hydrocarbons, as they present similar physico-chemical properties. Therefore, the objective of this work was preparation, characterization, and application of a stationary phase for separation of these compounds in a heavy gas oil sample and their identification by comprehensive two-dimensional gas chromatography. The stationary phase was prepared by grafting mercaptopropyltrimethoxisilane onto a silica surface, followed by palladium(II) chloride immobilization. Elemental analysis, thermogravimetry, nitrogen adsorption-desorption isotherms, infrared analysis, and scanning electron microscopy were performed to characterize this solid phase. Sulfur compounds were separated in an open column packed with the stationary phase and analyzed by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometric detection. The number of compounds tentatively identified was 314 and their classes were thiophenes, benzotiophenes, dibenzothiophenes, naphthothiophenes, benzonaphthothiophenes, and dinaphthothiophenes. Separation among Sulfur compounds and polyaromatic hydrocarbons was successful, which is a difficult goal to achieve with the traditionally employed solid phases. Some recalcitrant compounds (dibenzothiophenes with substituents of two and four carbons) were fully separated and tentatively identified.
Walter B. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Qualitative characterization of three combustion-related standard reference materials for polycyclic aromatic Sulfur Heterocycles and their alkyl-substituted derivatives via normal-phase liquid chromatography and gas chromatography/mass spectrometry.
Analytical and bioanalytical chemistry, 2018Co-Authors: Walter B. Wilson, Hugh V. Hayes, Andres D. Campiglia, Stephen A WiseAbstract:The research described here provides the most comprehensive qualitative characterization of three combustion-related standard reference materials (SRMs) for polycyclic aromatic Sulfur Heterocycles (PASHs) and some alkyl-substituted (alkyl-) derivatives to date: SRM 1597a (coal tar), SRM 1991 (coal tar/petroleum extract), and SRM 1975 (diesel particulate extract). An analytical approach based on gas chromatography/mass spectrometry (GC/MS) is presented for the determination of three-, four-, and five-ring PASH isomers and three- and four-ring alkyl-PASHs in the three SRM samples. The benefit of using a normal-phase liquid chromatography (NPLC) fractionation procedure prior to GC/MS analysis was demonstrated for multiple isomeric PASH groups. Using a semi-preparative aminopropyl (NH2) LC column, the three combustion-related samples were fractionated based on the number of aromatic carbon atoms. The NPLC-GC/MS method presented here allowed for the following identification breakdown: SRM 1597a – 35 PASHs and 59 alkyl-PASHs; SRM 1991–31 PASHs and 58 alkyl-PASHs; and SRM 1975–13 PASHs and 25 alkyl-PASHs. These identifications were based on NPLC retention data, the GC retention times of reference standards, and the predominant molecular ion peak in the mass spectrum. Prior to this study, only 11, 1, and 0 PASHs/alkyl-PASHs had been identified in SRM 1597a, SRM 1991, and SRM 1975, respectively.
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The Influence of Aromaticity in Gas Chromatography Retention: The Case of Polycyclic Aromatic Sulfur Heterocycles
Chromatographia, 2018Co-Authors: Jorge O. Oña-ruales, Walter B. Wilson, Yosadara Ruiz-morales, Fernando Alvarez-ramírez, Stephen A WiseAbstract:Aromaticity has been used as a criterion to explain the gas chromatographic (GC) retention of cata -condensed polycyclic aromatic Sulfur Heterocycles (PASHs) C_12H_8S, C_16H_10S, C_20H_12S; and peri -condensed PASHs C_18H_10S, in a GC column with 50% phenyl/50% dimethyl silphenylene polymer. To establish the aromaticity, nucleus-independent chemical shifts at the level of the molecular plane, NICS(0), and at 1 Å above the surface of the molecular plane, NICS(1), have been used. It has been found that the GC retention of cata -condensed PASHs C_12H_8S, C_16H_10S, and C_20H_12S is satisfactorily defined by the aromaticity of the entire molecule, and the GC retention of peri -condensed PASHs C_18H_10S is satisfactorily defined by the local aromaticity in the Sulfur pentagonal ring. In addition, the positive slope between GC retention and NICS(0) of the entire molecule for cata -condensed PASHs, C_12H_8S and C_16H_10S, and by NICS(1) in the pentagonal ring for peri -condensed PASHs, C_18H_10S, is explained by the interaction between the electrons of the heterocycle molecule and the positive pole of the silicon atom in the GC column, as suggested with PAHs. In contrast, the negative slope between GC retention and aromaticity for cata -condensed C_20H_12S is explained by the presence of bay , cove , or fjord regions in the vicinity of the Sulfur atom that generates either higher GC retention and lower aromaticity or lower GC retention and higher aromaticity.
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Normal-phase liquid chromatography retention behavior of polycyclic aromatic Sulfur Heterocycles and alkyl-substituted polycyclic aromatic Sulfur heterocycle isomers on an aminopropyl stationary phase
Analytical and bioanalytical chemistry, 2017Co-Authors: Walter B. Wilson, Lane C. Sander, Hugh V. Hayes, Andres D. Campiglia, Stephen A WiseAbstract:Retention indices for 67 polycyclic aromatic Sulfur Heterocycles (PASHs) and 80 alkyl-substituted PASHs were determined using normal-phase liquid chromatography (NPLC) on an aminopropyl (NH2) stationary phase. The retention behavior of PASH on the NH2 phase is correlated with the number of aromatic carbon atoms and two structural characteristics have a significant influence on their retention: non-planarity (thickness, T) and the position of the Sulfur atom in the bay-region of the structure. Correlations between solute retention on the NH2 phase and T of PASHs were investigated for three cata-condensed (cata-) PASH isomer groups: (a) 13 four-ring molecular mass (MM) 234 Da cata-PASHs, (b) 20 five-ring MM 284 Da cata-PASHs, and (c) 12 six-ring MM 334 Da cata-PASHs. Correlation coefficients ranged from r = −0.49 (MM 234 Da) to r = −0.65 (MM 334 Da), which were significantly lower than structurally similar PAH isomer groups (r = −0.70 to r = −0.99). The NPLC retention behavior of the PASHs are compared to similar results for PAHs.
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Retention behavior of isomeric polycyclic aromatic Sulfur Heterocycles in gas chromatography on stationary phases of different selectivity.
Journal of chromatography. A, 2017Co-Authors: Walter B. Wilson, Stephanie G. Mössner, Milton L. Lee, Lane C. Sander, Jorge O. Oña-ruales, Leonard M. Sidisky, Stephen A WiseAbstract:Retention indices for 48 polycyclic aromatic Sulfur Heterocycles (PASHs) were determined using gas chromatography with three different stationary phases: a 50% phenyl phase, a 50% liquid crystalline dimethylpolysiloxane (LC-DMPS) phase, and an ionic liquid (IL) phase. Correlations between the retention behavior on the three stationary phases and PASH geometry (L/B and T, i.e., length-to-breadth ratio and thickness, respectively) were investigated for the following four isomer sets: (1) 4 three-ring molecular mass (MM) 184Da PASHs, (2) 13 four-ring MM 234Da PASHs, (3) 10 five-ring MM 258Da PASHs, and (4) 20 five-ring MM 284Da PASHs. Correlation coefficients for retention on the 50% LC-DMPS vs L/B ranged from r=0.50 (MM 284Da) to r=0.77 (MM 234Da). Correlation coefficients for retention on the IL phase vs L/B ranged from r=0.31 (MM 234Da) to r=0.54 (MM 284Da). Correlation coefficients for retention on the 50% phenyl vs L/B ranged from r=0.14 (MM 258Da) to r=0.59 (MM 284Da). Several correlation trends are discussed in detail for the retention behavior of PASH on the three stationary phases.
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Retention behavior of isomeric polycyclic aromatic Sulfur Heterocycles in reversed-phase liquid chromatography
Journal of chromatography. A, 2016Co-Authors: Walter B. Wilson, Milton L. Lee, Lane C. Sander, Miren Lopez De Alda, Stephen A WiseAbstract:Retention indices for 70 polycyclic aromatic Sulfur Heterocycles (PASHs) were determined using reversed-phase liquid chromatography (LC) on a monomeric and a polymeric C18 stationary phase. Molecular shape parameters [length, breadth, thickness (T), and length-to-breadth ratio (L/B)] were calculated for all the compounds studied. Correlations between the retention on the polymeric C18 phase and PASH geometry (L/B and T) were investigated for six specific PASH isomer groups with molecular mass (MM) 184Da, 234Da, 258Da, 284Da, 334Da, and 384Da. Similar to previous studies for polycyclic aromatic hydrocarbons (PAHs), PASH elution order on the polymeric C18 phase was generally found to follow increasing L/B values. Correlation coefficients for retention vs L/B ranged from r=0.45 (MM 184Da) to r=0.89 (MM 284Da). In the case of smaller PASHs (MM≤258Da), the location of the Sulfur atom in the bay-region of the structure resulted in later than expected elution of these isomers based on L/B. In the case of the larger PASHs (MM≥284Da), nonplanarity had a significant influence on earlier than predicted elution based on L/B values.
