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A method for the determination of nitro polycyclic aromatic compounds in particulate extracts was developed and applied to the analysis of a diesel exhaust extract. Silicic acid column chromatography combined with reduction of the nitro compounds with KBH/sub 4/ catalyzed with copper(II) chloride and derivatization with pentafluoropropionic anhydride yielded an enriched nitro fraction. Nitro polycyclic aromatic compounds present in this fraction as pentafluoropropyl amides were subsequently analyzed by capillary gas chromatography with electron capture, nitrogen-selective thermionic, and flame ionization detection and by gas chromatography/mass spectrometry. Ten nitro polycyclic aromatic compound isomers were positively identified based on comparisons of gas chromatographic retention data of standard compounds, gas chromatography/mass spectrometry, and low-resolution mass spectral data. Over 120 nitro polycyclic aromatic compounds were tentatively identified. 16 references, 4 figures, 2 tables.

Description des parametres importants dans le choix du solvant revetant et de la temperature de revetement. Influence du solvant sur les viscosites et tensions de surface

Analyse d'un liquide derive du charbon, concernant les composes aromatiques polycycliques contenant des heteroatomes azote et soufre. Les methodes d'analyse sont la chromatographie en phase gazeuse a colonne capillaire avec une detection photometrique a flamme et la spectrometrie de masse

New p-cyanophenylethylpolysiloxane and p-cyanophenylpolysiloxane stationary phases exhibiting high efficiency, cross-Iinkability, and thermal stability up to 300°C are reported in this paper. These stationary phases possess a unique blend of polar and polarizable character that has resulted in excellent selectivities for compounds having delocalized nelectrons. Another advantage of the p-cyanophenyl phases is their demonstrated relatively low elution temperatures for polar materials compared with the typical cyanopropyl polysiloxane phases.

The synthesis of phenanthro[4,5-bcd]thiophene and the four monomethylphenanthro[4,5-bcd]thiophenes is described.

A dual-flame photometric detector was modified to be used in a capillary supercritical fluid chromatographic system. The detection limit was found to be 25 ng for the sulfur mode and 0.5 ng for the phosphorus mode when supercritical carbon dioxide was used as the mobile phase. The advantages and limitations are discussed and demonstrated with several applications. 18 references, 6 figures.

Instrumentation was assembled that allows the use of supercritical ammonia as mobile phase in capillary supercritical fluid chromatography. Several modifications of the typical chromatographic system were necessary, especially with respect to injection and detection. In addition, the stabilities of various polysiloxane stationary phases were studied. The chromatography of polarizable and polar basic materials was demonstrated using a nonpolar polysiloxane stationary phase.

A fractionation method for isolating the polycyclic aromatic sulphur heterocycles from complex mixtures of polycyclic aromatic compounds was evaluated with respect to recovery for selected standard compounds. It was found that recovery varied from 0 to 70% depending on the structure of the compound. Although quantitative recovery for all components was not obtained, isolation of the sulphur heterocycle fractions has allowed the identification of many new sulphur compounds previously not identified in coal liquids and shale oils. Capillary column gas chromatography with flame photometric detection and mass spectrometry were used for the identification of individual sulphur heterocycles.

Small diameter (25–100 μm I.D. fused-silica capillary columns with non-extractable SE-33, SE-54 and 50% phenyl polysiloxane stationary phases were prepared. Elevated coating temperatures and mixed solvent coating solutions facilitated the static coating of these small-diameter columns. Azo-tert.-butane was used as the free-radical initiator for crosslinking. Stationary phase film thicknesses of up to 1 μm were successfully immobilized. Coating efficiencies were above 70% (SE-33), 50–80% (SE-54), and 20–40% (50% phenyl polysiloxane). Nearly 700,000 theoretical plates (gas chromatography) were generated by a 46 m × 50 μm I.D. column coated with a 0.25-μm film of SE-54. In general, supercritical fluid chromatography efficiencies at practical mobile phase velocities were approximately one-fifth of those produced by gas chromatography at optimum mobile phase velocities from the same columns. Experimental determinations of column performance agreed well with theoretical predictions.

A supercritical fluid chromatographic method to determine the percentage of saturates, olefins, and aromatics in gasolines and middle distillate fuels was developed. A microbore (1 mm i.d.) silica gel column was used to isolate and determine the aromatics, while a silver-ion-loaded strong cation exchange silica gel microbore column was used to separate the saturates from the olefins and aromatics. Olefins were determined by difference or by using a column switching technique which allows complete separation of saturates, olefins, and aromatics in a single run. A mixed mobile phase of 10% CO/sub 2/ in SF/sub 6/ (mole percent) was used for both columns, and a flame ionization detector provided uniform, linear response of the hydrocarbons, allowing quantitation with minimal calibration. The average absolute error was 1.5%, while the standard deviation of the area percent of the aromatics of one gasoline sample was 0.5%. Analysis times of under 60 min were achieved.

Current advances in the technology of capillary columns for gas chromatography permit extension of the range of polycyclic aromatic compounds which may be eluted. High-performance liquid chromatography (h.p.l.c.) in the non-aqueous, reversed-phase mode shows promise for separation of even larger molecules: an inquiry into the feasibility of capillary h.p.l.c. in this area has resulted in elution of polycyclic compounds containing up to eleven aromatic rings.

The stable isomers of 3- and 4-ring polycyclic aromatic sulfur heterocycles were tested for mutagenicity in the Ames standard plate incorporation test and a liquid pre-incubation modification of the Ames test. Of the 4 three-ring compounds tested, only naphtho[1,2-b]thiophene was mutagenic. Of the four-ring compounds, 7 of 13 were mutagenic in the standard Ames or pre-incubation Ames test. The highest activity for the 4-ring compounds was observed for phenanthrol[3,4-b]thiophene, a compound of approximately the same mutagenic potency in the Ames test as benzo[a]pyrene. The other active 4-ring compounds were of considerable less mutagenic potency than phenanthrol[3,4-b]thiophene. Mutagenicity for two of the 4-ring aromatic thiophenes could only be detected in the liquid pre-incubation Ames test. Salmonella typhimurium TA100 was the most sensitive strain to mutagenesis by these compounds, followed by TA98. All mutagenesis was indirect, requiring metabolic activation.

The syntheses of naphtho[1,2–6:7,6-b′]bisbenzo[b]thiophene (4), naphtho[1,2–6:7,8-b′]bisbenzo[b]thiophene (5), naphtho[2,1-b:7,6-b′]bisbenzo[b]thiophene (8), naphtho[2,1-b:7,8-b′]bisbenzo[b]thiophene (9), naphtho-[1,2–6:5,6-b′]bisbenzo[b]thiophene (14), naphtho[1,2–6:6,5-b]bisbenzo[b]thiophene (17) and naphtho[2,1–6:-6,5-b′]bisbenzo[b]thiophene (23) are reported.

Selectivite et stabilite des phases selon leur composition (teneur en siloxane) et leur structure

A separation method is described for the identification of organic compounds in synthetic fuel products. Prefractionation of crude synfuel materials into discrete chemical classes was prformed by adsorption column chromatography using small quantities of neutral aluminum oxide and silicic acid. Subsequent high-resolution separation of individual components was achieved by using capillary column gas chromatography, and specific compound types were determined by gas chromatographic retention data and combined gas chromatography-mass spectrometry. The principal chemical classes investigated in a solvent-refined coal liquid were aliphatic hydrocarbons, polycyclic aromatic hydrocarbons, polycyclic aromatic sulfur heterocycles nitrogen polycyclic aromatic compounds, and hydroxyl polycyclic aromatic hydrocarbons. The nitrogen-containing aromatic compounds were further separated into secondary nitrogen polycyclic aromatic heterocycles, amino polycyclic aromatic hydrocarbons, and tertiary nitrogen polycyclic aromatic heterocycles to facilitate their identification.

The synthesis of naphtho[1′,2′:4,5]thieno[2,3-c]quinoline (11) and four monomethyl isomers is described.

The majority of studies on non-extractable stationary phases have been done using the methylsilicones. However, there is a need for non-extractable phases containing different functional groups, such as phenyl and cyanopropyl. Tolyl groups have been incorporated into these stationary phases to facilitate free-radical cross-linking. However, it was found that tolyl and cyanopropyl groups can be oxidized during curing with peroxides, producing stationary phase films that are active and thermally unstable. If, on the other hand, azo compounds are used as the free radical generators, these problems are avoided.

A two-step pyridine and then tetrahydrofuran solvent extraction procedure at room temperature under nitrogen gas flow was used to extract two different U.S. coals, PSOC-592 (Illinois No. 5) and PSOC-521 (Rock Springs No. 7, Wyoming). Aliphatic and aromatic hydrocarbons were separated using neutral alumina column chromatography. The aromatics were then fractionated according to the number of aromatic carbons by high performance liquid chromatography (h.p.l.c.). These neutral compounds were identified by gas chromatography (g.c.) and gas chromatography/mass spectrometry (g.c./m.s.). n -Alkanes (C 17 C 31 ), pristane, phytane, hopanes (17αH, 21βH), and moretanes (17βH, 21αH) were found in aliphatic fractions of both coal extracts. Low-molecular-weight (2–4 rings) polycyclic aromatic hydrocarbons (PAH) were the major compounds in the aromatic fraction of the PSOC-592 coal extract. However, pentacyclic triterpenoid-like hydroaromatic hydrocarbons were the major components in the extract of the PSOC-521 coal. A number of new compounds were identified for the first time. Complementary structural information was obtained from 1 H and 13 C n.m.r. analysis of the isolated fractions.

Syntheses of benzo[3,4]phenanthro[1,2-b]thiophene, benzo[3,4]phenanthro[2,1-b]thiophene and their 1-methyl analogs are reported as potential constituents of solvent refined coal liquids and for mutagenicity testing. The attempted synthesis of the 13-methyl analogs which gave the 11-methyl isomers is also described. Total assignments of the 1H- and 13C-nmr spectra based on long range optimized heteronuclear protoncarbon two-dimensional chemical shift correlation are reported. Carbon assignments obtained for benzo[3,4]-phenanthro[1,2-b]thiophene using this approach were confirmed with a 125 MHz 13C–13C INADEQUATE spectrum. X-Ray crystal structures were determined for benzo[3,4]phenanthro[1,2-b]thiophene and 1-methyl-benzo[3,4]phenanthro[2,1-b]thiophene. Both molecules were helically distorted from planarity. Close intramolecular contacts between the bay region H1–H13 and ClMe-H13 of 2.03 and 2.28 A, respectively, were responsible for the distortions. There were no close intermolecular contacts of

Evaluation des avantages et des inconvenients de l'utilisation d'un plasma helium comme detecteur selectif en chromatographie SFC capillaire. Description des spectres de background pour CO 2 et NO 2 et demonstration de la detection selective de S et Cl pour plusieurs pesticides

High-molecular-weight (> 300 daltons) polycyclic aromatic compounds which were extracted from a carbon black were separated by reversed-phase high-performance liquid chromatography using gradient elution. Fractions were collected and analyzed by mass spectrometry and spectrofluorimetry. While only 15 compounds could be positively identified, 38 others were given tentative structural assignments, among which were several large sulfur heterocycles.

Theoretical considerations of column pressure drop, column diameter, pressure programming, injector and detector volumes, connector tubing, stationary phase film thickness and detector time constant as applied to open tubular supercritical fluid chromatography are treated. These theoretical considerations show that open tubular supercritical fluid chromatography is a viable technique offering its greatest potential in the pressure—temperature region around the critical point of the mobile phase.

Small diameter fused silica capillary columns (50–75 μm i.d.) were deactivated at relatively low temperatures (250–300°C) with a mixture of polymethylhydrosiloxanes and several lowmolecular-weight organosilicon hydrides. Reproducible surface deactivations of highest quality were achieved with the polymethylhydrosiloxane (PMHS) reagent. Deactivations performed with PMHS via dynamic coating with neat or diluted reagent were evaluated by gas chromatography. Deactivations achieved with organosiloxane mono-, tri-, and tetrahydrides were also evaluated and compared. Low-molecular-weight organosilicon hydride deactivations were less time consuming and required lower head pressures for filling and coating columns with the reagent. Critical surface tensions of capillary surfaces modified with PMHS and the low-molecular-weight organosilicon hydrides gave support to the dehydrocondensation reaction between silica surface silanols and silyhydride bonds of the reagents. Slopes from Zisman plots indicated that coverage of the surface ranged from highest for the polymer (PMHS) to lowest for the monomers (TMS and PMDS). Efficiency measurements showed the influence that surface modification had on the uniformity and stability of the coated capillary columns. Well-deactivated capillary columns permitted the chromatography of polar solutes using supercritical carbon dioxide as mobile phase.

Polar normal-phase HPLC fractions of a heavy-duty diesel exhaust particulate, a National Bureau of Standards standard reference material 1650, were analyzed by capillary column GC coupled to both low- and high-resolution mass spectrometry (HRMS) using electron impact and negative ion chemical ionization (NICI). Over 80 polycyclic aromatic compounds (PAC), belonging to many different chemical classes (anhydrides, carbox-aldehydes, diazaarenes, cyclic imides, nitrohydroxy-PAC, nitroaza-PAC, nitrodiaza-PAC, nitrolactones, and quinones) were tentatively identified. Ten of them were positively identified by comparison of retention times with authentic standards. Among them, phenazine and phthalic anhydride were positively identified for the first time in diesel exhaust particulates. In addition, cyclic imides and their alkylated derivatives were tentatively identified for the first time. Other novel polar chemical classes of PAC were evidenced by NICI MS using a direct-insertion probe.

The methodologies are described for isolating clean fractions of polycyclic aromatic compounds from diverse environmental samples such as air particulate matter, sediments, and fish tissue. The common step in all procedures is the separation of the polycyclic aromatic compound fraction into well-defined chemical classes by adsorption chromatography on an alumina column. These procedures greatly facilitate the detailed characterization of the polycyclic aromatic hydrocarbons, sulfur heterocycles, and nitrogen heterocycles by capillary column gas chromatography.

In supercritical fluid chromatography (SFC) the mobile phase is neither a gas nor a liquid, but is a supercritical fluid. As a result of the unique properties of supercritical fluids, SFC is rapidly becoming a prominent separation technique for the analysis of reactive, thermally labile, and nonvolatile compounds. This article reviews the history, instrumentation, and practice of the technique. Particular emphasis is placed on the different programming methods that allow elution to be selectively controlled in ways that are unique to SFC.

Sensitivity, selectivity, linear range, long-term stability and operating conditions of a new nitrogen-sensitive thermionic detector were investigated. The detector was combined with high-efficiency glass open tubular columns in order to detect trace nitrogen-containing constituents in the complex mixtures of volatiles from human urine and tobacco aroma A complex nitrogen profile was also obtained from a nitromethane extract of airborne particulate matter.

The coupling of a capillary supercritical fluid chromatograph with a high resolution double focusing mass spectrometer has been accomplished without any modifications to the pumping or ion source systems. The interface utilizes a direct insertion probe (DIP), which was originally designed for the direct analysis of solid samples, together with a trit restrictor as a decompression device. The DIP is placed opposite to the SFC restrictor, and it provides sufficient heat to prevent cluster formation and cooling resulting from the expansion of the supercritical fluid into the vacuum environment. Excellent mass spectra of standard polycyclic aromatic hydrocarbons under chemical-ionization (CI) conditions using methane as the reagent gas, and under charge-exchange (CE) conditions using CO2 as the charge exchange medium were obtained.

In cases where high efficiency is required to resolve complex mixtures of either thermally labile or nonvolatile organic compounds, capillary supercritical fluid chromatography may be the most desirable analytical method. While great strides in this new technology have been made over the last few years, several problem areas are requiring increased attention. These include sample introduction systems, pressure reduction at the end of the column, column stability in various supercritical mobile phases, and migration of polar solute molecules. This paper describes the state-of-the-art in capillary SFC with emphasis on the progress made and future needs in the solutions to these specific problems.

L'utilisation d'une phase cristalline liquide de siloxane polymere comme phase stationnaire dans une colonne de chromatographie fluide supercritique permet d'accroitre la selectivite de l'analyse vis-a-vis des isomeres des composes aromatiques polycycliques contenus dans les produits petroliers

1-Methylphenanthro[3,4-b]thiophene was prepared by the photocyclization of 1-(4′-methyl-2′-thienyl)-2-(2″-naphthyl)ethene. The 1H and 13C-nmr spectra were assigned using two-dimensional 1H/13C heteronuclear chemical shift correlation and relayed coherence transfer (RELAY) experiments. From nuclear Overhauser difference spectra, the H11-C1 methyl-H intramolecular distance was determined to be 2.10 A. The molecule crystallized from chloroform in the monoclinic system, space group P21/c. A total of 3536 unique reflections were measured and the structure was solved by direct methods and refined to a final R = 0.049. The molecule is helical with both chiral forms observed in the crystal. The H11-C1 methyl-H distance in the crystal was 2.12(3)A in excellent agreement with the distance measured in solution by NOE techniques.

A crosslinkable biphenylmethylpolysiloxane stationary phase was synthesized for capillary column gas chromatography and compared with methyl, phenyl, and cyanopropyl polysiloxane stationary phases for the separation of isomeric polycyclic aromatic compounds. While the new phase gave similar separations of nonpolar isomers when compared to the nonpolar phases, separations of polar isomers were greatly improved because of the induced polarity of the biphenyl group of the stationary phase by the solute molecules. This polarizable stationary phase offers a unique selectivity which is not available in other stationary phases.

Several selective polysiloxane stationary phases were evaluated for the resolution of nitrogen-containing polycyclic aromatic compounds (N-PAC) in coal tar fractions by capillary column gas chromatography. A new liquid crystalline polysiloxane exhibited the highest selectivity for isomeric alkylated 3- and 4-ring N-PAC, whereas a polarizable biphenyl polysiloxane and a moderately polar crown ether-substituted polysiloxane were more applicable for the analysis of 2- and 3-ring N-PAC. The thermal stabilities of these phases made them suitable for GC-MS applications.

A new interface for capillary column supercritical fluid chromatographymass spectrometry (SFC-MS) is described and initial results are presented. The advantages of SFC include the ability to separate high molecular weight, nonvolatile, and thermally unstable compounds not amenable to GC. A capillary column SFC-MS interface can replace HPLC-MS in most applications and has advantages due to the higher possible chromatographic efficiency, mobile phase volatility, and the simplicity of the interface design. Pressure programming during the chromatographic separation also allows precise control over the solvating power of the supercritical fluid mobile phase. The direct fluid injection interface provides for transfer of the total SFC effluent into a chemical ionization source. Results are presented to illustrate the separation analysis of mixtures of aromatic hydrocarbons and styrene oligomers using n -pentane and carbon dioxide as the mobile phase.

Bullhead catfish, Ictalurus nebulosus, and rainbow trout, Salmo gairdneri, were subjected to two coal-derived substances to evaluate each material for potential carcinogenic activity. Substances tested included a solvent-refined coal heavy distillate and a sediment extract from an industrially polluted river in Ohio. Two subfractions, one containing the polycyclic aromatic hydrocarbons and the other containing the nitrogen heterocycles of each material were also tested. Following a 16-h exposure period, the gill and liver tissues were removed and examined by standard light and electron microscopy techniques. Hyperplasia of the gill tissue and some engorgement with blood of the secondary lamellae were observed with the light microscope. At the electron microscope level, hepatocyte mitochondria were swollen with a loss of cristae, and rough endoplasmic reticulum fragmented. Results suggest that most of the treatments studied induced pathological responses in fish. Of the two fish tested, the rainbow trout was the most sensitive indicator of environmental pollution.

Empirical quantitative models have been studied that relate the phosphorescence transition energies of thiophene benzologs and corresponding aromatic hydrocarbon systems. Phosphorescence 0,0 bands, phosphorescence/fluorescence quantum yield ratios, and phosphorescence lifetimes of 12 thiophene benzologs of which the phosphorescence properties were unknown are reported.

All isomers of the monomethylbenzo[b]naphth[2,1-d]thiophenes were synthesized using photocyclization of 3-styrylbenzo[b]thiophenes. The 1-, 3-, 4-, and 5-methylbenzo[b]naphtho[2,1-d]thiophenes were synthesized by irradiation of the corresponding methylated 3-styrylbenzo[b]thiophenes which were prepared by the Wadsworth-Emmons reaction of diethyl benzo[b]thenylphosphonate with o-, m-, p-tolualdehyde and acetophenone. The 7-, 8-, 9- and 10-methylbenzo[b]naphtho[2,1-d]thiophenes were synthesized by decarboxylation of 7-, 8-, 9- and 10-methylbenzo[b]naphtho[2,1-d]thiophene-6-carboxylic acid with copper in quinoline. These carboxylic acids were prepared by photocyclization of the corresponding 2-(benzo[b]thiophen-3-yl)-3-phenylpropenoic acids which were prepared by the condensation of the methylated benzo[b]thiophene-3-ylacetic acids with benzaldehyde in the presence of triethylamine in acetic anhydride.

A method is described for the complete separation of the amino polycyclic aromatic hydrocarbons (amino-PAH) from complex coal-derived mixtures. After pre-fractionation, the use of derivatisation with pentafluoropropionic anhydride of the amino-PAH-rich isolate of an SRC-II heavy distillate coal liquid enabled the complete separation of this chemical class to be achieved by gel permeation chromatography. The fluoroamide derivatives were converted back to the original amino functionality by catalytic hydrolysis on neutral aluminium oxide. Subsequent high-resolution separation of individual components was obtained by capillary column gas chromatography, and specific compounds were determined by gas chromatographic retention data and gas chromatography/mass spectrometry.

Complex mistures of nitrogen-containing polyaromatics (aza-arenes) require fractionation for improved resolution and trace component enrichment prior to gas chromatographic—mass spectrometric (GC—MS) identification. Suitably of high-performance liquid chromatography using a polar stationary phase to meet this goal is demonstrated. Evaluation of stationary phases for the separation of complex aza-arene mixtures by capillary GC was carried out using selectivity, thermal stability, and column deactivation as criteria. Separation up to 5-ring structures aresubsequently demonstrated, using the basic fraction of cannabis smoke condensate and coal tar as example.

A series of alkenyl-substituted cholesterol and related steroids have been prepared. These liquid-crystalline compounds were hydrosilylated onto polyhydromethylsiloxane. The polymers have a broad range of liquid crystallinity even if the starting alkenes had a narrow range. Those polymers containing the benzoate ester linking group were not suitable for stationary phases in high temperature capillary gas chromatography because the phases were not stable at temperatures above 250°C-27O°C. A capillary column coated with a polymer containing a phenyl group directly attached to the steroid proved to be effective in separating certain PAH isomers.

In order to prevent plugging during deactivation of small diameter (50 μm i.d.) capillary columns for gas and supercritical fluid chromatography, various high temperature deactivation methods were employed. Pure hexamethyldisilazane and hexamethyldisiloxane (a substitute for D4) were dynamically coated on the column, while a film (0.05 μm) of OV-101 was statically coated, before high temperature (450°C) treatment. Excellent deactivated columns were obtained, and no significant difference in column activity was observed using any of these three methods.

Ten new liquid-crystalline alkene compounds based on the biphenylcarboxylate ester have been prepared. Some of these alkenes, along with liquid-crystalline alkenes previously reported, were attached to polysiloxane polymers and tested as stationary phases in capillary column gas chromatography. The phase containing nearly 50% substitution with the biphenylcarboxylate ester side groups which were each separated from the polysiloxane backbone by a three-carbon and an ether- oxygen spacer proved to have the best chromatographic properties.