Resolution of Polynuclear Aromatic Hydrocarbons by Packed Column GLC

Abstract

Specific GLC stationary phases have been identified which allow the resolution of certain polynuclear aromatic hydrocarbon (PAH) isomers with packed six foot columns. Phenanthrene and benz(a)anthracene can be measured in the PAH fraction of tobacco smoke condensate without significant interferences from anthracene and chrysene, respectively.     

Tobacco smoke chemistry 3. Aromatic acids of cigarette smoke condensate

A fraction containing mainly aromatic acids has been isolated from cigarette smoke condensate. Gas chromatographic and mass spectral analysis of the corresponding methyl esters and comparison with reference compounds, many of which were synthesized for this purpose, made possible the identification of 27 constituents (Table 1). Eighteen of these have not been detected in tobacco smoke condensate before.     

Tobacco smoke chemistry. 2. Alkyl and alkenyl substituted guaiacols found in cigarette smoke condensate

A series of alkyl and alkenyl substituted guaiacols, which comprise a group of biologically and organoleptically active compounds, have been synthesized. Mass spectra and GC retention times for these have been recorded and compared with those obtained for constituents of a weakly acidic fraction of smoke condensate derived from American blend type cigarettes. On the basis of these results, 25 guaiacols have been identified, 18 of which have not been detected in tobacco smoke condensate previously.     

High-pressure liquid chromatography of polynuclear aromatic hydrocarbons of cigarette smoke condensate

Reverse-phase, high-pressure liquid chromatography (h.p.l.c.) on Permaphase ODS and ETH was applied to the fractions of cigarette smoke condensate containing polynuclear aromatic hydrocarbons (PAH). A PAH-enriched fraction was first separated by gel filtration, and selected fractions were subjected to h.p.l.c. Although standard PAH could be easily separated on Permaphase ODS, results with smoke condensate were unsatisfactory. Better results were obtained with Permaphase ETH, which gave sufficient resolution for identification. PAH identification was aided by means of a stop-flow technique and measurement of the u.v. spectra of eluting peaks. Benzo(a)pyrene in the smoke condensate could be determined. However, for resolution of the PAH in smoke condensates, the total overall performance of h.p.l.c. was judged inferior to that of gas chromatography.     

Fractionation of cigarette smoke condensate for chemical and biological testing

Large-scale fractionation of cigarette smoke condensate (CSC) was carried out by gel filtration and silicic acid column chromatography, and selected fractions and their subfractions were tested for tumorigenicity by mouse-skin bioassay. The weak-acid fraction was separated into four subfractions, the polynuclear aromatic hydrocarbon (PAH) fraction into two subfractions, and the polar neutral lipid fraction into three subfractions. Also, combinations of subfractions were examined for synergic effects and portions of all active material were subjected to chemical analyses by gel filtration, column, thinlayer and gas chromatography, and ultraviolet and mass spectrometry. A weak-acid subfraction (F-63) in which catechol was concentrated, and which comprized 3.27% CSC was shown to be tumorigenic, as were combinations of this sub fraction with the active PAH (F-67) sub fraction and a polar, neutral lipid (F-70) sub fraction, representing 0.01 and 0.05% CSC, respectively. The results indicated that catechol may be a potent cocarcinogen and that the PAH in CSC interact with other components to exert a tumorigenic effect.     

Quantification of 16 polycyclic aromatic hydrocarbons in cigarette smoke condensate using stable isotope dilution liquid chromatography with atmospheric‐pressure photoionization tandem mass spectrometry

A stable isotope dilution liquid chromatography tandem mass spectrometry method for the analysis of 16 polycyclic aromatic hydrocarbons in cigarette smoke condensate was developed and validated. Compared with previously reported methods, this method has lower limits of detection (0.04–1.35 ng/cig). Additionally, the proposed method saves time, reduces the number of separation steps, and reduces the quantity of solvent needed. The new method was applied to evaluate polycyclic aromatic hydrocarbon content in 213 commercially available cigarettes in China, under the International Standardization Organization smoking regime and the Health Canadian intense smoking regime. The results showed that the total polycyclic aromatic hydrocarbon content was more than two times higher in samples from the Health Canadian intense smoking regime than in samples from the International Standardization Organization smoking regime (1189.23 versus 2859.50 ng/cig, p < 0.05). Meanwhile, the concentration of individual polycyclic aromatic hydrocarbons (and total polycyclic aromatic hydrocarbons) increased with labeled tar content in both of the tested smoking regimes. There was a positive correlation between total polycyclic aromatic hydrocarbons under the International Standardization Organization smoking regime with that under the Health Canadian intense smoking regime. The proposed liquid chromatography tandem mass spectrometry method is satisfactory for the rapid, sensitive, and accurate quantitative evaluation of polycyclic aromatic hydrocarbon content in cigarette smoke condensate, and it can be applied to assess potential health risks from smoking.     

Evanescent fluorobiosensor for the detection of polyaromatic hydrocarbon based on DNA intercalation

A flow-injection analysis (FIA) system coupled with an evanescent wave (EW) Biosensor employing total internal reflection of fluorescence radiation (TIRF) for the detection of polyaromatic hydrocarbon that intercalates into DNA is reported. A highly fluorescent intercalator, “ethidium bromide,” has been used as the reference compound for detection. The EW Biosensor was developed according to the procedure described earlier (1,2). Data on the analysis of Naphthalene, 3-methy cholanthrene, 7,12-dimethylbenz(a)anthracene, 1,2-benzanthracene, and some standard reference materials supplied by the National Institute of Standards and Technology are reported. The relative ability of the polyaromatic hydrocarbon to displace ethidium bromide, based on the relative binding ratio, is found to be on the order of 7,12-dimethylbenz[a]anthracene > 3-methylcholanthrene > 1,2-benzanthracene > napthalene.     

Gel permeation chromatography of oxygenated components of cigarette smoke condensate

Oxygenated neutral constituents of a tumor-inhibiting fraction of cigarette smoke condensate were separated from interfering phenolic compounds by a combination of silicic acid and gel chromatography. Silicic acid adsorption and Bio-Beads gel chromatography separated aliphatic from aromatic ketones, and gel chromatography on Sephadex LH-20 resolved aromatic ketones from phenols. Identifications were achieved by studying individual fractions by g.c. and g.c.—m.s.     

Determination of nitrated-polyaromatic hydrocarbons (nitro-PAHs) in environmental samples by high resolution chromatographic techniques

An analytical procedure is described for the fractionation of organic compounds present in environmental samples and the determination of nitro polyaromatic hydrocarbons (nitro-PAHs). Both low and high resolution liquid chromatography are employed for the prefractionation of the soluble organic fraction (SOF) extracted from particulate matter or gaseous pollutants collected on adsorption traps. High resolution gas chromatography is used to analyze four fractions containing alkanes, PAHs, nitro-PAHs, and other polar PAHs. Nitrogen-containing species are separated by GC and detected specifically using an alkali flame (NPD) detector. Flame ionization (FID) detection, GC-MS of positive ions, and negative ion chemical ionization MS of the whole fraction is used for the identification and quantitation of the various components. The composition of SOF extracted from particulate matter emitted from diesel exhausts is elucidated and a large number of nitro-PAHs identified by the combination of the various techniques.     

Quantitative Bestimmung von Benzo(a)pyren in Zigarettenrauchkondensaten durch Hochdruckflüssigkeits-Chromatographie (HPLC)

Following a clean-up procedure by liquid-liquid distribution and column chromatography on a layer-column silica gel/aluminium oxide, a benzo(a)pyrene concentrate from cigarette smoke condensate was separated by high pressure liquid chromatography. As selective separating system served a column with cross-linked cellulose acetate. Benzo(a)pyrene was quantitatively determined with a fluorescence detector at a detection limit of 10–30 ng/5 μl injection volume. A determination was carried out from the same benzo(a)pyrene concentrate on a reverse-phase system.     

Determination of Cd levels in smoke condensate of Brazilian and Paraguayan cigarettes by Thermospray Flame Furnace Atomic Absorption Spectrometry (TS-FF-AAS)

In this study, the concentrations of Cd in smoke condensate of Paraguayan and Brazilian full flavor normal size cigarettes were determined. A “fishtail” chimney was used to confine and direct cigarette smoke to an impaction trap followed by 3 MCE (mixed cellulose ester) filters for smoke collection. The smoke condensate collected at the first two collection stages (chimney and impactor) was prepared as Triton X-100 slurry samples and the 3 MCE filters (third collection stage) used to collect smoke were microwave digested. Samples were analyzed by Thermospray Flame Furnace Atomic Absorption Spectrometry (TS-FF-AAS) for Cd and the results obtained were compared with Graphite Furnace Atomic Absorption Spectrometry (GFAAS). No significant differences were found between the values obtained with TS-FF-AAS and GFAAS at a 95% confidence level. The total concentration of Cd in the smoke of Brazilian and Paraguayan cigarettes tested ranged from 187 to 281 ng/cigarette and from 176 to 271 ng/cigarette, respectively. The LODs for Cd using TS-FF-AAS and GFAAS, were 5.8 and 1.5 ng/cigarette, respectively, for the analysis of smoke condensate from 1 cigarette. The main advantages of using the simple TS-FF-AAS system are its low running costs and the analysis time when compared to GFAAS.     

A Highly Warped Heptagon‐Containing sp2 Carbon Scaffold via Vinylnaphthyl π‐Extension

A new strategy is demonstrated for the synthesis of warped, negatively curved, all‐sp²‐carbon π‐scaffolds. Multifold C?C coupling reactions are used to transform a polyaromatic borinic acid into a saddle‐shaped polyaromatic hydrocarbon ( 2 ) bearing two heptagonal rings. Notably, this Schwarzite substructure is synthesized in only two steps from an unfunctionalized alkene. A highly warped structure of 2 was revealed by X‐ray crystallographic studies and pronounced flexibility of this π‐scaffold was ascertained by experimental and computational studies. Compound 2 exhibits excellent solubility, visible range absorption and fluorescence, and readily undergoes two reversible one‐electron oxidations at mild potentials.     

Analytical study of cigarette smoke enriched in benzo[a]pyrene for use in model animal studies

Cigarette smoke has been significantly enriched in benzo[a]pyrene (BAP) by injecting 200 μl of a cyclohexane solution, containing a total of 40 μg of BAP, into a cigarette. After injection, the cigarette is conditioned and smoked according to standard protocol. When the cigarette smoke condensate is analyzed by fluorescence spectroscopy, liquid scintillation counting, gas chromatography with flame ionization detection, and gas chromatography-mass spectrometry, it is found that the level of BAP has increased by 1000 times with respect to levels reported for unenriched cigarette smoke. No chemical transformation of the BAP has been detected, and the BAP-enriched fraction does not appear to be perturbed to a detectable degree. Approximately 28% of the BAP is measured in the mainstream smoke, 46–48% in the sidestream smoke from the burning end of the cigarette, and 7% in the butt and ash. Correcting for analytical losses, about 10% appears to escape in the gaseous state. This material may prove suitable for model animal studies.     

Solution processable indoloquinoxaline derivatives containing bulky polyaromatic hydrocarbons: synthesis, optical spectra, and electroluminescence

New hybrid materials featuring the dipolar fragment 6H-indolo[2,3-b]quinoxaline attached to the bulkier polyaromatic hydrocarbons such as fluoranthene, triphenylene, or polyphenylated benzene have been synthesized by a two-step procedure involving Sonogashira and Diels-Alder reactions. They were characterized by absorption, emission, electrochemical, thermal, and theoretical investigations. The electronic properties of the compounds were dominated by the 6H-indolo[2,3-b]quinoxaline chromophore, and the incorporation of polyaromatic hydrocarbons reduces the chances of nonradiative deactivation processes associated with the excited state and improves the emission properties. The compounds displayed cyan emission with moderate quantum efficiency when excited at the absorption maximum. All of the compounds exhibited an irreversible reduction process corresponding to the addition of electron at the quinoxaline segment. They showed moderate thermal stability and glass transition temperature greater than 100 °C. The presence of rigid 6H-indolo[2,3-b]quinoxaline and bulkier polyaromatic hydrocarbon segments enhances the thermal stability and glass transition temperature significantly. Finally, the dyes were successfully applied as an electron-transporting and emitting layer in multilayered organic light-emitting diodes comprising a N,N'-bis(l-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine hole-transporting layer. The cyan emitting devices were characterized by moderate device performance parameters.     

A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacum L.). I. Volatile to medium-volatile constituents (b.p. ≦ 84°/0.001 Torr

The fraction b.p. ≦ 84° (0.001 Torr) from Burley tobacco condensate was carefully investigated using fractional distillation and preparative column and gas liquid chromatography aided by GLC/MS coupling. Among the 193 compounds thus separated and characterized by their spectral data, 81 were newly identified tobacco constituents. Most of the compounds isolated in the course of this work display flavouring properties which make them highly suitable for improving the flavour and aroma of tobacco and tobacco smoke.     

Determination of individual sulfur-containing compounds in gas condensate and petrol by gas chromatography

A procedure is developed for the determination of more than 60 individual sulfur-containing compounds (SCC) in liquid hydrocarbon raw materials and in liquid fuels using gas chromatography on a 25-m WCOT column, inner diameter 0.32 mm, with a nonpolar dimethylpolysiloxane stationary phase (layer thickness 5 μm) and chemiluminescence detection. SCC were identified by individual standard substances and published data. Quantitative determination was carried out by the internal standard method. The results of determination of individual SCC in petrol and stable gas condensate are presented. The most high-boiling SCC found in significant amounts (more than 0.005 wt % of sulfur) were C₂-benzothiophenes (in petrol) and C₄-dibenzothiophenes (in gas condensate).     

Characterization of cigarette smoke condensates by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOFMS). Part 2: basic fraction

Cigarette smoke condensate is a complex chemical matrix. Analysis of nitrogen-containing compounds present therein is very difficult because of the limitation of the peak capacity of conventional one-dimensional chromatography. Extensive and laborious sample preparation is frequently required or selective detectors are frequently used. In this study, the basic fraction of mainstream cigarette smoke condensate has been investigated by using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOFMS). Auto data processing by TOFMS software combined with manual identification was used to assign the components. 377 nitrogen-containing compounds, including 155 pyridine derivatives, 104 quinoline/isoquinoine derivatives, and 56 pyrazine derivatives were tentatively identified. By selecting appropriate unique masses and in the light of the component positions in the structured chromatogram, alkyl-substituted pyridines, pyrazines, and quinolines/isoquinolines were separately shown and further validated. The peaks of eight individual positional isomers of two-carbon-substituted pyridines and thirteen positional isomers of methyl-substituted quinolines/isoquinolines were further confirmed, based on linear incremental retention behavior in combination with TOFMS and the structured chromatogram of GC x GC.     

Direct and automatic capillary GC analysis for molecular weight determination and distribution in crude oils and condensates up to C20

A direct and automatic method has been developed for molecular weight (MW) determination and distribution in crude oils and condensates up to C₂₀ (340°C) by gas chromatography. Chromatographic separation has been achieved with a 50 m OV-1 fused silica capillary column, fitted with a pre-column to eliminate the fraction boiling above 340°C. The internal standard is added for quantification. Approximately 550 peaks have been identified by the use of GC/MS on different paraffinic, naphthenic, and aromatic crude oils or condensate samples. From identification and by correlation with MS group-type analysis, a carbon number and a hydrocarbon group are attributed to each peak or group of peaks. Further molecular weights have been calculated from these groups. A comparison between results from this GC method and cryometry of narrow and wide fractions shows good agreement, within the precision of cryometry. An automatic identification by computer using programmed temperature indices was used for the direct determination of molecular weight. The final report gives weight percentage, molar percentage, and molecular weight for every boiling range group and hydrocarbon group.