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.     

Two new alkaloids from cigarette smoke condensate

Chemical constituents of MeOH extracts of cigarette smoke were studied. Two new alkaloids, named cigatin A (1), 2-(Pyridine-3-yloxy)-benzene-1',4'-diol and B (2), 2-(4-Methyl-pyridin-3-yloxy)-benzene-1',4'-diol, were isolated from a mainstream condensate of cigarette together with seven known alkaloids. Their structures were determined on the basis of spectral data and chemical methods.     

Simultaneous determination of amino-alpha-carbolines and amino-gamma-carbolines in cigarette smoke condensate by high-performance liquid chromatography

A method for the simultaneous detection of amino-alpha-carbolines (2-amino-alpha-carboline and 2-amino-3-methyl-alpha-carboline) and amino-gamma-carbolines (3-amino-1,4-dimethyl-5H-pyrido [4,3-b]indole and 3-amino-1-methyl-5H-pyrido [4,3-b]indole) by high-performance liquid chromatography has been developed. It consists of a three-step purification using three different columns with fluorometric detection. With this method, we have demonstrated that both amino-alpha-carbolines and amino-gamma-carbolines are present in cigarette smoke condensate. The method may be useful for detecting these carcinogens in various materials.     

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.     

Gel permeation chromatography of fullerene-centered macromolecules

Gel permeation chromatography (GPC) behavior of fullerene-centered macromolecules is investigated. Because of the globular shape of the macromolecules, their GPC results are different from those of linear polystyrene standards. These macromolecules may serve as alternative molecular weight standards for polymers or dendrimers of similar globular structures. The results also show that the GPC analysis is capable of discerning relatively minor structural differences in the fullerene-centered macromolecules.     

Gel permeation chromatography of branched polyethylene

The effect of long-chain branching must be considered in gel permeation chromatography to evaluate the molecular weight polydispersity of branched polyethylenes. Osmotic molecular weights of fractions of branched polyethylene were correlated with elution volumes; weight-average and number-average molecular weights of a branched polyethylene were determined. Molecular weight changes on crosslinking polyethylene by ionizing radiation are accompanied by branching and cannot be simply interpreted by gel permeation chromatography.     

Gel permeation chromatography of polyamide by N-trifluoroacetylation

Successful chromatograms were obtained for trifluoroacetylated nylon 12 (N-TFA-N) in gel permeation chromatography (GPC) with dichloromethane as eluent. It was confirmed that the method of universal calibration was applicable for N-TFA-N and polystyrene. The average molecular weights of nylon 12 were obtained from the chromatogram of N-TFA-N by use of the calibration curve for polystyrene. The stability of N-TFA-N in solution was examined from various angles. Satisfactory results are obtained, if the sample solution is measured within 48 h after preparation.     

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.     

Gel permeation chromatography: Effect of pore-size distribution

The pore-size distributions of various grades of porous glass were determined by gas desorption and mercury porosimeter measurements. This allowed the calculation of elution volumes as a function of pore diameters. The coil sizes of polystyrenes in toluene were obtained for a series of molecular weights from hydrodynamic theory and matched with pore diameters. In this manner, expected calibration curves for gel permeation chromatography could be calculated. Good agreement was found with experimental data.     

Gel permeation chromatography: Examination of column efficiency

Gel permeation chromatographic (GPC) separations have been performed with several commercially available column packing materials. The results have been analyzed in the conventional manner to obtain the ratio of weight average to number-average molecular weight, M_w/M_n, for solutes with narrow molecular weight distribution. Various other parameters proposed to measure the efficiency of GPC columns have been evaluated and compared. It is proposed that the experimentally determined value of M_w/M_n for a series of different molecular weight samples with similar, narrow distribution for a given set of columns is a convenient parameter for comparing column efficiency in GPC. This parameter may be calculated from a single chromatogram unlike resolution, R, resolution index, RI, or specific resolution, RS, which require a pair of chromatograms. Results from the M_w/M_n method are usually in agreement with those from the R, RI, and RS calculations but one exception has been found. The number of theoretical plates calculated from the elution of a small molecule or from the polymer peak bears little relation to efficiencies predicted from the proposed M_w/M_n method or from R, RI, or RS.     

Determination of benzo[a]pyrene in cigarette smoke condensate by liquid chromatography on amberlite xad-2

A method is described for the determination of benzo[a]pyrene in cigarette smoke condensate which utilizes chromatographic fractionation on Amberlite XAD-2. PAH are initially separated by step-wise gradient elution, progressing from reverse to normal-phase modes of operation. Other separation steps involve automated column chromatography on silica gel and thin-layer chromatography on 20% acetylated cellulose. Benzo[a]pyrene is finally determined by u.v. spectrophotometry and liquid scintillation counting of ¹⁴C—benzo[a]pyrene tracer. Results obtained compare favorably with those of the more traditional liquid—liquid extraction methods.     

Gel permeation chromatography on polyelectrolytes in aqueous solution

Gel permeation chromatography of water-soluble polymers, with special attention to polyelectrolytes, has been studied. A three-detector system (refractometry, conductimetry, viscometry) is used to characterize the polymers. A single curve is obtained for the calibration of the set of columns taking into account the hydrodynamic volume of the solutes and using a 0.1 N salt solution as the eluent to screen electrostatic forces. The role of the low adsorption of dextran on silica gel is pointed out. The dependence of elution volume on polymer concentration is demonstrated and interpreted in terms of the screening length of the molecules.     

Gel permeation chromatography of simple anions in aqueous solutions

Semi-automatic liquid chromatographic apparatus is described for the separation of simple inorganic anions in aqueous solution, using dextran gels for the separation and differential conductivity for detection. The influence of different types of eluent on the degree and order of separation is discussed.     

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.     

Gel permeation chromatography of polyethylene: Effect of long-chain branching

The effect of long-chain branching on the size of low-density polyethylene molecules in solution is demonstrated through solution viscosity and molecular weight measurements on fractionated samples. These well-characterized fractions are analyzed by gel permeation chromatography (GPC), and it is shown that the separation of the polymer molecules by this technique is sensitive to the presence of long-chain branching. By using fractions of branched polyethylene possessing differing degrees of branching, one observes that a single curve is adequate in relating elution volume to molecular weight. This calibration curve is applied in the GPC analysis of a variety of commercial low-density polyethylene resins and it is shown, by comparison with independent osmometric and gradient elution chromatographic data, that realistic values for molecular weight and molecular weight distribution are obtained. The replacement of molecular weight M by the parameter [η]M as a function of elution volume, leads to a single relationship for both linear and branched polyethylenes. This indicates that GPC separation takes place according to the hydrodynamic volumes of the polymer molecules. The comparison of data for polyethylene and polystyrene fractions suggests that this volume dependence of the separation will be observed for other polymer–solvent systems.