Polycyclic aromatic hydrocarbons identified in soot extracts from domestic coal-burning stoves of Henan Province, China.

Using high-pressure liquid chromatography with ultraviolet-visible diode-array detection, we have analyzed polycyclic aromatic hydrocarbons (PAH) in the dichloromethane extracts of soot deposits from coal-burning stoves in several homes of Henan Province, China--including Linxian County, where esophageal cancer rates are some of the highest in the world. Thirty-two individual polycyclic aromatic compounds, ranging in size from three to eight fused aromatic rings, have been unequivocally identified among the soot extract components--including 20 benzenoid PAH, 6 fluoranthene benzologues, 1 cyclopentafused PAH, 1 indene benzologue, 3 oxygenated PAH, and 1 ring-sulfur-containing aromatic. Most of the identified compounds have been observed before among the products of laboratory coal pyrolysis experiments, but two of the components, the six-ring C24H14 napthol[1,2-b]fluoranthene and the eight-ring C30H16 tribenzo[e,ghi,k]perylene, have never before been documented as products of coal in any system. All of the Henan coal soot extracts are remarkably similar qualitatively in that they contain the same set of identified PAH, but absolute levels of individual species vary by up to 5 orders of magnitude, from sample to sample. The bulk of the identified component mass in all of these soot extracts lies in the five- and six-ring PAH--the largest single class being the family of five-ring C20H12 isomers, to which the samples' most abundant components, benzo[b]fluoranthene and benzo[e]pyrene, belong. The five- and six-ring PAH also account for the majority of the samples' known mutagens. The three strong mutagens identified in these soot samples are the C20H12 benzo[a]-pyrene and two C24H14 PAH, dibenzo[a,e]pyrene and naphtho-[2,1-a]pyrene. Seven moderate mutagens are found among the C20H12, C22H12, C22H14, and C24H14 PAH. A major class of mutagens, the cyclopenta-fused PAH, appears to be absent from these samples, but our detection of an oxidation product of the major mutagen cyclopenta[cd]- pyrene--itself mutagenic--suggests that these soot deposits may contain additional mutagenic cyclopentafused PAH oxidation products as well.

QSRR prediction of chromatographic retention of ethynyl-substituted PAH from semiempirically computed solute descriptors.

Retention prediction of 12 ethynyl-substituted polycyclic aromatic hydrocarbons (PAH) and their six unsubstituted parent compounds has been elucidated by the application of quantitative structure-retention relationship (QSRR) analysis. Retention data of the PAH were obtained from reversed-phase high-pressure liquid chromatography (HPLC) utilizing an octadecylsilica stationary phase operated under linear-gradient elution (60:40 water/acetonitrile to pure acetonitrile in 40 min). Six solute descriptors (moment of inertia, total energy, polarizability, ionization potential, dipole moment, subpolarity), computed from the optimized semiempirical AM1, MNDO, and PM3 solute geometries, were examined. Results from one-parameter QSRR analysis showed that retention of solutes was best predicted with solute polarizability as the parameter, computed from the AM1-(r = 0.969), MNDO-(r = 0.970), or PM3 (r = 0.967)-optimized solute geometries. From two-parameter QSRR analysis involving a size-specific parameter accompanied by a polarity parameter, it was found that solute retention was best reproduced by using solute polarizability and subpolarity as the parameters calculated from the AM1-(r = 0.983), MNDO-(r = 0.983), or PM3 (r = 0.984)-optimized solute geometries. On the basis of the results from both one-parameter and two-parameter regression analysis, the two-parameter QSRR equation with polarizability and subpolarity as parameters was found to be the best relation in relating solute molecular structure to retention under the HPLC conditions investigated. The results obtained in this study are of significance to predicting the identify of unknown product components based solely on parameters derived from solute structure.

The effect of ethynyl substitution and cyclopenta fusion on the ultraviolet absorption spectra of polycyclic aromatic hydrocarbons.

We have examined the UV spectra of six newly-synthesized ethynyl-PAH (1-ethynylnaphthalene, 5-ethynylacenaphthylene, 1-ethynylanthracene, 9-ethynylphenanthrene, 3-ethynylfluoranthene, and 1-ethynylpyrene) and five corresponding CP-PAH (acenaphthylene, aceanthrylene, acephenanthrylene, cyclopenta[cd]fluoranthene, and cyclopenta[cd]pyrene) and have found the following systematic behavior: ethynyl-substitution results in average bathochromic shifts of 5 nm for the lower-wavelength beta- and beta'-bands and of 18 nm for the higher-wavelength p-band, as well as an amplification of the p-band with respect to the beta-band; the addition of a peripheral cyclopenta ring results in average bathochromic shifts of 7 nm in the beta-band, 16 nm in the beta'-band, and 44 nm in the p-band, compared to the wavelengths in the corresponding unsubstituted PAH. The addition of a cyclopenta ring also decreases the resolution of vibrational fine structure in the cases where the fine structure is particularly intense in the spectrum of the unsubstituted PAH. The effects of ethynyl substitution on the UV spectra of PAH are sufficiently consistent that new ethynyl-PAH should be identifiable based on their UV spectra alone.

The relationship between mutagenicity and chemical composition of polycyclic aromatic compounds from coal pyrolysis.

The polycyclic aromatic compounds (PAC) produced from the pyrolysis of a bituminous coal at temperatures of 1125 to 1425 degrees K prove to be mutagenic to S. typhimurium, both in the presence and in the absence of postmitochondrial supernatant (PMS) prepared from Aroclor 1254-induced rat liver. Mutagenicity of the PAC samples measured in the absence of PMS exhibits little dependence on pyrolysis temperature; that measured in its presence is higher at the higher pyrolysis temperatures. However, because of the decrease in PAC yield as the temperature is raised, mutagenicity per mass of coal consumed falls with an increase in temperature if measured without PMS (-PMS) and peaks at an intermediate temperature of 1378 degrees K if measured with PMS (+PMS). Using a new chromatographic technique, we have split each coal-derived PAC sample into two fractions: LC1, containing PAC with alkyl and O-containing substitutions and LC2, consisting of unsubstituted PAC. Substituted (LC1) fractions show no significant +PMS mutagenicity, indicating that, as a whole, the alkylated PAC in our coal pyrolysis products are not mutagenic. Only at the higher temperatures do the substituted fractions exhibit significant -PMS mutagenicity, attributed to PAC with carbonyl or etheric functionalities. The extremely low yields of the substituted PAC under the conditions where they show some activity, however, ensure that they contribute little to overall mutagenicity. In contrast to the substituted fractions, the unsubstituted (LC2) fractions display significant mutagenicity under all conditions and appear to be responsible for virtually all of the mutagenicity in these coal-derived PAC samples. In this fraction, -PMS activity is attributed to nitrogen-containing heterocyclic aromatics.

Evaluation of cyano bonded phases for the fractionation of bioactive complex mixtures.

Cyanopropyl bonded-phase sorbents are investigated for the liquid chromatographic (LC) fractionation of complex mixtures with the goal of extending routine sample fractionation to samples containing highly polar biologically active components. Separations based both on gravity-flow column chromatography and on high performance liquid chromatography (HPLC) are evaluated for efficiency and resolving power. Typical gravity-flow column separations of neutral to moderately polar mixtures are found to be less effective than those employing traditional sorbents; however, HPLC methods could be called upon to provide the resolving power necessary for satisfactory separations of these mixtures. For mixtures of polar reference compounds, cyano bonded phases provide good separations and are very efficient, permitting the elution of components too polar to be recovered from traditional sorbents. A scheme combining gravity-flow chromatography with HPLC is developed for the fractionation of complex mixtures into compound classes. It is based on the chromatographic behavior of reference compounds covering a wide polarity range utilizing cyanopropyl sorbents exclusively. Results are presented for the fractionation of two air particulate reference samples containing highly polar components.

Organic emissions from coal pyrolysis: mutagenic effects.

Four different types of coal have been pyrolyzed in a laminar flow, drop tube furnace in order to establish a relationship between polycyclic aromatic compound (PAC) evolution and mutagenicity. Temperatures of 900K to 1700K and particle residence times up to 0.3 sec were chosen to best simulate conditions of rapid rate pyrolysis in pulverized (44-53 microns) coal combustion. The specific mutagenic activity (i.e., the activity per unit sample weight) of extracts from particulates and volatiles captured on XAD-2 resin varied with coal type according to the order: subbituminous greater than high volatile bituminous greater than lignite greater than anthracite. Total mutagenic activity (the activity per gram of coal pyrolyzed), however, varied with coal type according to the order: high volatile bituminous much greater than subbituminous = lignite much greater than anthracite, due primarily to high organic yield during high volatile bituminous coal pyrolysis. Specific mutagenic activity peaked in a temperature range of 1300K to 1500K and generally appeared at higher temperatures and longer residence times than peak PAC production.