(14) Atmospheric Environment Service, “Wind Summary-Trail
Tadanac”, Government of Canada, 1975,1976. (15) Parker, A., Richards, S. H., “Instruments Used for the Measurement of Atmospheric Pollution in Great Britain”, in Air Pollution-Proceedings of U.S. Tech. Conf. on Air Pollution, McGraw-Hill, New York, N.Y., 1952. (16) Hickey, H. R., Hendrickson, E. R., J . Air Pollut Control Assoc., 15 (9), 409-14 (1965). (17) McQuaker, N. R., Gurney, M., Report 50020, Environmental Lab, Dept. of Environment, Province of British Columbia, Canada, 1976.
(18) Water Resources Service, “Pollution Control Objectives for Mining, Mine-milling and Smelting Industries of British Columbia”, p 20, Province of British Columbia, Canada, 1973. (19) Dept. of Transportation and Communications,“Environmental Quality Users Information System (EQUIS)”,Province of British Columbia, Canada, 1975, 1976.
Received for review December 9, 1976. Accepted August 11, 1977.
Polynuclear Aromatic Hydrocarbons in Coal-Identification X-ray Excited Optical Luminescence
by Their
Ching S. Woo’, Arthur P. D’Silva, Velmer A. Fassel”, and Gregory J. Oestreich A m e s Laboratory-DOE, and Department of Chemistry, Iowa State University, Ames, Iowa 5001 1
Several polynuclear aromatic hydrocarbons were isolated from raw coal and detected by their characteristic x-ray excited optical luminescence spectra. Polynuclear aromatic hydrocarbons (PAH) occur in coal tar pitch ( I , 2 ) in the environment surrounding coke production ( 3 ) ,coal conversion processes, and in coal liquefaction products ( 4 - 6 ) . With the exception of 3,4-benzopyrene, which has been measured in various coal dusts (5, 6 ) , very little is known about the occurrence and distribution of PAH’s in various coal types. This characterization is a subject of considerable importance because of the carcinogenic nature of many PAH’s. With a projected greater utilization of coal as a major source of fuel, the carcinogenic PAH’s present in coal may pose a significant occupational health hazard. Recently, we reported the first observation of x-ray excited sharp-line fluorescence and phosphorescence (XEOL) emitted by a selected group of PAH’s present as trace constituents in n-heptane, a Shpol’skii solvent (7, 8 ) Previous studies on PAH’s present in environmental samples have utilized highpressure liquid chromatography or gas chromatography-mass spectroscopy t o isolate individual P A H compounds to facilitate their detection and quantification. These analytical techniques are elaborate, time consuming, and require expensive instrumentation. In contrast, the procedure described in this report is less elaborate and is designed t o accomplish multicomponent analysis on a sample extract without requiring the time-consuming prior isolation of individual PAH components.
gel (60-200 mesh, grade 950, Baker Chemical Co.) were activated overnight at 240 “ C and partially deactivated by the addition of weighed amounts of water t o yield a 3% moisture content. T h e P A H compounds were obtained from Eastman Kodak or Aldrich Chemical Co. and were used without further purification. Coal samples were obtained from the Ames City Power Plant and the Illinois Geological Survey. Extraction and Isolation of PAH Compounds. A modification of the procedure described by Giger and Blumer ( I O ) was used to separate the PAH’s from other compounds that may cause spectral interference or increase the spectral background. T h e modified procedure provided a relatively pure mixture of PAH’s within 30 h in contrast to the 72 h required by the original procedure. A 15-g coal sample was extracted for 24 h with 150 mL of benzene or cyclohexane in a Soxhlet extractor. The extract was
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Experimental Facilities a n d Procedures Apparatus. The XEOL spectrometric instrumentation has been described (7, 9). Reagents. All solvents used in this study were of spectra or ACS reagent grade (J. T. Baker Chemical Co. or Fisher Scientific Co.). Benzene was redistilled before use. No luminescence from impurities was detectable in these solvents. Sephadex LH20 (Sigma Chemical Co.) was washed with a methanol-benzene mixture (1:l)and packed in a column (1.5 cm i.d., 40 cm packed height). T h e same solvent mixture was used for washing the packed column. Chromatographic grade alumina (60-200 mesh, Matheson Coleman & Bell) and silica
’ Present address, Chemistry Department, University of Northern Iowa, Cedar Falls, Iowa 50613. 0013-936X/78/0912-0173$01.00/0
0 1978 American Chemical Society
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h3re1engti- irrr
Figure 1. X-ray excited optical luminescence spectra of five PAH’s each present at a level of 1 ppm in heptane before (lower) and after (upper) chemical processing of spiked coal samples 1 1,2-Benzanthracene 2 3.4-Benzopyrene 3 Coronene 4 Perylene 5 Phenanthrene
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concentrated in a rotary evaporator to a volume of 5 mL, and the concentrate percolated through a column of freshly prepared precipitated copper (1.0 cm i.d. and 20 cm packed height) and eluted with a n-heptane-benzene mixture (2:1) to remove elemental sulfur. The solvent in the eluate was evaporated in a rotary evaporator a t temperatures
