obtained with much improved resolution, demonstrate that automobile exhaust and environmental PAH mixtures are far more complex than was assumed in the past. Therefore, earlier analyses now appear much more limited in their power to correlate with, or to predict, public health effects. Numerous additional components of exhaust and of environmental samples must now be considered in their possible roles as carcinogens, tumor inducers or promoters, and mutagens. The demonstrated correlation between highway traffic and the production of carcinogens strengthens indirectly also the correlation between highway traffic and the observed mortality from cancer. The implications for public health, for city and highway planning, and for efforts to control engine exhaust are considerable.
Literature Cited (1) Blumer. W.. Jaumann, R., Reich, Th., Schueiz. Rundsch. Med. Prar., 61,514-18 (1972). (2) Giger, W., Blumer, M.,Anal. Chem., 46,1663-71 (1974). (3) Blumer. M.. Finnimn SDectra, 5 (3) (1975). (4) Youngblood, W. W., Blimer, M., Geochim. Cosmochim. Acta, 39,1303-14 (1975). ( 5 ) Blumer, M., Sei. Am., 234,34-45 (1976). (6) Blumer, M., Chem. Geol., 16,245-56 (1975). (7) Greinke, R. A., Lewis, I. C., Anal. Chem., 47,2151-55 (1975). (8) Blumer, M., Youngblood, W. W., Science, 188,53-55 (1975).
Received for reuieu January 3,1977. Accepted May 26,1977. Work at Woods Hole supported by the Office of Naval Research (NOO14-66 Contract CO-241) and the National Science Foundation (Grant DES 74-22781).
Determination of Elemental Sulfur by Gas Chromatography John J. Richard, Raymond D. Vick, and Gregor A. Junk* Ames Laboratory-ERDA,
Iowa State University, Ames, Iowa 5001 1
Elemental sulfur was determined by combining electron capture detection with cyclohexane extractions of coal, particulate, and soil samples and with resin sorption of water samples. The sensitivity for sulfur permitted its determination in environmental samples a t sub parts per billion levels. The extraction procedures allowed for a minimum of cleanup prior to the rapid and selective gas chromatography. The usual procedures for the determination of elemental sulfur are reduction to the sulfide or oxidation to the sulfate. These techniques generally lack the selectivity and sensitivity of reported gas-liquid (1-7), thin-layer (8),and liquid chromatographic (9)procedures. These are apparently useful for sulfur determinations, but none has been applied to the quantitation of elemental sulfur in environmental samples. This paper describes the methodology for the determination of elemental sulfur in stack particulate, soil, coal, and water samples using gas-liquid chromatography for the separation from other components present in the sample and electron capture for the selective and sensitive detection.
Experimental Apparatus. A Tracor Model 550 equipped with a Ni 63 electron capture detector (ECD) and a Beckman Model GC-5 equipped with a helium discharge ECD were used for the gas chromatography. Glass columns, 2 m X 4 mm i.d., were packed with the solid supports and liquid phases listed in Table I. These columns were silanized with four injections of 25 pL each Silyl8 (Pierce Chemical Co.) before use. A Du Pont 21-490-1 gas chromatograph-mass spectrometer (GC-MS) was used for positive identifications of the elemental sulfur extracted from various environmental samples. Reagents. Cyclohexane (J. T. Baker Chemical Co.), 98Y0 grade, was further purified by distillation. Sulfur standards used for quantitation were prepared by volumetric dilution of a solution having 10 mg of 99.999% sulfur in 50 mL of cyclohexane. The 60-100 mesh Florisil (Floridin Co.) used to clean up the sample extracts was calcined a t 540 "C by the manufacturer and activated for 5 h a t 130 "C prior to use. 1084
Environmental Science & Technology
Analytical Procedures Coal, Particulate, and Soil Extractions. One-gram samples of crushed coal which had passed a 60 mesh sieve were Soxhlet extracted for 24 h. Large 35 X 90 mm glass thimbles were used to prevent plugging of the Soxhlet device by the fines from the coal samples. The 90 mL of cyclohexane used for the extraction were then quantitatively transferred to volumetric flasks and diluted to 100 mL. Five-pL aliquots of this cyclohexane solution were subjected to gas chromatography without further cleanup. Particulate samples were collected from 4-in. sampling ports located approximately half-way up the stack of a local power plant. Three types of samples were collected. Particulates # 1were from the accumulation in the ports. Particulates # 2 were collected by drawing the atmosphere from inside the stack through a glass tube containing a glass wool plug. Particulates # 3 represented that portion which settled onto horizontal trays placed inside the stack. Ten grams of particulates were extracted in a Soxhlet for 24 h in 25 X 85 mm glass thimbles using approximately 50 mL of cyclohexane. The cyclohexane was transferred to volumetric flasks and diluted to 50 mL with cyclohexane. Five-pL aliquots of this solution were gas chromatographed without further cleanup. Ten-gram amounts of local soils were Soxhlet extracted with cyclohexane as above. The extracts were concentrated Table 1. Gas Chromatographic Data for Elemental Sulfur Llquld phase
5% 4% 6% 3%
OV-210b SE-30/ OV-210b OV-lb
5%
ov-1
1.5% OV-17/ 1.95% OV-210' 10% DC-200'
Solld supporta
t ~ , mln
Column temp, OC
Flow, rnL/rnln
C
2.3
180
75
G C C
5.2 1.7 1.8
200 120 120
75 75 75
G G
2.5 3.6
200 200
160 160
C is Chromosorb W HP, 80-100 mesh: G is Gas Chrom Q.100-120 mesh. Tracor Model 550; detector, 340 OC;injector, 220 O C . Beckman GC-5; detector, 310 OC;injector, 240 O C .
r-r
to approximately 2-3 mL and transferred to an 8-mm 0.d. Pyrex glass column containing 2-3 cm of activated Florisil. The columns were eluted with cyclohexane to give an eluate volume of 10 mL. Five-pL aliquots of these solutions were gas chromatographed. Water Extractions. Sulfur was extracted from water by the resin sorption procedure ( 1 0 , l l ) .Four liters of water were passed through an 8 X 100 mm glass column containing 6 cc of 40-60 mesh XAD-2 resin (Rohm and Haas). The sorbed sulfur was eluted from the resin with 25 mL of diethylether which was then dried and concentrated to approximately 1 mL. The concentrate was transferred to the small 2-3-cm Florisil column which was then eluted with 5 mL of cyclohexane. The eluate was concentrated to 1mL, and 5-pL aliquots of this solution were gas chromatographed. The recovery of sulfur from water spiked a t 10 pg/L was 85%efficient using this procedure.
I
I
Lc w
g
I
w
a
1
Discussion Vaporization and mass spectrometry studies have shown the dominant species present in sulfur vapor between 100 and 250 "C to be Sg (12).This corresponds to what was found by GC-MS analysis of cyclohexane extracts and by direct insertion MS analyses of the sulfur residual after evaporation of the cyclohexane from environmental extracts and from standard solutions of sulfur in cyclohexane. The electron capture gas chromatogram of sulfur in Figure 1 shows only one major peak due to S8 which elutes a t -5.2 min. As shown in Figure 2 the chromatogram of a freshly prepared sulfur solution exhibits two early eluting minor peaks in addition to the major S8peak. These minor peaks are also present in the chromatograms of extracts from stack particulates. The identity of these peaks has not been resolved, but GC-MS data suggest that they are lower subspecies of sulfur. Efforts to identify these species positively have been inconclusive. The minor peaks are not present in the chromatograms from sulfur solutions stored for an extended period of time. This corresponds to what is suggested in the literature (13)where orthorhombic sulfur, S8,is formed from all other modifications of sulfur because it is the only stable form a t room temperature. The various liquid phases listed in Table I were checked for applicability to the gas chromatography of sulfur. The early elution observed on different liquid phases a t the listed temperatures and flow rates allows for rapid analyses. The detection limit for sulfur was less than 5 X 10-lo g regardless of the liquid phase employed, but there was some variation in ECD response for equivalent amounts of sulfur injected oncolumn. In some cases, this variation has been shown to be due to the past history of the column. The most dramatic example of column history affecting the response was the failure to observe a sulfur peak on a SE-30/OV-210 column which had previously been used to separate chlorinated phenols. Even resilanization could not restore the utility of this column for sulfur analyses. Cyclohexane was an ideal solvent for use in the Soxhlet extraction of sulfur from coal, soil and particulate samples. Electron capture interfering materials are not observed which obviates the usual cleanup procedures. A second extraction with cyclohexane indicated the first extraction was essentially complete. XAD-2 was ideal for the accumulation of sulfur from water samples. However, humic material in the soil and water interfered with the chromatography of sulfur; therefore, these materials were removed by passing the sample extracts through a small column of Florisil. Some data on the analyses of coal, particulates, soil, and water are given in Tables 11-V to demonstrate the general
C
2
4
1
5
1
8
T I M E , MINUTES
g elemental sulfur in cyclohexane Figure 1. Chromatogram of using 4 % SE-30/6% OV-210. Conditions listed in Table I
LL
f a LL
Figure 2. Chromatogram of g freshly prepared elemental sulfur in cyclohexane using 5 % OV-210. Conditions listed in Table I
Table II. Elemental Sulfur Content of Coal Coal source
d
Iowa # 1 Iowa #2 Iowa #3 Iowa #4 Wyoming Illinois
g
1000 2080 280 205 160 398
Table 111. Elemental Sulfur Content of Particulates Type a
#1 #2
#3 a
No. of samples
Range,
Av, wg/g
3 2 10
150-250 65-87 4-15
198 76 9
See text.
Volume 11, Number 12, November 1977
1085
Literature Cited
Table IV. Elemental Sulfur Content of Soils
(1) Pearson, J. R., Aldrich, F. D., Stone, A. W., J. Agric. Food Chem.,
Range, Pg/g
NO. Of
sampler
5
15,938-9 (1967). (2) Osadchuk, M., Wanless, E. B., J . Assoc. Off. Anal. Chem., 51 (6),
1-16
applicability of the methodology for measuring sulfur in environmental samples. In each case, the analytical reproducibility is better than &lo%. The data show sulfur to be an expected ubiquitous contaminant.
1264-7 (1968). (3) Ahling, B., Jensen, S., Anal. Chem., 42 (131,1483-6 (1970). (4) Struble, D. L., J . Chromatogr. Sei., 10,57-9 (1972). (5) Strosher, M. T., Hodgson, G. W., “Water Quality Parameters”, pp 259-70, ASTM STP573, American Society for Testing Materials, 1975. (6) Junk, G. A,, Stanley, S. E., “Organics in Drinking Water. Part 1. Listing of Identified Chemicals”,Ames Laboratory, ERDA IS-3671, July 1975. (7) Hites, R. A,, Biemann, W. G., Gibbs, T.R.P., Jr., Eds., “Analytical Methods in Oceanography”,Advances in Chemistry Series, No. 147, pp 188-201, ACS, Washington, D.C., 1975. (8) Banaszkiewicz, S.. Microchem. J., 21,306-8 (1976). (9) Cassidy, R. M., J . Chromatogr., 117,71-9 (1976). (10) Junk, G. A., Richard, J . J., Grieser, M. D., Witiak, D., Witiak, J. L., Arguello, M. D., Vick, R., Svec, H. J., Fritz, J. S.,Calder, G. V., ibid., 99, 745-62 (1974). (11) Richard, J. J., Junk, G. A., Avery, M. J., Nehring, N. L., Fritz, J. S., Svec, H. J., Pestic. Monit. J., 9 (3), 117-23 (1975). (12) Berkowitz, J., Meyer, B., Eds., “Elemental Sulfur”, Chap. 7, Interscience, New York, N.Y., 1965. (13) Schmidt, M., Siebert, W., Trotman-Dickenson, A. F., Eds., “Comprehensive Inorganic Chemistry”, Vol 2, Chap. 25, Pergamon Press, Elmsford, N.Y., 1973.
Acknowledgment The leadership of H. J. Svec, J. S. Fritz, and H. R. Shanks and the instrumental work of M. J. Avery are greatly appreciated.
Receiued for recieu: January 17,1977. Accepted May 31,1977. Work supported by the U.S. Energy Research and Development Administration, DiLision of Physical Research, under base program R T 04-03. Equipment used procured through N S F grants GP33526X and GP42252.
Table V. Elemental Sulfur Content of Water Location
Little Wall Lake Skunk River (Sept. 1) Skunk River (Nov. 1 5 ) a Skunk River (Nov. 15) Squaw Creek Hickory Grove Lake Coal washing planta
PUL
0.3 9.5 1.0 1.1 0.1 0.1
38.0
Water filtered through sintered glass (2-3 pm).
Input and Fate of Petroleum Hydrocarbons Entering the Providence River and Upper Narragansett Bay from Wastewater Effluents Edward S. Van Vleet” and James G. Quinn Graduate School of Oceanography, University of Rhode Island, Kingston, R.I. 02881
w A one-year background survey of the petroleum hydrocarbons discharged to the Providence River by a municipal wastewater secondary treatment plant indicated that these plants may be significant contributors to oil pollution in estuarine and coastal waters. The hydrocarbons were discharged primarily in association with the suspended solids. Analysis of suspended material and sediments in the river and upper Narragansett Bay indicated that approximately half of the suspended hydrocarbons were rapidly sedimented out in the river, and the remainder were transported out of the river and throughout the bay. The petroleum products were persistent to 40 cm in some sedimentary cores with the subsequent emergence of biologically produced hydrocarbons indicating the extent to which oil pollution was present in these sediments.
By enacting the Federal Water Pollution Control Act Amendments of 1972 (P.L. 92-500), the US.Congress established a national goal of eliminating the discharge of pollutants into navigable waters by 1985. In 1973, however, the Federal Government also established that by 1977, the minimum treatment to be applied to all public wastewater discharges would be a secondary treatment process. Standards for this process, as defined by the Environmental Protection Agency, are based on biochemical oxygen demand, suspended 1086
Environmental Science & Technology
solids, fecal coliform bacteria, and pH (1).Unfortunately, the secondary treatment process is not designed to remove a significant amount of the petroleum hydrocarbons entering the treatment plant. As a result, the discharge of petroleum products in the wastewater effluent still poses an unresolved problem. I t has been estimated that domestic wastewater effluents can account for up to 5% of the total hydrocarbons entering the ocean annually (2-5), and the percentage entering coastal waters alone may be several times higher. Knowledge of the transport and fate of these hydrocarbons released into estuaries and coastal waters is essential in understanding their biological effects and geochemical cycles in the marine environment. Previous studies (6, 7) have shown that both fulvic and humic acids can fix and retain hydrocarbons by either incorporation into a molecular sieve-type structure or hydrophobic adsorption onto the surface of these humic materials. I t has also been reported (8,9)that up to ~ WofOthe organic material in sewage effluents may resemble humic substances. Consequently, these humic materials may play a major role in the transport and deposition of hydrocarbons introduced by wastewater effluents into estuaries and coastal waters. The present study was undertaken to investigate the input of petroleum hydrocarbons to the Providence River and upper Narragansett Bay (Rhode Island) by one municipal sewage treatment plant and to determine the transport mechanisms
