in “Trace Substances in Environmental Health-VII”, D. D. Hemphill, Ed., pp 161-6, Univ. of Missouri Press, Columbia, Mo., 1973. (29) Kleinman, M. T., Bernstein, D. M., Eisenbud, M., Kneip, T. J., “Seasonal and Source Relationships for Urban Suspended Particulate Matter and Trace Element Concentrations in New York City”, Paper No. 75-14.4,presented at 68th Annual Meeting of the Air Pollution Control Assoc., Boston, Mass.,June 1975. (30) Kleinman, M. T., Kneip, T. J.,Eisenbud, M., Atmos. Enuiron., 10,9-11 (1976).
(31) Snedecor,G. W., Cochran, W. G., “Statistical Methods”, 6th ed., p 400, Iowa State Univ. Press, Ames, Iowa, 1967. (32) Ezekiel, M., Fox, K. A., “Methods of Correlation and Regression Analysis”, 3rd ed., p 192, Wiley, New York, N.Y., 1959.
Receiued for reuieui June 28, 1976. Accepted December 27, 1977. Study supported by the National Science Foundation under Grant AEN74-17624 A01.
Isolation and Identification of Some Thermal Energy Analyzer (TEA) Responsive Substances in Drinking Water Tsai Y. Fan*, Ronald Ross, and David H. Fine Thermo Electron Research Center, 85 First Avenue, Waltham, Mass. 02154
Lawrence H. Keith’ and Arthur W. Garrison Environmental Research Laboratory, Environmental Protection Agency, Athens, Ga. 30605
Thermal Energy Analyzer (TEA)-responsive substances were found in the methylene chloride extracts of finished water samples from the water treatment plants in Cincinnati, Washington, and Philadelphia when they were analyzed by high-pressure liquid chromatography. The TEA-responsive substances, one from Cincinnati, two each from Washington and Philadelphia, were isolated and characterized by various instrumental techniques. Ethylene glycol dinitrate was identified in the isolates from the finished water in all three cities. The results of this study suggest that TEA response in any given sample should not be taken as presumptive evidence for the presence of a n N-nitroso compound. Independent identification techniques are needed t o confirm the identity of the suspected compounds. The Thermal Energy Analyzer (TEA) is a n N-nitroso detector that is based on the catalytic cleavage of the thermally labile N-NO bond and the subsequent detection of the nitrosyl radical by its reaction with ozone ( I ) . T h e TEA can be interfaced to a gas chromatograph (TEA-GC) for volatile N-nitroso compound analysis ( 2 ) or t o a high-performance liquid chromatograph (TEA-HPLC) for analysis of both volatile and nonvolatile N-nitroso compounds ( 3 ) .Although not exclusively specific for N-nitroso compounds, only N nitroso and some C-nitroso compounds, organic nitrites, and organic nitrates generally exhibit cleavage of the nitrosyl radical under the conditions of the TEA detector. T h e detector is also highly sensitive. Determination of volatile N nitrosamines in water a t the part per trillion level has been demonstrated ( 4 ) . Dimethylnitrosamine (DMN), probably of industrial origin, has been detected at levels of 0.08-2.7 pg/L in Curtis Bay, Baltimore by TEA-GC ( 5 ) . Many naturally occurring and man-made precursors of N-nitroso compounds, i.e., amines and nitrite, are present in water where N-nitroso compounds may be formed. TEAHPLC revealed the presence of at least 24 TEA-responsive compounds in drinking water from New Orleans, La., although no responses were obtained with this water a t a detection level of 0.002 wg/L using TEA-GC (6).The present communication reports the isolation and identification of several TEA-responsive compounds from drinking water in Cincinnati, Washington, D.C., and Philadelphia. Present address, Radian Corp., Austin, Tex. 78766. 692
Environmental Science & Technology
Experimental Apparatus. The high-performance liquid chromatograph (HPLC) was constructed by combining a high-pressure pump (Model 6000A, Waters Associates, Milford, Mass.) with an injector (Model U6K, Waters Associates). pPorasil or pBondapak CN columns were used (30 cm X 4 mm, Waters Associates). The effluent from the column was connected to either a UV detector (Model 440, Waters Associates) monitoring absorbance a t 254 nm or a Thermal Energy Analyzer (Model 502LC, Thermo Electron, Waltham, Mass.). Solvents. Glass-distilled solvents (Burdick and Jackson, Muskegan, Mich.) were used throughout this study. Water Sources. Drinking water samples a t various treatment stages were collected a t the water treatment plants in Cincinnati (May 4-7, 1976), Washington, D.C. (May 11-14, 1976) and Philadelphia’s Torresdale, Belmont, and Queen Lane plants (May 17-19, 1976). The Ohio River, Potomac River, and both the Delaware and Schuylkill Rivers supply raw water to treatment plants of Cincinnati, Washington, and Philadelphia, respectively. Although there is some variation in each plant, the method of water treatment is similar. The water samples were defined as follows: raw water is water pumped from the river to a reservoir for treatment. I n f l u e n t is raw water that has been chlorinated and flocculated and is t o be filtered. E f f l u e n t is influent that has been filtered through beds of sand and gravel. Finished water is effluent that has been treated chemically to be suitable for public consumption. The treatment may include chlorination, metaphosphate treatment, fluoridation, and ammonia treatment. T a p water is finished water collected a t consumer outlets. Analysis. Water samples (1L) were extracted three times with 50 mL of dichloromethane (DCM). The DCM layers were drained, combined, and concentrated in a Kuderna-Danish evaporator to less than 1 mL. The concentrated extracts were analyzed by TEA-HPLC using a pPorasil column with acetone/hexane (5/95) as the elution solvent a t a flow rate of 2 mL/min. Preparative Isolation of TEA-Responsive Substances Preparation of XAD Resin Cartridges. XAD-4 resin (Rohm and Haas, Philadelphia, Pa.) required extensive washings and sizing before it could be used. A slurry of XAD-4 resin in 5% aqueous sodium carbonate was allowed t o stand a t least 4 h. The slurry was filtered, and the resin rinsed suc-
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cessively with 0.1 N hydrochloric acid and water. The resin was washed in a Soxhlet apparatus for 8 h with each of the following solvents in sequence: water, methanol, acetone, and DCM. Finally it was sieved as an aqueous slurry to retain 20-40 mesh resin particles. XAD-8 resin was substantially cleaner than XAD-4 resin when received (Rohm and Haas). The washings were carried out in a flask only. The resin slurry was rinsed in diluted base and acid as described above. The resin was then washed successively with one resin volume of methanol, methylene chloride, acetone, and four volumes of distilled water. No sieving was required since this resin was sufficiently uniform in particle size. The resin cartridge was prepared by packing 2 L of a mixture of XAD-4 and XAD-8 (2:1, v/v) in a 40 X 12 cm glass column. A stainless steel screen, gravel, and glass wool were placed at each end of the resin bed. During water sampling, the glass wool was changed when large particles clogged it and reduced the flow rate. Extraction of Organic Substances from Resin. The resin cartridge was allowed to drain at ambient pressure. The resin was washed out of the column with one resin volume of acetone, and the slurry was allowed to stand for at least 1 h. The slurry was filtered, and the resin washed with one-half resin volume of acetone followed by one resin volume of methylene chloride. When the acetone and methylene chloride washings were combined, phase separation resulted due to the presence of water. The organic phase was removed, and the aqueous phase was extracted twice with an equal volume of methylene chloride. The crude extract consisted of the combined organic phases. Cleanup of Crude Extract. The crude extract was concentrated to dryness a t 40 "C in a rotary evaporator. The residue was dissolved in 50 mL of methylene chloride and successively washed with 0.1 N sodium hydroxide and 0.1 N hydrochloric acid. The washed extract was filtered through sodium sulfate and concentrated in a Kuderna-Danish evaporator to approximately 2 mL; 500 pL or less of this concentrate was loaded onto a 12 X 0.7 cm alumina column (60-70 mesh, Analab, North Haven, Conn.). The column was eluted with 6 mL of hexane followed by 6 mL of methylene chloride/acetone (l/l).The methylene chloride/acetone eluate was concentrated to 1mL and loaded onto a 25 X 2.5 cm silica
I
I
i
I
I
!
I
lII MIYUIES
MINJTES
MINUTES
chromatograms of dichloromethane extract of drinking water from (a) Cincinnati, (b) Washington and (c) Philadelphia Figure 1. TEA-HPLC
Column, pPorasil (30 X 4 cm); eluent, acetonelhexane 5/95; flow rate, 2 mllmin
gel column (60-200 mesh, Applied Science, State College, Pa.). The column was eluted successively with 100 mL each of hexane, hexane/acetone (4/1) hexane/acetone (3/2), and acetone. The flow rate was 7 mL/min. A fraction was collected for 1 min, and aliquots were injected directly into the TEA. The fractions with positive response on the TEA were chromatographed on TEA-HPLC. Similar fractions were pooled and concentrated to approximately 1 mL. Isolation of TEA-Responsive Substances. The concentrates, 50-100 pL each, were loaded onto a WPorasil column and eluted with acetone/hexane (5/95) a t a flow rate of 2 mL/min. A "tee" that permitted only 5% of the column effluent to enter the TEA was installed at the end of the column to allow collection of the bulk of the effluent. Center cuts of TEA peaks were collected and concentrated, and the HPLC isolation procedure was repeated twice to increase the purity of the TEA-responsive materials. After TEA-responsive substances were isolated a t the Thermo Electron Research Center, the isolates were hand carried in sealed glass vials to the U S . Environmental Protection Agency, Environmental Research Laboratory in Athens, Ga., for characterization.
Results TEA-HPLC chromatograms of finished water extracts appear in Figure 1. In addition to the solvent front in the chromatograms, there were one, two, and two conspicuous peaks in the water extracts of Cincinnati, Washington, and Philadelphia, respectively. The estimated concentration of each compound is presented in Table I. The TEA-responsive
Table 1. Some TEA Peaks in Drinking Water of Cincinnati, Washington, and Philadelphia at Different Treatment Stages Retention time relative to dimethylnitrosamine on HPLC-TEA 0.73 Water sample
RRT 1.04 Concentration In nmol/La
Cincinnati Raw water 1.5 Influent 2.5 Effluent 2.0 Finished water 2.0 (A-3)' Tap water 3.5 Washington Raw water 87.5 Influent 74.0 67.5 Effluent Finished water 87.5 (A-2)' Tap water 182.0 Philadelphia-Belmont plant Raw water 20.0 Influent 250.0 Effluent 121.5 Finished water 330.5 ( A - l ) C Tap water 742.5 Philadelphia-Queen Lane plant Raw water 6.5 Finished water 216.0 Philadelphia-Torresdale plant Raw water nd Pinished water nd
1.13
nd nd nd nd nd
nd
1.2 1.2 1.3
1.3 (C)' 2.7
nd nd nd nd nd
nd nd nd nd
nd 0.8 0.8 1.9 (B) '
nd
6.7
nd nd
nd 1.1
nd nd
nd nd
nd nd nd nd
a The peak at RRT 0.73 was identifiedas ethylene glycol dinitrate, the molar response of which on TEA was 20% of dimethylnitrosamine (DMN). The peaks at RRT 1.04 and 1 13 were not identified, and the concentrations were estimated assuming equal response to DMN. Not detected. Isolates for characterization-see Table II.
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Table II. Characterization of TEA Peaks (RRT = 0.73) Isolated from Finished Drinking Water of Cincinnati, Washington, and Philadelphia (Belmont) TEA peak
city
EGDN
Standard Philadelphia Washington Cincinnati
A- 1 A-2 A-3
FID
EGDN EGDN EGDN EGDN
Gas chromatographlc detector a HECN El-MS
EGDN EGDN EGDN EGDN
EGDN EGDN e e
CI-MS
HPLC-TEA
EGDN EGDN e
EGDN EGDN EGDN EGDN
e
IR (KBr Pellet)
EGDN EGDN f f
a FID, flame ionization detector: HECN. Hall electrolytic conductivity nitrogen detector: El-MS, electron impact mass spectrometer; CI-MS, chemical ionization mass spectrometer. Ethylene glycol dinitrate. IR spectrum confirmed dinitrate ester functional groups. The isolate was not completely pure. Other compounds, including atrazine, were detected. a Concentration of the compound in the isolate was too low to allow detection. 'Not investigated.
compounds listed here were those that eluted with acetone/ hexane (5/95) solvent system from the KPorasil column. Very nonpolar compounds that eluted with or near the solvent front and highly polar compounds that did not elute with the solvent system were not investigated. The compound with a relative retention time (RRT) of 0.73 as compared to dimethylnitrosamine (DMN) was present in all water samples except those from the Torresdale plant in Philadelphia. In all cases, the concentration of this compound in water increased during the water treatment; the levels were invariably much higher in tap water than in the raw water. The concentration in tap water seemed to depend on the initial concentration in raw water (Le., the river source) and the method of treatment. The concentration of this compound was very low in water samples from the Cincinnati plant throughout all stages of treatment. I t was not detected in either raw water or finished water from the Torresdale plant. However, this compound was present in raw water from the Belmont plant (Philadelphia) a t a level of 20 nmol/L and increased to 743 nmol/L in tap water-an almost fortyfold increase. Water from Queen Lane plant (Philadelphia)showed a similar pattern. I t should be noted that the three plants in Philadelphia obtain their raw water from different sources; the Torresdale plant is supplied by the Delaware River, while both the Belmont and Queen Lane plants are supplied by the Schuylkill River. The compound with a RRT of 1.04 was found only in water samples from the Washington plant while the compound with a RRT of 1.13 was found only in water samples from the Belmont and Queen Lane plants. The concentrations of both compounds also increased as the water treatment progressed. Five TEA-responsive compounds or mixtures were thus isolated from the finished water at the water treatment plants; A-1 (RRT 0.73) and B (RRT 1.13) were isolated from the Belmont plant, A-2 (RRT 0.73), C (RRT 1.04) was isolated from the Washington plant, and A-3 (RRT 0.73) from the Cincinnati plant. Isolate A-1, which was GC amenable and abundantly available, has been extensively characterized (Table 11). After separation by gas chromatography, it was tentatively identified as ethylene glycol dinitrate (EGDN) by electron impact mass spectrometry (EI-MS) and chemical ionization mass spectrometry (CI-MS). For EI-MS, a 3% OV-17 glass column, in. i.d. X 10 ft, was used. The injector temperature was between 70 and 100 "C, with the column temperature increased from 25 to 150 "C at a rate of 6"/min. Mass spectra were obtained with a Finnegan 3200 instrument, with the ion source operated a t 70 eV. For CI-MS, a SP2100 glass capillary column, 0.4 mm i.d. X 33 m long, was used. Carrierheagent gas was methane, with an indicated source pressure of 800 1.Mass spectra were obtained with a Finnegan 3200 instrument a t 110 eV in the chemical ionization mode. An authentic EGDN standard was 694
Environmental Science & Technology
obtained (courtesy of L. Elias, Unsteady Aerodynamics Lab., National Aeronautical Establishment, National Research Council, Ottawa, Canada), and isolate A-1 was confirmed as EGDN when compared to the standard by several techniques (Table 11). Isolates A-2 and A-3, which also eluted at RRT 0.73 on HPLC, were not isolated in large enough quantity for confirmation by MS. Therefore, only the flame ionization detector (FID), Hall electrolytic conductivity nitrogen (HECN) detector and TEA-HPLC confirmed both isolates as EGDN. A 3% SP-2100 or OV-17 glass column, 1/8 in. i.d. X 10 ft, was used as the GC column for the FID. The injector was maintained at 90 "C. The column was temperature programmed from 25 to 150 "C a t 6'/min. For the HECN, a 1/8 in. X 6 f t glass column of 10% DC-200 was used with the injector a t 90 "C. The column was operated isothermally a t 95 "C. Neither isolate B nor C gave a response on the GC-TEA beyond the solvent front. However, GC analysis using a HECN detector indicated a t least three nitrogen-containing contaminants in isolate C. Two of the contaminants were identified as atrazine and EGDN; the latter could be contamination from the RRT 0.73 peak. The third nitrogen component was not identified. Isolate B showed a few small GC peaks using a flame ionization detector, but no GC peaks were observed with either the TEA or HECN detector. Solid probe mass spectrometry was not attempted for these two isolates since experience with isolate A-1 indicated that impurities would mask most of the fragments of the compounds of interest. However, HPLC-UV analysis a t a wavelength of 254 nm indicated both isolates B and C were not likely to contain any N-nitroso compounds. N-nitrosamines have a characteristic absorption maximum between 230-240 nm ( 7 ) ,and the UV absorptivities of both isolates were about 100 times lower than that of DMN a t 254 nm. However, both peaks B and C could be similar to EGDN structurally, as their UV absorptivities a t 254 nm were equal to that of EGDN. The chemical identity of isolates B and C is not presently known.
Table 111. Molar Responses of Alkyl Nitrates and Nitrites to the TEA Detector, Relative to Dimethylnitrosamine
Compound
Dimethylnitrosamine Ethylene glycol dinitrate +Propyl nitrate Isopropyl nitrate n-Butyl nitrate Isoamyl nitrate +Pentyl nitrite lsopentyl nitrite
Relatlve molar response
1.o
0.2 0.7 0.7 0.8 0.9 1.o 1.o
In the course of this work, in addition to the positive response from EGDN, several other alkyl nitrates and nitrites were shown to give positive responses on TEA-HPLC that were similar to that of DMN (Table 111). Discussion All the evidence in this study indicated that the TEA-responsive compounds isolated from the finished drinking water from water treatment plants in Cincinnati, Washington, and Philadelphia were not N-nitroso compounds. EGDN was identified in the drinking water of all three cities. EGDN is an ingredient in explosives; this is the first time this compound has been reported to be present in drinking water. Whereas EGDN may be of industrial origin in the Cincinnati and Philadelphia water, it is probably not of agricultural or industrial origin in Washington since the Potomac River receives little agricultural waste upstream from Washington. However, the Potomac is contaminated by mine wastes, a possible source of traces of the explosive. Another possible source is nitration of ethylene glycol, which is a major ingredient of automobile antifreeze solutions. It is interesting to note that the EGDN concentration increased during the water treatment processes; possibly chemicals used to treat water catalyzed EGDN formation from its precursors. Although no N-nitroso compound was identified in any of the drinking waters in the present study, it should be noted that the compounds that were isolated were those soluble in methylene chloride and chromatographable by the solvent system of acetone/hexane (5/95) on a FPorasil column. Highly polar compounds such as N-nitrosodiethanolamine and nonpolar compounds would not have been observed. Furthermore, earlier extracts of New Orleans drinking water showed much more complex TEA chromatograms (6).Further study is needed to understand possible N-nitroso compound contamination in drinking water. The introduction of TEA has simplified the analysis of N-nitroso compounds in other complex systems. Successful application of TEA for the detection of N-nitroso compounds with subsequent identification of these compounds by mass spectrometry in air ( 8 ) ,water ( 5 ) ,commercial herbicides (9) and synthetic cutting fluids (IO)has been reported. However, some classes of compounds other than N-nitroso compounds have been demonst rated to contain a thermally labile nitrosyl group that can give a positive response to TEA (1).Recently, Stephany and Schuller (11) reported that some tertiary alkyl C-nitroso compounds may yield positive responses to TEA. In this laboratory, in addition to the positive response from EGDN, several other alkyl nitrates and nitrites were shown to give 0.7-1.0 molar responses on TEA-HPLC relative to
DMN (Table 111). All compounds that have labile nitrosyl groups can respond to the TEA, and unrestrained interpretation of TEA analytical results can lead to misidentification. I t is essential that independent techniques such as IR and mass spectrometry be employed to confirm the identity of every new compound giving a positive TEA response. Acknowledgment We are indebted to the technical staff of the water treatment plants in Cincinnati, Washington, and Philadelphia for their extensive cooperation during water collection and sampling; John Morrison and Morris Tobiri of Thermo Electron Research Center for technical assistance; Alfred Thruston (LC analysis), Mike Carter (MS analysis), Terry Floyd (FID-GC analysis), John Pope (HECN-GC analysis), and Leo Azarraga (IR analysis), all of the Environmental Research Laboratory, Athens; and also Ron Webb, of the same laboratory, for technical advice. Literature Cited (1) Fine, D. H., Rufeh, F., Lieh, D., Rounhehler, D. P., Anal. Chem.,
47,1188 (1975).
H., Hounbehler. D. P., J . Chromatopr.. - . 109. 271 (1975): (3) Oettinger, Y . E., Huffman, F., Fine, D. H., Lieh, D., Anal. Lett., 8, 411 (1975). (4) Fine, D. H., Rounbehler, D. P., Huffman, F., Garrison, A. W., Wolfe, N. L., Epstein, S. S., Bull. Enuiron. Contam. Toxicol., 14, 404 (1975). (5) Fine, D. H., Rounhehler, D. P., in “Identification and Analysis of Organic Pollutants in Water,” L. H. Keith, Ed., Chap. 17, Ann Arbor Science, 1976. Fine, D. H., Rounhehler, D. P.. Rounhehler, A., Silvergleid, A,, Sawicki, E., Krost, K., De Marrais, G. A,, Enuzron Scz Techrbol., 11,581 (1977). (6) Fine. D. H.. Rounbehler. D. P.. Belcher. N. M.. h s t e i n . S. S.. “Proceedings’ of International Conference on ‘Environmental Sensing and Assessment,” Vol2, Chap. 30, Institute Electrical and Electronics Engineers, New York, N.Y., 1975. (7) Eisenbrand, G., Spaczynski, K., Preussman, R., J . Chromatogr., 51,503 (1970). ( 8 ) Fine, D. H., Rounbehler, D. P., Belcher, N. M., Epstein, S. S., Science, 192, 1328 (1976). (9) Ross, R., Morrison, J., Rounbehler, D. P., Fan, S., Fine, D. H., J . Agric. Food Chem., 25,1416 (1977). (10) Fan. T. Y.. Morrison. J.. Rounbehler. D. P.. Ross., R.., Fine. D. H., Science, 196, 70 (1977): (11) Stephany, R. W., Schuller, P. L., in “Proceedings of the Second International Symposium on Nitrite in Meat Products,” B. J. Tinbergen and B. Krol, Eds., p 249, Center for Agricultural Publishing and Documentation, Wageningen, The Netherlands, 1977.
( 2 ) Fine. D.
Received for reuiew September 30,1977. Accepted December 27,1977. Work supported by the Enuironmental Protection Agency under Grant No. 68-03-2400.
EnvironmentalAspects of a Well Blowout in the Gulf of Mexico James M. Brooks”, Bernie B. Bernard, Theodor C. Sauer, Jr., and Hussein Abdel-Reheim Department of Oceanography, Texas A&M University, College Station, Tex. 77843
Well blowouts and, in particular, platform losses are rare occurrences during offshore drilling operations. They are, however, the inevitable result of accidents where heavy equipment, flammable materials, large numbers of employees, and large-scale reliance on complex technology are involved. In some cases, these catastrophic incidents can result in large inputs of gaseous and/or liquid hydrocarbons into the marine environment. One such major offshore incident occurred about 100 miles south of Galveston during early November 0013-936X/78/0912-0695$01.00/0
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1978 American Chemical Society
1976 in High Island South Addition Area. A fixed drilling platform located in 95 m of water was lost following a well blowout. Sea Technology (1) reported this was probably the first time a well blowout caused a fixed drilling platform to collapse. The blowout occurred during drilling of the fifth well from the platform. Some of the previous wells had penetrated to over 3000 m, and the fifth well was over 1800 m when well control was lost (1).The platform collapse resulted from the Volume 12, Number 6, June 1978
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