NOTES
Identification of 1,1,1,-Trichloroacetone (1,1,1-Trichloropropanone) in Two Drinking Waters: A Known Precursor in Haloform Reaction Irwin H. Suffet”, Lewis Brennerl, and Barry Silver2 Department of Chemistry, Environmental Studies Institute, Drexel University, Philadelphia, Pa. 19 104
1,1,1-Trichloroacetone (1,I,1-trichloropropanone),a known precursor in the haloform reaction, was isolated from the drinking water of two different river water supplies. An on-line XAD-2 macroreticular resin and a continuous liquid-liquid extractor were used as isolating techniques. The water was adjusted to near pH 4 before it was passed through the XAD-2 resin. GC/MS confirmation of the analysis is presented when free chlorination and/or ammoniation at two water supplies were practiced. Widespread interest was focused on the area of organic ‘contaminants in drinking water, with special emphasis on halogenated organics as a result of reports of Rook ( I ) , Bellar et al. ( 2 ) ,and in a preliminary draft of an EPA analytical report ( 3 ) .Rook (1)and Bellar et al. (2) found that the use of chlorine increased the concentration of certain halogenated organics in drinking water, as well as in the effluent of municipal treatment plants serving large industrial communities. Chloroform was formed in the greatest quantities, 5-10 times higher than any other volatile haloforms. Rook (1)presented the theory that the polyhydroxybenzene building blocks of the natural color molecules are responsible for the haloform reaction. Experimental models were used to support this mechanism. Bellar et al. (2) suggested a mechanism in which ethanol oxidizes to acetaldehyde, which subsequently reacts with free chlorine to form chloral. Chloral reacts with water to form chloral hydrate, which decomposes to form chloroform. Experimental evidence was not presented for this mechanism. Recently, EPA ( 3 )reported acetaldehyde was present in the drinking water of five cities-Miami, Seattle, Ottumwa, Cincinnati, and Philadelphia. Ethanol, acetaldehyde, and chloral were reported together in three cities-Seattle, Cincinnati, and Philadelphia. Morris ( 4 ) has reviewed the formation of the halogenated organics as well as recent experimental evidence from Rook. Rook found that the haloform productions directly from alcohol and acetone were too slow under ‘‘normal’’ water treatment plant operations. A few experiments were reported at a pH of 3.5 with some indication of reduced yield of haloforms, but there was no dramatic change. Building blocks of humic substances at the ppm level reacts with hypochlorite, e.g., resorcinol, a dihydroxybenzene, appears to exhibit the rate to account for the large production of haloforms a t the ppb level. The review article by Morris ( 4 ) described the state-of-the-art as, “Almost any accurate information related to the subject will be useful at least in providing orientation.” A reaction mechanism by which l,l,l-trichloroacetone and subsequently chloroform can be formed from acetone under aqueous alkaline conditions is reviewed by Morris ( 4 ) . SpeChemical Laboratory, Philadelphia Police Department, Philadelphia, Pa. Torresdale Laboratory, Philadelphia Water Department, Philadelphia, Pa.
cifically at 0 “C, pH 12.5-0.9, the rateconstant issecondorder with respect to the enol and OC1- species. Rate constants of 6.1-9.2 X 1. mol-l min-l for a 36 000 mg/l. acetone solution,have been measured by Bartlett ( 5 ) :The mechanisms indicate l,l,l-trichloroacetone is readily hydrolyzed to chloroform in neutral and basic solution. Our particular work on the study of isolation methods for organics from drinking water supplies developed evidence that l,l,l-trichloroacetone (1,1,1trichloropropanone) is present in the finished water tested to date. l,l,l-Trichloroacetone is a known precursor in the haloform reaction. The identification adds accurate information related to the subject of haloform formation.
Isolation Methods An XAD-2 macroreticular resin isolation technique based upon the method of Junk et al. (6) and a continuous liquidliquid extractor (CLLE) for qualitative analysis of trace organic compounds from water were utilized. The XAD-2 resin apparatus consisted of a 5 X 11 cm bed of 50/150 mesh resin (Rohm & Haas Co., Philadelphia, Pa.). The column is incorporated into an on-line apparatus to adjust the water to near pH 4 (with H3PO4) and to dechlorinate it (with NaZS03) before the water is fed through the resin bed a t a flow rate of 15-18 l./h (Table I). No dechlorination was observed when ammoniation was initiated for taste and odor control (Table I). The XAD-2 resin bed is eluted with 200 ml of ether (Burdick and Jackson, pesticide quality). The eluant is dried by anhydrous Na2S04 and concentrated 100 times by Kuderna-Danish evaporation. The CLLE apparatus is a modification of a previous design of a Teflon helix CLLE used for the extraction of organophosphate pesticides from water with benzene (7). The new CLLE system included solvent recycling by a new type continuous distillation system and dual Teflon helix extractor. The samples of tap water and solvent are pumped through two 0.063-in. i.d., 32-ft Teflon coils a t a water:chloroform ratio of 15:l from two dual-channel micropumps (Table I). Redistilled Fischer laboratory grade CHC13 was the solvent utilized. Gas ChromatographylMass Spectroscopy (GCIMS) The XAD-2 and CLLE extracts were analyzed on a Varian Model 1400 gas chromatograph coupled to a Finnigan Model 1015 S/L quadrapole mass spectrometer via a glass jet separator interfacing system. A splitter at the GC column effluent torr vacuum in the manifold. was adjusted to obtain 5 x The splitter was maintained throughout GC/MS analysis. A Systems Industries Model 150 data system was used to examine the spectra with hard copy available on a Houston Complot or Model 4631 hard copy unit on the Techtronix 4010-1 display unit. Mass spectrometer instrument conditions were: manifold temperature, 100 “C; ionizing voltage, 70 eV; filament current, 250 MA;electron multiplier, 3000 V; mass range, 25-300 amu; sensitivity, lop6 A/V; base integration time, 1 ms/amu. The delay time between scans was 5 s. Two different 3 f t X 0.085 in. i.d. stainless steel columns were used for the GCIMS analysis. They were packed with Volume 10, Number 13, December 1976 1273
20% SE-30 and 5%bentone 4 1 4 % didecyl phthalate, respectively; each was on 80/100 mesh Gas Chrom Q. The program temperature conditions for the SE-30 were: initial, 80 "C; final, 200 "C with a 6 "C/min program rate. The GC inlet temperature was set a t 250 "C. The helium carrier gas on SE-30 was adjusted to set the absolute retention time of 2-ethyl-1-hexanol to 9.0 min. The relative retention time of l,l,l-trichloroacetone to 2-ethyl-1-hexanol was 0.47. The programmed temperature conditions for the bentone-didecyl phthalate column were: initial, 70 "C; final, 120 "C with a 6 "C/min program rate after the initial temperature is held for 10 min. The GC inlet temperature was set at 125 "C. The helium carrier gas was adjusted to set the absolute retention time of toluene to 4 min. The relative retention time of l,l,l-trichloroacetone to toluene was 2.15.
Mass Spectra Identification Computer-assisted interpretation of mass spectral data was accomplished using Cornel1 University's mass spectral identification system PBM (probability based matching system) (8) and STIRS (self-training interpretive and retrieval system) (9).PBM is a reverse search technique and examines the uniqueness of each m/e value in the reference file. It attempts to "fit" the reference spectra into the unknown. STIRS uses a more complex algorithm for correlation of unknown and reference spectra. A series of 13 match factors sensitive to certain substructures is outputted. STIRS may not necessarily output the true compound, but the substructure consistent with the spectrum should be represented in the results.
Results 1,1,1-Trichloroacetone (1,1,1-trichloropropanone) was isolated by XAD-2 macroreticular resin from drinking water adjusted to pH 4. I t was identified by GC/MS in five separate samples of drinking water from the Torresdale Water Purification Plant of the City of Philadelphia, located on the Delaware River (Table I). All five samples were confirmed on the SE-30 column by GC/MS. The 4/17 sample was also confirmed on the bentone-didecyl phthalate column by GC/MS. Apparently, l,l,l-trichloroacetone was stabilized by adjustment to pH 4 during the XAD-2 sampling procedure. Subsequent to this study, l,l,l-trichloroacetone was confirmed to be present in a sample of drinking water collected 8/20-21/75 from the Belmont Water Purification Plant of the
City of Philadelphia located on the Schuylkill River by XAD resin and CLLE (Table I). Confirmation by GC/MS on both SE-30 and bentone-didecyl phthalate columns was made. Apparently, CLLE extraction into CHC13 stopped subsequent hydrolysis of the 1,1,l-trichloroacetone. l,l,l-Trichloroacetone was not found during GC/MS analysis with both SE-30 and bentone-didecyl phthalate columns in an analysis of the river water influent to the Belmont Water Purification Plant. This indicated that this compound is forming in the water treatment process. A blank was run on the CLLE apparatus by substituting prechloroform extracted air for the water sample a t an air: solvent ratio of 15:l. In a 44-1. air blank, diethyl carbonate, carbon tetrachloride, 1,1,2,2-tetrachloroethane,pentachloroethane, hexachloroethane, and a tetrachloropropene isomer were identified as background compounds in the solvent. Only ethyl acetate was identified in the ether utilized from XAD-2 resin extraction. An ether elution before each sampling period did not indicate any l,l,l-trichloroacetone. After the blank 1
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Figure 1. Reconstructed gas chromatogram on SE-30 of Philadelphia drinking water collected by XAD-2 macroreticular resin column 21 6/75 Response is total ion current normalized to ether solvent peak. 1) ether solvent, 2) chloroform, 3) bromodichloromethane,4) dibromochloromethane,5) tetrachloroethylene,6) 1,1,I-trichloropropanone. 7) rn-, pxylene isomers and ethyl benzene (unresolved mixture), 8 ) *xylene, 9) bis(2-chloroethy1)etherand a C3-benzene isomer (unresolvedmixture)
Table 1. Summary of Sampling Information 1975 Sample dales
Flow rate, i./h
216 3/24-25 3/25-26
18 15 15
4/17 4/ 17 b- 19
18 15
8120-21
14
8120-21
1.5
8120-21
15
Total voi , I.
lnllial lap water Conductivity, pmhos
PH PH Delaware River (Torresdale Water Purificatlon Plant) drinking water Free chlorination by XAD-2 resin column 8.3 220 4.1 90 8.5 230 4.0 215 190 8.6 235 4.1 Ammoniationa (began 4/1/75) by XAD-2 resin column 70 8.7 225 4.0 420 8.6 230 3.9 Schuylkill Rlver (Belmont Water Purification Plant) drinking water Ammoniationa by XAD-2 resin column 500 7.2 ... 4.0 Ammoniation by CLLE 88 7.2 ... 7.2 Schuylkill Rlver water Influent to Belmont Water Purification Plant 54 7.7 ... 4.0
Sampling conditions Conductivity, @mhos
260 250 255 260 255
... ... ...
a Dechlorination is not accomplished by Na2S03after ammoniation. Activated Carbon was added to the rapid mix chamber beginning 9:00 a.m., 4/18/75. Sampling began 4/17 at 9:30p.m. Therefore, 33% of the sampling time was not in the presence of carbon, a total aqueous volume of 140 I. This volume is sufficient for identification of trichloroacetone. River water was filtered through loosely packed preextracted glass wool after 4 h setting.
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Figure 2. Mass spectrum Df l , l ,1-trichloroacetone Top: isolated from X A D 2 macroreticularresin column 2/6/75; bottom: reference spectrum from Registry of Mass Spectra (9)
is completed, the column is recleaned before sampling. A true method blank with water was not run because of organics observed in distilled water. Figure 1shows the initial part of a reconstructed gas chromatogram of the first sample (2/6/75) on 20% SE-30. Trichloroacetone is a t scan number 27. This corresponds to an absolute retention time of 4.20 min. The relative retention time to 2-ethyl-1-hexanol (absolute retention time = 9.00 min) is 0.47. Figure 2 (top) shows the mass spectra of l,l,l-trichloroacetone obtained from the GC/MS system. The base peak at m/e 43 contains over 70% of the total ionization. This peak is from the acetyl group. PBM identified l,l,l-trichloroacetone as the best match, with 1,l-dichloroacetone second. The STIRS results for substructure identification showed the following substructures among the top five listed best matches for the overall match factor: C-Cl3 (top two compounds), C=O (four compounds) and C12CC=O (three compounds). These substructures are consistent with l,l,l-trichloroacetone. The spectrum (Figure 2, top) was then compared to the reference spectrum of l,l,l-trichloroacetone in the Registry of Mass Spectral Data (Figure 2, bottom) (10). The spectra of the sample appeared to be grossly different, since the Registry Spectrum showed a base peak at mle 15, and isotopic chlorine peaks were clearly defined (e.g., 97-99-101). This was not true of the spectrum obtained from our GCIMS system which was scanned from mle 30.
Definitive identifications of l,l,l-trichloracetone were completed by direct comparison of GC retention times on the SE-30 and bentone columns and mass spectra from the GC/MS system and the mass spectra of pure reference compound on the same GC/MS system. The use of two independent isolation methods minimizes the likelihood that a compound is altered during sampling and analysis and adds a measure of assurance to the confirmation of a compound. l,l,l-Trichloroacetone was obtained from Aldrich Chem. Co., Madison, Wis. The Torresdale water purification plant began ammoniation as part of the treatment process on 4/1/75 for taste and odor contFol. When ammonia is added to the process, there is a total chlorine residual of 2.2 ppm which contains approximately 2.0 ppm monochloroamine and 0.2 ppm dichloroamine. The change of process from free chlorination to ammoniation did not appear to affect the presence of trichloroacetone. The change of the treatment process to ammoniation did not enable the water sample to be dechlorinated by Na2SO3 before it was passed through the XAD-2 column. This did not appear to affect the recovery of trichloroacetone. Apparently l,l,l-trichloroacetone was stabilized by adjustment to pH 4 during the XAD-2 sampling procedure and by extraction into chloroform by CLLE sampling. This study suggests that l,l,l-trichloroacetone can be forming slowly during the water treatment process and in the water distribution system.
Acknowledgment The authors thank Rohm and Haas Corp., Philadelphia, for the use of their GC/MS system, F. W. McLafferty and his staff, Cornel1University, for complementary use of the initial PBM/STIRS System and his review of that aspect of the manuscript, and Commissioner Carmen F. Guarino, J. V. Radziul, and A. Hess of the Philadelphia Water Department for a review of the manuscript. Literature Cited (1) Rook, J . J., Water Treat. Exam., 23,234 (1974).
(2) Bellar, T. A., Lichtenberg, J. J., Kroner, R. C., J . A m . Water Works Assoc., 66,703 (1974). (3) EPA Interim Report to Congress, “Preliminary Assessment of Suspected Carcinogens in Drinking Water”, EPA, Washington, D.C., June 1975. (4) Morris, J. C., “Formation of Halogenated Organics by Chlorination of Water Supplies”, EPA, EPA-600/1-75-002, March 1975. (5) Bartlett, P. D., J.Am. Chem. Soc., 56,967 (1934). (6) 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., J . Chromatogr., 99,745 (1974). (7) Wu, C., Suffet, I. H., ASTM Special Technical Publication 582, p 90,1975. ( 8 ) McLafferty, F. W., Hertel, R. H., Villwock, R. D., Org. Mass Spectrom., 9,690 (1974). (9) Venkataraghaven, R., Kwok, K.-S., McLafferty, F. W., J . A m . Chem. SOC.,95,4185 (1973). (10) Stenhagen, E., Abrahamsson, S., McLafferty, F. W., “Registry of Mass Spectral Data”, Wiley-Interscience, New York, N.Y., 1974.
Received for review November 25, 1976. Accepted J u n e 17, 1976. Financial support by the Philadelphia Water Department.
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Correct ion In the article, “Evaporation Rates and Reactivities of Methylene Chloride, Chloroform, l,l,l-Trichloroethane, Trichloroethylene, Tetrachloroethylene, and Other Chlorinated Compounds in Dilute Aqueous Solutions” [Enuiron.
Sci. Technol., 9,833-38 (1975)], by W. L. Dilling, N. B. Tefertiller, and G. J. Kallos, on page 835, Table I, the 20th compound should be CH2ClCHClCH2Cl instead of CH2ClCHClCHC12.
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