ANALYST, JANUARY 1993, VOL. 118 50 71 [M - Br - COl+ 281 - \ 173 0.11 ' I I I 1 Ill I Identification of Trihaloacetaldehydes in Ozonated and Chlorinated Fulvic Acid Solutions Yuefeng Xie and David A. Reckhow Environmental Engineering Program, Department of Civil Engineering, University of Massachusetts, Amherst, MA 01003, USA Three brominated trihaloacetaldehydes (THAs), bromodichloroacetaldehyde, dibromochloroacetaldehyde and tribromoacetaldehyde, were identified, by gas chromatography-mass spectrometry, in ozonated and chlorinated aqueous fulvic acid solutions containing inorganic bromide. Mass spectra of these THAs were obtained in the electron-impact and positive chemical-ionization modes. The significance of the formation of brominated THAs on water quality and future disinfection by-product regulation is discussed.Keywords: Mass spectra; chlorination; ozonation; disinfection by-products; trihaloacetaldeh ydes Since brominated trihalomethanes (THMs) were first re- ported in the 1970~~1 a number of other brominated disinfec- tion by-products (DBPs) have been found in chlorinated drinking waters high in inorganic bromide.2.3 Owing to the widespread occurrence of bromide in raw waters and signifi- cant health effects associated with bromine substitution, the US Environmental Protection Agency (EPA) is likely to establish strict maximum contamination levels (MCLs) for some of these compounds4 in the coming disinfectants and disinfection by-products (D-DBP) rule. Trichloroacetaldehyde (chloral hydrate) was first reported in chlorinated waters by Uden and Miller.5 Since then several studies have been conducted to investigate the formation and toxicity of chloral hydrate in drinking water.2.6 Because of the carcinogenic properties of chloral hydrate, the US EPA is currently considering the establishment of an MCL in the new D-DBP rule.4 As with the brominated THMs, brominated trihaloacetaldehydes (THAs) can be formed in chlorinated waters high in inorganic bromide.However, the formation of brominated THAs in chlorinated water has not been investi- gated. The objective of the present study was to investigate the presence of brominated THAs in chlorinated and ozonated aqueous fulvic acid solutions containing bromide, and to characterize their mass spectra. Experimental Sample Preparation Solutions of fulvic acid were prepared from a stock concen- trated fulvic acid extract7 (from Thousand Acre reservoir, Athol, MA, USA) with Super-Q water (Millipore, Bedford, MA, USA) to yield a dissolved organic carbon (DOC) concentration of 4 mg 1-1.Following the addition of potassium bromide (0.5, 1.5 and 4 mg I-* as bromide), the aqueous ozone was applied to the fulvic acid solution, buffered at pH 7 with phosphate, at a dose ratio of ozone to DOC of 1 mg mg-1. After storing the ozonated samples in the dark at 20 "C for 3 h, chlorine (in the form of NaOCI) was added to samples containing 0.5 and 1.5 mg 1-1 bromide at a concentration of 20 mg 1-1, and samples were set to react for 24 h in the dark at 20 "C. A 500 ml ozonated or chlorinated sample was extracted with 2 X 50 ml of methyl tert-butyl ether (MtBE).Before injection, the combined MtBE extracts were concentrated to 10-50 yl in a slow nitrogen flow at 45 "C. GC-MS Analysis Gas chromatography-mass spectrometry (GC-MS) analyses were performed on an HP5899 gas chromatograph coupled with an HP5988 quadrupole mass spectrometer (Hewlett- Packard, Avondale, PA, USA). Extracts were introduced by splitless injection and separated on a PTE-5 capillary column (30 m x 0.32 mm i.d., 0.25 pm film thickness, Supelco, Bellefonte, PA, USA). Helium was used as the carrier gas at a flow rate of 30 cm s-1. The oven temperature was kept at 30 "C for 10 min, then ramped to 200 "C at a rate of 25 "C min-1 and kept at 200 "C for 5 min. The injector temperature was 200 "C and the transfer line was kept at 280 "C.The mass spectrometer was tuned immediately before analysis, with use of perfluorotributylamine as the calibrating compound (mlz 69, 219 and 502). In the electron-impact (EI) mode, the ion-source temperature was 200 "C, the election energy was 70 eV, and the mass scan range was 30-400 u. In the positive chemical-ionization (PCI) mode, the ion-source temperature was 100 "C, the electron energy was 240 eV, and the mass scan range was 100-400 u. Methane was used as the reagent gas for PCI. Results and Discussion Identification of Brominated Trihaloacetaldehydes Mass spectra for major constituents in the extracts from ozonated fulvic acid solutions were obtained in the EI and PCI 1 (a) Cluster A loo t II .- [M - Brl+ [M + HI+ 100 150 200 250 300 mlz Fig.1 Mass spectra of tribromoacetaldeh de in ozonated fulvic acid solution ( H = 7, DOC = 4 mg I - l , [Br-i = 4 mg I-', O3 dose = 4 mg 1 - 1 ) . 6) In El mode. ( b ) in PCI mode72 ANALYST, JANUARY 1993, VOL. 118 Table 1 Proposed fragment clusters ion assignments for tribromoacetaldehyde Sub-cluster A1 A2 B1 B2 (170 : 172 : 174) (171 : 173 : 175) (249 : 251 : 253 : 255) (250 : 252 : 254 : 256) Fragments [ M-Br-CHO] + [ M-Br-CO] + [ M-CHO] + [M-CO] + Isotope ratios- Observed 51:100:52 50 : 100 : 50 32 : 100: 102 : 38 34 : 200 : 104 : 34 Theoretical" 51 : 100 : 49 51 : 100 : 49 34: 100:97:32 34: 100:97:32 * Theoretical isotope ratio, calculated by using 7"Br:SlBr (50.69 : 49.31)." Two Br atoms in cluster A and three Br atoms in cluster B. modes to acquire information on both structure and relative molecular mass.One mass spectrum resembling that of bromoform and tribromoacetic acid methyl ester8 was obtained at a retention time (tR) of 13.0 min and this is reproduced in Fig. 1. On careful inspection it appears that cluster A of 170 : 171 : 172 : 173 : 174 : 175 is composed of two clusters, viz., 170 : 172 : 174 and 171 : 173 : 175. Based on the relative abundances, both clusters appear to contain two bromine atoms, as shown in Table 1. The cluster of 249 : 250 : 251 : 252 : 253 : 254 : 255 : 256 also comprised two similar clusters. Each of these apparently contains three bromine atoms. Based on the PCI mass spectra, the relative molecular mass of this compound is 278. After logical assignment of fragments this mass spectrum was concluded to be that of tribromoacetaldehyde.Therefore, the four sub-clusters result from the following losses from the present molecule: [M-CO]+, [M-CHO]+, [M-Br-CO]+ and [M-Br-CHO]+, as shown in Table 1. The experimentally determined isotope ratio matches the theoretical ratio fairly well. Small differences could be partly due to 13C in the apposing sub-cluster, which is not considered in calculating the theoretical isotope ratios. Three additional EI mass spectra resembling THMs and trihaloacetic acid methyl esters8 were obtained in pre-ozo- nated fulvic acid solutions following chlorination. Based on relative molecular masses determined from the PCI mass spectra and structural information provided by El mass spectra, they were identified as bromodichloroacetaldehyde (tR = 5.1 min), dibromochloroacetaldehyde (tK = 10.8 min) and trichloroacetaldehyde (tR = 2.6 min).Similar double clusters were found in these EI mass spectra. For bromodi- chloroacetaldehyde and dibromochloroacetaldehyde, these clusters were attributed to [M-CO]+ and [M-CHO]+, [M-Br- CO]+ and [M-Br-CHO]+. All THAs except bromodichlo- roacetaldehyde were confirmed by comparison of tK and mass spectra with those of commercial or synthesized chemicals. Significance of THAs in Finished Drinking Water There is limited information available on the toxicity of brominated THAs and the effect of THAs on general water quality. Owing to the carcinogenicity of trichloracetal- dehyde,6 brominated THAs are of potential human health concern.In the anticipated D-DBP rule, trichloroacetal- dehyde is likely to be regulated in finished waters. Formation of brominated THAs in water high in bromide is also likely to result in lower concentrations of trichloroacetaldehyde. This is based on similar effects reported for brominated THMs,' haloacetic acids*() and cyanogen halide.3 Future Research Studies are underway in this laboratory aimed at ( a ) synthesiz- ing bromodichloroacetaldehyde, (b) developing a GC-based method to determine the four THAs in drinking waters, and ( c ) investigating the effects of pH, pre-ozonation and bromide concentration on the formation of THAs. Pilot-scale studies are also planned to investigate the formation and removal of THAs during water treatment. Conclusions Three brominated THAs were identified in ozonated and chlorinated fulvic acid solutions containing inorganic bro- mide.Mass spectra of the THAs are similar to those of the THMs and trihaloacetic acid methyl esters, except for the unique double clusters in the mass spectra of THAs. The authors thank the US National Science Foundation and Dr. Edward H . Bryan for the financial support of this research under grant number BCS-8958392. Thanks also go to the Hewlett-Packard company for their generous financial assis- tance. References 1 2 3 4 5 6 7 8 9 10 Rook, J . J . , Gras, A. A.. van der Hcijdcn, B. G., and de Wee, J., J. Environ. Sci. Health, 1978, A13, 91. Krasncr, S. W., McGuire, M., Jacangclo, J. C., Patania. N. L.. Reagan, K. M., and Aieta. M., J. Am. Water Works Assoc., 1989, 81, 41. Xie, Y . , and Reckhow, D. A.. Water Res., in the press. US EPA, Status Report on Development of Regulations for Disinfectants and Disinfection By-products. US Environmental Protection Agency, Washington, DC, 1991. Uden, P. C., and Miller. J . W., J . Am. Wuter Works Assoc., 1983, 75, 524. Daniel, F. B . , DeAngelo, A. B.. Stober, J. A., and Page, N. P., Fundam. Appl. Toxicol., 1992, 19, 159. Thurman, E. M., and Malcolm, R. L . , Environ. Sci. Technof., 1981, 15, 463. Xie, Y., Rajan, R. V.. and Reckhow, D. A., Org. Mass Spectrom., 1992. 27, 807. CRC Handbook of Chemistry and Physics,ed. Lide. D. R., CRC Press, Boca Raton, FL, 71st edn., 1991. Pourmoghaddas, H.. Doctoral Dissertation, IJniversity of Cincinnati, OH, 1990. Paper 2102458F Received May 12, 1992 Accepted September 24, I992