Tribromoacetic Acid Research Articles

Kinetics of Haloacetic Acid Reactions with Fe(0)

Detailed kinetic studies of the reactions of haloacetic acids (HAAs) with Fe(0) were performed in longitudinally mixed batch reactors. The reactions of tribromoacetic acid (TBAA), bromodichloroacetic acid, and chlorodibromoacetic acid were mass transfer limited, with corrected mass transfer coefficients of 3.7-3.9 x 10(-4) m/s. The reactions of trichloroacetic acid (TCAA), dichloroacetic acid (DCAA), chloroacetic acid (CAA), and bromoacetic acid (BAA) were reaction limited. Bromochloroacetic acid (BCAA) and dibromoacetic acid (DBAA) were partially reaction limited. For the reaction limited species and partially reaction limited species, intra- and interspecies competition effects were observed. A Langmuir-Hinshelwood-Hougen-Watson kinetic model incorporating a mass transfer term was adopted to account for these effects. The lumped kinetic parameters for the HAAs ranged from 0.04 to 248 microM min(-1) for an iron loading of 0.3 g of Fe/125 mL and followed the trend DBAA > BCAA > TCAA > BAA > DCAA. The adsorption parameters ranged from 0.0007 to 0.0065 microM(-1). The effect of dissolved oxygen (DO) on the reaction of TBAA or BAA with Fe(0) was also investigated. No significant effect of DO on the reaction rate of TBAA, which is a mass transfer limited species, was observed. A lag phase, however, was observed for the reaction of BAA, which is a reaction limited species, until the DO was depleted. Simulations were performed to investigate the potential significance of the reactions of HAAs with Fe(0) in water distribution systems.

Degradation of Disinfection Byproducts in Drinking Water

An investigation of the behavior of different categories of disinfection byproducts (DBPs) in ultrapure water and in spiked drinking water samples was performed. The influence of sunlight, pH, and time was examined. Several of the compounds were subject to degradation with time, while others showed increasing trends, possibly due to natural production by bacteria. Chloroform, monochloroacetonitrile, and monochloroacetic acid slightly increased in the presence of sunlight, while d ichloroacetonitrile, dibromoacetic acid, tribromoacetic acid, and mixed bromo-chloro acetic acids were subject to decomposition, especially under sunlight. However, sunlight was found to decelerate decomposition of trichloropropanone and to prevent decomposition of bromochloro-acetonitrile and chloral hydrate. Trichloropropanone decomposed to chloroform, while mixed haloacetic acids decomposed to the corresponding trihalomethanes. Multiple regression equations were obtained for the concentrations of i ndividual DBPs in drinking water as a function of time, pH, and sunlight. Most of the volatile DBPs decreased with increasing pH both in sunlight and in darkness, while haloacetic acids remained unaffected from pH. However, haloacetic acids seemed to be influenced by sunlight to a significantly greater extent than volatile DBPs. Knowledge of the behavior of individual compounds during exposure to sunlight is essential towards the development of photolysis-based removal techniques. pH influence needs to b e considered, especially in the case of volatile DBPs.

Decomposition of trihaloacetic acids and formation of the corresponding trihalomethanes in drinking water

The decomposition of trihaloacetic acids [bromodichloroacetic acid (BDCAA), dibromochloroacetic acid (DBCAA), tribromoacetic acid (TBAA)], and the formation of the corresponding trihalomethanes [bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM)] were studied. Like TBAA, the two mixed chlorobromo-species, BDCAA and DBCAA, were found to decompose to form BDCM and DBCM, respectively, via a decarboxylation pathway. The decomposition of BDCAA, DBCAA and TBAA in water at neutral pH follows a first-order reaction, with rate constants of 0.0011, 0.0062 and 0.040 day −1 at 23°C, respectively; and 0.000028, 0.00014 and 0.0016 day −1 at 4°C, respectively. The activation energies for the decomposition reaction of BDCAA, DBCAA and TBAA in water at neutral pH were found to be 35.0, 34.5 and 29.2 kcal/mol, respectively. The effect of pH in the range of 6–9 and the effect of a drinking water matrix on the decomposition of BDCAA, DBCAA, and TBAA in water were found to be insignificant. Measurement and health implications due to decomposition of trihaloacetic acids and formation of the corresponding trihalomethanes were discussed. By applying the technique of quantitative structure–activity relationships (QSAR), the decomposition rate constants of six iodinated trihaloacetic acids were estimated.

Mammalian cell cytotoxicity and genotoxicity analysis of drinking water disinfection by-products.

Cytotoxicity and genotoxicity assays were used to analyze drinking water disinfection by-products (DBPs) in Chinese hamster ovary (CHO) AS52 cells. The DBPs were chosen because they are common in drinking water, resulting from conventional disinfection using chlorination and chloramination. Data were also available to compare these results with cytotoxicity and mutagenicity studies in Salmonella typhimurium. The rank order in decreasing chronic cytotoxicity measured in a microplate-based assay was bromoacetic acid (BA) >> 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone (MX) > dibromoacetic acid (DBA) > chloroacetic acid (CA) > KBrO(3) > tribromoacetic acid (TBA) > EMS (ethylmethanesulfonate, positive control) > dichloroacetic acid (DCA) > trichloroacetic acid (TCA). The induction of DNA strand breaks by these agents was measured by alkaline single-cell gel electrophoresis (SCGE, comet assay) and the rank order in decreasing genotoxicity was BA >> MX > CA > DBA > TBA > EMS > KBrO(3), while DCA and TCA were refractory. BA was more cytotoxic (31x) and genotoxic (14x) than MX in CHO cells. BA was over 400x more genotoxic than potassium bromate. The brominated haloacetic acids (HAAs) were more cytotoxic and genotoxic than their chlorinated analogs. The HAAs expressed a statistically significant inverse relationship in CHO cell cytotoxicity and genotoxicity as a function of increased numbers of halogen atoms per molecule. A quantitative comparison was conducted with results from a previous study with cytotoxicity and mutagenicity in S. typhimurium. There was no correlation between chronic CHO cell and bacterial cell cytotoxicity. DBP-induced CHO cell cytotoxicity was not related to mutagenic potency in S. typhimurium. Cytotoxicity in CHO cells was statistically significant and highly correlated to CHO cell genotoxicity. Finally, we determined that the DBP genotoxic potency in CHO cells and the mutagenic potency in S. typhimurium were not related. This suggests that toxicity data in S. typhimurium did not quantitatively predict the toxic effects of DBPs in mammalian cell systems. The microplate CHO cell cytotoxicity and genotoxicity assays were well suited for the analysis of DBPs, especially when the quantity of test material is limited.

Comparing TOTAL HAA and TOTAL THM CONCENTRATIONS using ICR data

The US Environmental Protection Agency's Information Collection Rule (ICR) provided a rich source of occurrence data for total trihalomethanes (TTHMs) and six of the nine bromine‐ and chlorine‐containing haloacetic acids (HAAs), i.e., HAA6. A limited number of utilities participating under the ICR measured the remaining three HAAs—bromodichloroacetic acid, dibromochloroacetic acid, and tribromoacetic acid, collectively referred to as HAA3; however, extensive occurrence data for these HAA species are still lacking. An examination of the first 12 months of available ICR disinfection by‐product (DBP) data found that these three HAA species constitute a significant fraction of total HAA (HAA9) concentrations in finished drinking waters. A model was developed to estimate HAA3 occurrence using measured concentrations of trichloroacetic acid and individual TTHM species. The model estimated HAA3 concentrations reasonably well, and after estimated HAA3 concentrations were added to ICR HAA6 results, the model allowed for generation of a national distribution of total HAA occurrence. The median HAA9 level for this national distribution was approximately equal to the observed median ICR TTHM concentration. This finding suggests that THM/HAA relationships in US drinking waters need to be reevaluated with respect to DBP exposure and regulation.

Reduction of haloacetic acids by Fe0: implications for treatment and fate.

To predict the fate of haloacetic acids (HAAs) in natural or engineered systems, information is needed concerning the types of reactions that these compounds undergo, the rates of those reactions, and the products that are formed. Given that many drinking water distribution systems consist of unlined cast iron pipe, reactions of HAAs with elemental iron (Fe0) may play a role in determining the fate of HAAs in these systems. In addition, zerovalent iron may prove to be an effective treatment technology for the removal of HAAs from chlorinated drinking water and wastewater. Thus, batch experiments were used to investigate reactions of four trihaloacetic acids, trichloroacetic acid (TCAA), tribromoacetic acid (TBAA), chlorodibromoacetic acid (CDBAA), and bromodichloroacetic acid (BDCAA), with Fe0. All compounds readily reacted with Fe0, and investigation of product formation and subsequent disappearance revealed that the reactions proceeded via sequential hydrogenolysis. Bromine was preferentially removed over chlorine, and TBAA was the only compound completely dehalogenated to acetic acid. In compounds containing chlorine, the final product of reactions with Fe0 was monochloroacetic acid. Halogen mass balances were 95-112%, and carbon mass balances were 62.6-112%. The pseudo-first-order rate constants for trihaloacetic acid degradation were as follows: BDCAA (10.6 +/- 3.1 h-1) > CDBAA (1.43 +/- 0.32 h-1) approximately TBAA (1.41 +/- 0.28 h-1) >> TCAA (0.08 +/- 0.02 h-1).

Metabolism, microflora effects, and genotoxicity in haloacetic acid-treated cultures of rat cecal microbiota.

Haloacetic acids are by-products of drinking water disinfection. Several compounds in this class are genotoxic and have been identified as rodent hepatocarcinogens. Enzymes produced by the normal intestinal bacteria can transform some promutagens and procarcinogens to their biologically active forms. The present study was designed to investigate the influence of the cecal microbiota on the mutagenicity of haloacetic acids, and to look at changes in the microbiota populations and enzyme activities associated with exposure to haloacetic acids. PYG medium containing 1 mg/ml of monochloroacetic (MCA), monobromoacetic (MBA), dichloroacetic (DCA), dibromoacetic (DBA), trichloroacetic (TCA), tribromoacetic (TBA), or bromochloroacetic (BCA) acid was inoculated with rat cecal homogenate and incubated anaerobically at 37 degrees C. Growth curves were performed with enumeration of the microflora populations on selective media. Mutagenicity in a Salmonella microsuspension bioassay was determined after incubation for various lengths of time, with or without the cecal microbiota. At 15 h of incubation, enzyme assays determined the activities for beta-glucuronidase, beta-galactosidase, beta-glucosidase, azoreductase, nitroreductase, dechlorinase, and dehydrochlorinase. The haloacetic acids, with the exception of BCA, were toxic to the cecal microbiota, and especially to the enterococci. DBA, TBA, and BCA were mutagenic in the microsuspension assay, but the presence of the intestinal flora did not significantly alter the mutagenicity. BCA increased the activities of several enzymes, and therefore has the potential to affect the biotransformation of co-exposed compounds.

THM, haloacetic acids and other organic DBPs formation in disinfection of bromide rich Sea of Galilee (Lake Kinneret) water

Lake Kinneret (Sea of Galilee) is the main freshwater body in Israel and is the water source for the National Water Carrier (NWC). The lake water has a uniquely high bromide content 1.9 mg/L which affects DBPs (disinfection by-products) formation. Controlled experiments using different disinfectants were carried out with the lake water in order to study DBPs formation. Formation and distribution of TOX (total organic halogen) trihalomethanes (THM), haloacetic acids (HAA) and cyanogen halides were studied during the application of the following disinfectants: Chlorine, chloramine, chlorine dioxide and a combination of chlorine dioxide with chloramine. Brominated species dominated the distribution of THM, HAA and cyanogen halide. When a high dose of chlorine was applied an unusually high percent (75%) of the TOX formation potential was identified; THM constituted about 50% of the TOX formation potential and haloacetic acids 22-28%. Tribromoacetic acid was found to undergo decomposition to form bromoform. Chlorine dioxide produced insignificant concentrations of organic DBPs and chloramine produced low concentrations. Chlorine dioxide in combination with chloramine enhanced production of CNBr and THM, but their concentrations were much lower than during chlorination.

Analytical methods for water disinfection byproducts in foods and beverages

The determination of exposure to drinking water disinfection byproducts (DBPs) requires an understanding of how drinking water comes into contact with human through multiple pathways. In order to facilitate the investigation of human exposure to DBPs via foods and beverages, analytical method development efforts were initiated for haloacetonitriles, haloketones, chloropicrin, and the haloacetic acids (HAAs) in these matrices. The recoveries of the target analytes were investigated from composite foods and beverages. Individual foods and beverages used to investigate the general applicability of the developed methods were selected for testing based on their watercontent and frequency of consumption. The haloacetonitriles, the haloketones, and chloral hydrate were generally well recovered (70-130%), except for bromochloroacetonitrile (64%) and dibromoacetonitrile (55%), from foods spiked after homogenization and following extraction with methyl-t-butyl ether (MTBE); the addition of acetone was found to be necessary to improve recoveries from beverages. The process of homogenization resulted in decreased recoveries for the more volatile analytes despite the presence of dry ice. The HAAs were generally well recovered (70-130%), except for trichloroacetic acid (58%) and tribromoacetic acid (132%), from foods but low recoveries and emulsion formation were experienced with some beverages. With both groups of analytes, certain matrices were more problematic (as measured by volatility losses, emulsion formation) than others with regard to processing and analyte recovery.

Development of quantitative comparative cytotoxicity and genotoxicity assays for environmental hazardous chemicals

Mammalian cell asays can provide toxicological information that may be more relevant to human risk asessment than commonly used microbial tests. Rapid, semi-automated, quantitative mammalian cell cytotoxicity and genotoxicity assays were developed to analyze drinking water disinfection by-products (DBPs). These assays employ 96-well microplates; selected DBPs were analyzed with cultured Chinese hamster ovary (CHO) cells. The concentration of the DBPs that repressed 50% of CHO cell growth with a 72 h exposure was calculated as the %C1/2 value. Using these values the rank order (from highest to lowest cytotoxicity) was bromonitromethane, dibromonitromethane, tribromonitromethane, bromoacetic acid, dibromoacetic acid, and tribromoacetic acid. Genotoxicity analyses of the DBPs were conducted using the single cell gel electrophoresis (SCGE) assay. This assay detects genomic DNA damage at the level of the individual nucleus. Using SCGE genotoxic potency the rank order was bromoacetic acid> dibromonitromethane>>bromonitromethane>dibromoacetic acid>tribromoacetic acid. The relative cytotoxicity and genotoxicity of these agents were compared with Salmonella typhimurium. Studies of specific DBPs in mammalian cell systems are important to compare the toxicity of these hazardous water contaminants. Such knowledge is necessary for risk assessment and to assist in the formulation of public regulatory policies that protect the environment and the public health.

Determination of Haloacetic Acids in Water by Ion Chromatography—Method Development

The microextraction/ion chromatographic (IC) method developed in this study involves extraction of 9 haloacetic acids (HAAs) from aqueous samples (acidified with sulfuric acid to a pH of < 0.5 and amended with copper sulfate pentahydrate and sodium sulfate) with methyl tert-butyl ether (MTBE), back extraction into reagent water, and analysis by IC with conductivity detection. The separation column consists of an Ion Pac AG-11 (2 mm id x 50 mm length) guard column and an Ion Pac AS-11 (2 mm id x 250 mm length) analytical column, and the concentration column is a 4 mm id x 35 mm length Dionex TAC-LP column. Use of the 2 mm id Dionex AS-11 column improved detection limits especially for trichloracetic acid (TCAA), bromodichloroacetic acid (BDCAA), dibromochloroacetic acid (DBCAA), and tribromoacetic acid (TBAA). The peak interfering with BCAA elutes at the same retention time as nitrate; however, we have not confirmed the presence of nitrate. Stability studies indicate that HAAs are stable in water for at least 8 days when preserved with ammonium chloride at 100 mg/L and stored at 4 degrees C in the dark. At day 30, recoveries were still high (e.g., 92.1-106%) for dichloroacetic acid (DCAA), BCAA, dibromoacetic acid (DBAA), trichloroacetic acid (TCAA), BDCAA, and DBCAA. However, recoveries of monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), and TBAA were only 54.6, 56.8, and 66.8%, respectively. Stability studies of HAAs in H2SO4-saturated MTBE indicate that all compounds except TBAA are stable for 48 h when stored at 4 degrees C in the dark. TBAA recoveries dropped to 47.1% after 6 h of storage and no TBAA was detected after 48 h of storage. The method described here is only preliminary and was tested in only one laboratory. Additional research is needed to improve method performance.

Analysis of haloacetic acid mixtures by HPLC using an electrochemical detector coated with a surfactant-nafion film

High pressure liquid chromatography (HPLC) using an electrochemical (EC) detector electrode of pyrolytic graphite coated with a film of ionomer Nafion and the water-insoluble surfactant didodecyldimethylammonium bromide (DDAB) was used to achieve separation and detection of all six bromo- and chloro-acetic acids. The Nafion-DDAB film preconcentrates the acid anions facilitating their electrochemical detection by direct reduction at −1.2 V versus SCE. Detection limits were poorer than the EPA-approved GC-ECD method, but HPLC-EC avoids the derivatization necessary for GC. The HPLC-EC method also detected tribromoacetic acid, which has not been determined simultaneously with other halogenated acids by reported chromatographic methods. The HPLC-EC method using a Nafion-DDAB-coated detector electrode gave comparable results to GC-ECD for the determination of TCA in drinking water.

Effect of Bromide Ion on Haloacetic Acid Formation during Chlorination of Biscayne Aquifer Water

Water drawn from the Biscayne Aquifer, an extensively used potable water supply source in Florida, was used to study the effect of the bromide ion on haloacetic acid (HAA) formation during chlorination. The source water contained an ambient bromide ion concentration (160 μg/L) and a substantial concentration of natural organic matter (nonpurgeable organic carbon = 10.9 mg/L). A systematic evaluation, encompassing a range of bromide ion concentration spikes, and reaction times at fixed pH, chlorine dose, and temperature conditions, was conducted. Two chlorinated HAAs (dichloroacetic acid and trichloroacetic acid), two brominated HAAs (dibromoacetic acid and tribromoacetic acid), and three mixed HAAs (bromochloroacetic acid, bromodichloroacetic acid, and dibromochloroacetic acid) were found. Monobromoacetic acid and monochloroacetic acid were below detection limits in all of the chlorinated samples. In contrast to the findings of previous studies, the molar yield of HAAs increased as the initial bromide ion...

Determination of Haloacetic Acids from Aqueous Samples Collected from the Canadian Environment Using an In Situ Derivatization Technique

Abstract Determination of haloacetic acid concentrations in Canadian environmental samples were carried out using an in situ derivatization method. An existing method used to quantitate monochloroacetic acid was extended to analyze simultaneously for 2,4-difluoroanilide of fluoro-, chloro- and bromoacetic acids in aqueous samples. This method requires reduction of sample volume to 50 mL, and then reacting the concentrate with 2,4-difluoroaniline using dicyclohexyl-carboiimide as catalyst in ethyl acetate to produce the acid anilide. Quantitation utilizes gas chromatography with mass selective detector in the selected ion monitoring mode. The response at m/z 129 was used to quantitate the mono-substituted acids and, with the exception of trifluoroacetic acid, the di- and tri-substituted acids were quantitated using m/z 156. Quantitation of trifluoroacetic acid utilized m/z 225. The ubiquitous nature of these compounds required analyzing a blank with each sample as traces of the haloacids were found in the solvent and chemicals used in the method. All nine anilides were synthesized with the response from standard solutions used for quantitation. Environmental samples from 14 locations were analyzed and these included lake water (replicates), rain, snow, groundwater and drinking water samples. With the exception of one groundwater sample, mono- and dichloroacetic acids were found in all samples at concentrations in the range of 0.02 to 8 µg/L. Also mono- and trifluoroacetic acid were found in 9 of 14 and 7 of 14 of the samples, respectively (0.004 to 0.600 µg/L). Monobromoacetic acid was found mainly in the drinking water samples at 4 µg/L. The dibromoacetic acid was detected in snow and drinking water samples, and trichloro- and difluoroacetic acids were detected in only a few samples. Tribromoacetic acid was not detected in any of the samples.

Formation and Degradation of Halogenated Organic Acids. Radiation versus Photocatalytically Induced Processes

AbstractRadiation chemistry and photocatalysis are introduced as complementary methods for the study of the radical- and redox-induced degradation of organic substrates. Particular focus is devoted on the reductive and oxidative formation and destruction of halogenated organic acids, as intermediates in the degradation of halo- genated hydrocarbons, in dilute aqueous solutions. The specific aim of this comparative essay is to point out the fundamental similarities between a radiation chemical and photocatalytical approach but, at the same time, to demonstrate that and why significant differences may, nevertheless, be observed. The examples presented and discussed are concerned with (i) the oxidatively and reductively induced degradation of 1,1,1-trichloroethane to organic acids, (ii) corresponding experiments on the degradation of trifluoro-, trichloro- and tribromoacetic acid, (iii) peculiarities of the degradation processes in the absence of oxygen, and (iv) the importance of the cross­termination reaction between halogenated peroxyl radicals and superoxide, O

Haloalkanoate dehalogenase II (DehE) of a Rhizobium sp.--molecular analysis of the gene and formation of carbon monoxide from trihaloacetate by the enzyme.

A 3-kb EcoRI fragment of genomic DNA from a Rhizobium sp. cloned into pUC19 endowed Escherichia coli K-12 with the ability to grow, albeit slowly, with 2-chloropropionic acid as substrate. The construct expressed weakly a gene that encoded a non-stereospecific 2-chloropropionic acid dehalogenase (dehalogenase II; DehE). The dehE gene was not closely linked to the organism's other two dehalogenase genes, dehD and dehL. The derived amino acid sequence of DehE showed little identity with DehD or DehL, but there was significant identity to two other dehalogenases that act non-selectively on 2-chloropropionic acid. The fragment carried a truncated ORF upstream of dehE that was 51% identical to a positively acting regulatory protein, DehR, required for expression of a Pseudomonas putida dehalogenase gene. In its complete form this gene could encode the Rhizobium sp. dehalogenase-regulatory protein. DehE dehalogenated tribromoacetic acid completely, forming stoichiometric amounts of carbon monoxide and carbon dioxide as the other products.

Research Associated with the Development of EPA Method 552.2

The work presented in this paper entails the development of a method for haloacetic acid (HAA) analysis, Environmental Protection Agency (EPA) method 552.2, that improves the safety and efficiency of previous methods and incorporates three additional trihalogenated acetic acids: bromodichloroacetic acid, chlorodibromoacetic acid, and tribromoacetic acid, which are not included in the previous two methods, standard method 6251B and EPA method 552.1. The final procedure includes a microextraction coupled with derivatization by acidic methanol. All nine possible brominated and chlorinated HAAs are detectable at concentrations of less than 1 pg/L. The objective of this paper is to describe the various approaches that were explored, the conclusions that were drawn from the associated studies, and the reasoning behind the changes that were incorporated into EPA method 552.2

Determination of Bromate in the Presence of Brominated Haloacetic Acids by Ion Chromatography with Inductively Coupled Plasma Mass Spectrometric Detection

Bromate is a disinfection by product (DBP) in drinking water that is formed during the ozonation of a source water containing bromide. Brominated haloacetic acids are DBPs that are anions at near-neutral pHs. The anion character of bromoacetic acid (pKa = 2.7) is similar to bromate, which causes the two species to coelute when NaOH is used as an eluent. Four columns are evaluated as a means of removing the potential false positives generated by bromoacetic acid. The alkyl quaternary amine based PA-100 guard column separates bromate from bromoacetic acid using 100 mM NaOH, but the analysis time is greater than 12 min. The use of 5 mM HNO3 as an eluent (with the PA-100) provides adequate separation of bromate from bromoacetic acid with an analysis time of less than 8 min. The stability of bromate in 5 mM HNO3 was evaluated using a DDI matrix (pH adjusted to 5.5, fortified with bromide) and a drinking water matrix (pH 4−9). The bromate recoveries in these two matrices were 93−105% with less than 4% RSDs. Tribromoacetic acid produces a broad peak that envelops the retention window of bromate. The tribromoacetic acid was removed using a reverse-phase sample pretreatment cartridge. The overall analysis procedure was evaluated in a synthetic chloride, sulfate, and nitrate matrix. In addition, precision and recovery data were collected from five ozonated drinking waters. The percent recoveries in the ozonated waters ranged from 90 to 98% with RSDs of less than 6%. The method detection limit for bromate is 0.8 μg/L.

Radical-mediated degradation mechanisms of tribromo- and other trihalogenated acetic acids in oxygen-free solutions as studied by radiation chemistry methods

R. Fliount, O. Makogon, D. M. Guldi and K. Asmus, J. Chem. Soc., Perkin Trans. 2, 1997, 1535 DOI: 10.1039/A700240H

Determination of halogenated acetic acids in chlorinated sea water and drinking water produced offshore

The formation of halogenated acetic acids in laboratory chlorinated sea water as well as chlorinated sea water and drinking water produced on an oil-installation offshore was investigated. Analyses were performed using solvent extraction and capillary gas chromatography with electron capture detection and mass spectrometry. Dichloroacetic acid, trichloroacetic acid, dibromoacetic acid and tribromoacetic acid were found in the water samples, with dibromoacetic acid present in the highest concentration (1–6 μg/l). When quenching agents were applied to remove excessive halogen prior to extraction, significantly different concentrations of dibromoacetic acid were observed when samples were quenched with sodium thiosulfate or ammonium sulfate. Sodium thiosulfate quenched samples contained the lowest concentration of dibromoacetic acid and other unidentified products. A stability experiment showed that the presence of sodium thiosulfate did not affect the concentration of dibromoacetic acid in aqueous solutions. The increased levels of dibromoacetic acid in unquenched and ammonium sulfate treated samples is explained by an extended reaction of excessive halogen with organic material in the acid water samples during the time needed for extraction.