Anal. Chem. 2009, 81, 4645–4677
Water Analysis: Emerging Contaminants and Current Issues Susan D. Richardson National Exposure Research Laboratory, U.S. Environmental Protection Agency, Athens, Georgia 30605 Review Contents Background Major Analysis Trends Sampling and Extraction Trends Chromatography Trends Online Analysis Emerging Contaminants General Reviews New Regulations/Regulatory Methods New U.S. Drinking Water Regulations The Stage 2 Disinfectants (D)/DBP Rule The Second Unregulated Contaminants Monitoring Rule (UCMR-2) Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) Ground Water Rule Contaminant Candidate List (CCL) New Regulatory Methods for Drinking Water EPA Method 537: Perfluorinated Chemicals EPA Method 522: Dioxane EPA Method 314.2: Perchlorate New Regulatory Methods for Wastewater EPA Method 1694: Pharmaceuticals and Personal Care Products EPA Method 1698: Steroids and Hormones New Developments for Wastewater Sucralose Antimony Nanomaterials PFOA, PFOS, and Other Perfluorinated Compounds Pharmaceuticals, Hormones, and Endocrine Disrupting Compounds Pharmaceuticals Review Articles Illicit Drugs Iodinated X-ray Contrast Media Occurrence Studies of Other Pharmaceuticals Fate and Transport Studies Other Treatment Studies New Methods Endocrine Disrupting Compounds and Hormones Hormones Other EDCs Drinking Water and Swimming Pool Disinfection Byproducts Drinking Water DBPs Combining Chemistry with Toxicology Nitrosamines New Methods DBP Formation Studies Model Compound Studies Occurrence Studies New Swimming Pool Research DBPs of Pollutants Sunscreens/UV Filters Brominated Flame Retardants Benzotriazoles Dioxane
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Siloxanes Naphthenic Acids Musks Pesticide Degradation Products and New Pesticides Reviews Occurrence and Fate Studies Perchlorate Algal Toxins Microorganisms Contaminants on the Horizon: Melamine-Cyanuric Acid Literature Cited
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10.1021/ac9008012 Not subject to U.S. Copyright. Publ. 2009 Am. Chem. Soc. Published on Web 05/20/2009
BACKGROUND This biennial review covers developments in water analysis for emerging environmental contaminants over the period of 2007-2008. A few significant references that appeared between January and February 2009 are also included. Analytical Chemistry’s current policy is to limit reviews to a maximum of 250 significant references and to mainly focus on new trends. Even with a more narrow focus, only a small fraction of the quality research publications could be discussed. This was especially true this year with all the growth in the pharmaceutical area, where my entire allotment of 250 references could have been used in this one section alone. As a result, as with the previous review on water analysis in 2007 (1), this review will not be comprehensive but will highlight new areas and discuss representative papers in the areas of focus. I write a similar review article on environmental mass spectrometry, which also focuses on emerging contaminants (2). That review article is somewhat different from this one, in that it focuses on mass spectrometry methods and applications, and includes measurements of air, soil/sediments, and biological samples, in addition to water. This review on water analysis focuses only on water measurements and applications but includes other methodologies besides mass spectrometry. I welcome any comments you have on this review (
[email protected]). Numerous abstracts were consulted before choosing the best representative ones to present here. Abstract searches were carried out using Web of Science, and in many cases, full articles were obtained. A table of acronyms is provided (Table 1) as a quick reference to the acronyms of analytical techniques and other terms discussed in this review. A table of useful Web sites is also provided (Table 2). Major Analysis Trends. One of the hottest trends the last 2 years has been the use of liquid chromatography (LC) with full scan and high-resolution mass spectrometry (MS) to identify unknown contaminants (often degradation or reaction products of the parent contaminant) or to provide further selectivity for known analytes. Full scan and high-resolution mass spectrometry Analytical Chemistry, Vol. 81, No. 12, June 15, 2009
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Table 1. List of Acronyms APCI APPI BH BM-DBM BP-3 CCL DBPs DHB DHMB E1 E2 E3 EE2 ECD EDCs EI ELISA EPA ESA ESI FAIMS FT FTOHs GC HAAs HBP HILIC HMB IC ICM ICR ICP LC MALDI 4-MBC MCL MDL MF MIMS MRM MS MX NCI NDEA NDMA N-EtPFOSA NMEA NMor NPYR NMR NOM OC ODPABA PBSA PCBs PBDEs PFCs PFBS PFCAs PFDA PFHxA PFHpA PFHS PFNA PFOA PFOS PFOSA PFUnDA SPE SPME THB THMs TOF TOX UCMR-2 USGS UPLC 4646
atmospheric pressure chemical ionization atmospheric pressure photoionization benzhydrol butyl methoxydibenzoylmethane benzophenone-3 contaminant candidate list disinfection byproducts dihydroxybenzophenone 2,2′-dihydroxy-4-methoxybenzophenone estrone 17β-estradiol estriol 17R-ethinylestradiol electron capture detection endocrine disrupting compounds electron ionization enzyme-linked immunosorbent assay Environmental Protection Agency ethane sulfonic acid electrospray ionization high-field asymmetric waveform ion mobility spectrometry Fourier-transform fluorinated telomer alcohols gas chromatography haloacetic acids 4-hydroxybenzophenone hydrophilic interaction chromatography 2-hydroxy-4-methoxylbenzophenone ion chromatography iodinated X-ray contrast media ion cyclotron resonance inductively coupled plasma liquid chromatography matrix-assisted laser desorption ionization 4-methylbenzylidene camphor maximum contaminant level method detection limit microfiltration membrane introduction mass spectrometry multiple reaction monitoring mass spectrometry 3-chloro-(4-dichloromethyl)-5-hydroxy-2(5H)-furanone negative chemical ionization N-nitrosodiethylamine N-nitrosodimethylamine N-ethylperfluorooctane sulfonamide N-nitrosomethylethylamine N-nitrosomorpholine N-nitrosopyrrolidine nuclear magnetic resonance natural organic matter octocrylene octyl-dimethyl-p-aminobenzoic acid phenylbenzimidazole sulfonic acid polychlorinated biphenyls polybrominated diphenyl ethers perfluorinated compounds perfluorobutanesulfonate perfluorocarboxylic acids perfluorodecanoic acid perfluorohexanoic acid perfluoroheptanoic acid perfluorohexanesulfonate perfluorononanoic acid perfluorooctanoic acid perfluorooctane sulfonate perfluorooctane sulfonamide perfluoroundecanoic acid solid phase extraction solid phase microextraction trihydroxybenzophenone trihalomethanes time-of-flight total organic halogen the Second Unregulated Contaminants Monitoring Rule U.S. Geological Survey ultraperformance liquid chromatography
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Table 2. Useful Websites Web site
comments
www.epa.gov
U.S. EPA’s Web site; provides a searchable link to U.S. EPA www.epa.gov/safewater/methods/ U.S. EPA approved methods for analyticalmethods.html drinking water compliance monitoring www.epa.gov/safewater/ucmr/ucmr2/ U.S. EPA Methods approved for methods.html UCMR-2 www.epa.gov/microbes/ordmeth.htm drinking water methods developed by U.S. EPA’s Office of Research and Development www.standardmethods.org link to Standard Methods Online www.astm.org link to ASTM International methods http://infotrek.er.usgs.gov/pubs link to USGS methods
have been used with gas chromatography (GC) in a similar fashion for decades, enabling the identification of many environmental contaminants. With recent instrumental development for LC/mass spectrometers, especially time-of-flight (TOF) (3-5), this full scan and high-resolution/accurate mass benefit is now being utilized both for target analytes but also for identifying nontarget analytes that are highly polar, nonvolatile, or high molecular weight and are not amenable to GC. As a result, within a single analytical run, both targeted and nontargeted analytes can be analyzed or identified without having to carry out additional analyses. In comparison to traditional quadrupole mass spectrometers, which operate at unit resolution and are generally operated in the selected ion monitoring (SIM), selected reaction monitoring (SRM), or multiple reaction monitoring (MRM) modes for specific target analytes, TOF-mass spectrometers are capable of acquiring full-scan mass spectra at high resolution for all analytes without loss in sensitivity. Because most TOF mass spectrometers have a resolution of at least 10 000 at full-width-half-maxima (fwhm) peak height, isotopic patterns are evident and empirical formulas and chemical structures can be proposed for unknowns or confirmed for targeted analytes. This also makes it possible to use mass spectral libraries (5) and to also enable the data file to be reinterrogated months later to find additional unknown contaminants. In addition to TOF-mass spectrometers, linear ion trap-Fourier transform (FT)-Orbi-trap mass spectrometers are also now being used for similar high resolution-full scan applications (6). Finally, while high resolution and full scan capabilities are being increasingly utilized in LC/MS applications, there are also new benefits being realized when used with GC/MS, including nontarget identification of brominated flame retardants and fungicides in water samples that were originally targeted for other contaminants (7). Researchers are also increasingly using isotopically labeled standards (deuterated or 13C-labeled) to allow more accurate quantitation in a variety of sample matrixes (especially for wastewater samples, where matrix effects and ion suppression can be substantial). Atmospheric pressure photoionization (APPI) is also increasingly being used with LC/MS because it provides improved ionization for more nonpolar compounds, such as nanomaterials (e.g., fullerenes) and polybrominated diphenyl ethers (PBDEs). Sampling and Extraction Trends. The use of molecularly imprinted polymers (MIPs) for selective extraction of environmental contaminants has experienced tremendous growth the last
2 years. MIPs are synthetic polymers made with specific recognition sites that are complementary in shape, size, and functional group to the analyte of interest. The recognition sites mimic the binding sites of antibodies and enzymes. Because they are highly specific to the target analytes of interest, MIPs can be used to extract and isolate them from other matrix components in a complex mixture. MIPs have now been synthesized for a number of emerging contaminants, including pharmaceuticals, pesticides and pesticide metabolites, endocrine disrupting compounds (EDCs), algal toxins, and organotins. A review by Pichon and ChapuisHugon discusses these applications, along with how they are synthesized (8). Solid phase extraction (SPE) cartridges remain the most popular means of extraction and concentration for most emerging contaminants, but this area continues to change also, as new sorbents are manufactured that offer improved recoveries for polar analytes, and dual-phase media are being used to capture a broader range of analytes within a single extraction. Solventless extraction techniques, such as solid-phase microextraction (SPME), single-drop microextraction (SDME), stir bar sorptive extraction, and hollow-fiber membrane microextraction, also continue to be used in many applications. Wardencki et al. (9) and Lambropoulou et al. (10) published reviews describing recent developments and trends in this area. Chromatography Trends. The fastest growing chromatography trend continues to be the use of ultraperformance liquid chromatography (UPLC). UPLC is a recently developed LC technique that uses small diameter particles (typically 1.7 µm) in the stationary phase and short columns, which allow higher pressures and, ultimately, narrower LC peaks (5-10 s wide). In addition to providing narrow peaks and improved chromatographic separations, UPLC can also dramatically shorten analysis times, often to 10 min or less. Waters Corp. was the first company to develop this technology, but other companies now offer similar systems. Ibanez et al. published a nice overview of applications of UPLC with TOF-MS for the rapid screening of multiclass organic pollutants in water (5). Other significant chromatography trends include the use of two-dimensional GC (GC × GC) and hydrophilic interaction chromatography (HILIC). GC × GC enables enhanced separations of complex mixtures through greater chromatographic peak capacity and allows homologous series of compounds to be easily identified. It also enables the detection of trace contaminants that would not have been identified through traditional GC. TOF-MS is often used as the detector for GC × GC because of its rapid acquisition capability. Semard et al. published a nice paper illustrating the use of GC × GC for screening contaminants in wastewater (12). HILIC is a new LC technique that provides improved separations and detection for highly polar compounds. The stationary phase in HILIC columns has a polar end group (such as an amino group), and retention is based on the affinity of the polar analyte for the charged end group of the column stationary phase. Examples of the use of HILIC in this review include the measurement of haloacetic acids in drinking water and the analysis of melamine-cyanuric acid complexes. Online Analysis. Online SPE coupled to LC/MS/MS is being increasingly used, as it provides high sensitivity and selectivity, minimum sample preparation, more reproducibility, and automa-
tion. Examples of new online SPE-LC/MS/MS methods discussed in this review can be seen in the section on Pharmaceuticals, Hormones, and Endocrine Disrupting Compounds. RodriguezMozaz et al. discuss the advantages and limitations of online SPELC/MS for measuring emerging contaminants in water (11). Emerging Contaminants. Four new classes of emerging contaminants are added to this Water Analysis review this year: sucralose, antimony, siloxanes, and musks. Sucralose (also known as Splenda or SucraPlus) is a relatively new artificial sweetener that is now being found in environmental waters and is recognized as persistent. Antimony is a well-known, historical contaminant, but new research shows that it can also be a contaminant in bottled water, leaching from polyethylene terephthalate (PET) plastic bottles, where it is used as a catalyst in the production of these plastics. Siloxanes are widely used in consumer products, such as cosmetics, deodorants, soaps, hair conditioners, hair dyes, car waxes, baby pacifiers, cookware, cleaners, furniture polishes, and water-repellent windshield coatings, and researchers are now finding them in environmental waters. Synthetic musks are widely used fragrance additives in perfumes, lotions, sunscreens, deodorants, and laundry detergents and are now known to be widespread in the environment and to accumulate in wildlife and humans. Other areas covered in this review again include new regulations and regulatory methods, nanomaterials, perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and other perfluorinated compounds (PFCs), pharmaceuticals, hormones, EDCs, drinking water disinfection byproducts (DBPs), sunscreens/UV filters, brominated flame retardants (including polybrominated diphenyl ethers), benzotriazoles, naphthenic acids, algal toxins, perchlorate, dioxane, pesticide degradation products and new pesticides, and microorganisms. These continue to be intense areas of research. An ongoing trend in research for most of these emerging contaminants continues to be investigating ways to remove them from environmental waters (e.g., through reverse osmosis, microfiltration, advanced oxidation, photolysis, microbial degradation, etc.). Because researchers often find that the contaminants are not completely mineralized with these removal techologies, the identification of intermediates and degradation products becomes important, as well as the toxicity evaluation of the treated waters to determine whether the treatment significantly reduced the toxicity. GENERAL REVIEWS This section includes general reviews relating to water analysis and emerging contaminants. Reviews that relate to specific areas (e.g., perfluorinated chemicals, pharmaceuticals, DBPs) can be found in those specific sections. Many reviews have been published over the last 2 years that relate to water analysis, and a few focus specifically on emerging contaminants. My other biennial review on Environmental Mass Spectrometry published in 2008 included mass spectrometry methods and studies of emerging contaminants that were published in 2006-2007 and included measurements of air, soil/sediment, biological samples, and water (2). There have been several other reviews on emerging contaminants. Giger wrote an excellent overview of advanced analytical methods for measuring hydrophilic and amphiphilic water contaminants (13). In this article, he mentions new developments, including online SPE-LC, large-volume injection, UPLC, highAnalytical Chemistry, Vol. 81, No. 12, June 15, 2009
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resolution-TOF-MS, two-dimensional LC/MS, two-dimensional GC/MS (GC × GC/TOF-MS), as well as new mass spectrometry developments, including linear ion traps and the Orbi-trap. Also included are highly descriptive polarity-volatility diagrams that provide nice visual representations linking specific groups of contaminants with key processes that determine their fate in the environment and give application ranges of GC and LC. Several important groups of emerging contaminants are also mentioned, including surfactants and their metabolites, EDCs, perfluorinated compounds, benzotriazoles, complexing agents, pharmaceuticals, iodinated X-ray contrast media, gasoline additives, DBPs, and algal toxins. Giger also introduces new contaminants to watch for, including a recent discovery of sucralose (artificial sweetener also known as Splenda) in environmental samples, as well as nanomaterials that could potentially enter the aquatic environment. La Farre´ et al. reviewed the fate and ecotoxicology of emerging contaminants, along with their metabolites and transformation products in the aquatic environment (14). Pharmaceuticals, hormones, perfluorinated compounds, drinking water DBPs, sunscreens/UV filters, benzotriazoles, and naphthenic acids were included, along with a nice summary of ecotoxicological effects reported for nanomaterials. Wells et al. published a review of the occurrence, fate, and treatment of emerging pollutants, covering papers published during 2006 (15). Trace organic chemicals in groundwater recharge was the focus of another review by DiazCruz and Barcelo´ (16). This review is very timely, as several countries, including the United States, have had stresses on their water sources due to population growth and drought and have had to use treated wastewater to recharge groundwater sources. This article includes a discussion of artificial recharge strategies, issues with groundwater contamination, and the fate and removal of contaminants in groundwater. Effect-directed analysis studies in Europe was the focus of another review by Brack et al., where ecotoxicological effects such as mutagenicity, aryl hydrocarbon receptor-mediated effects, endocrine disruption, and effects on green algae and invertebrates (17). Pollutants identified through these studies included natural and synthetic estrogens and androgens and substituted phenols, along with more traditional priority pollutants (e.g., polycyclic aromatic hydrocarbons, dioxins, furans, biphenyls, nonylphenol, pesticides). GC determination of persistent organic pollutants was the focus of another review by van Leeuwen and de Boer (18), who included a discussion of GC × GC, large volume injection, electron capture detection (ECD), MS/MS, TOF-MS, and highresolution-MS. Esteve-Turillas et al. reviewed the use of semipermeable membrane devices (SPMDs) as passive samplers for monitoring environmental contaminants (19). This review included sampling of emerging contaminants (e.g., UV filters, alkylphenol ethoxylate surfactants, triclosan, organotins, polar pesticides, musks), modifications of SPMDs to improve uptake of specific chemicals, and details for how to use SPMDs. Finally, atomic analysis reviews are also published annually. One of these by Butler et al. includes recent papers on the analysis of air, water, soils, plants, and geological materials (20). NEW REGULATIONS/REGULATORY METHODS New U.S. Drinking Water Regulations. A few developments in new regulations and regulatory methods have taken place in 4648
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Table 3. Recent U.S. Regulations rule/regulation Stage 2 D/DBP Rule Contaminant Candidate List (CCL)-3 Second Unregulated Contaminants Monitoring Rule (UCMR-2) The Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR)
Web site www.epa.gov/safewater/stage2 www.epa.gov/safewater/ccl/ ccl3.html#microbial www.epa.gov/safewater/ucmr/ ucmr2 www.epa.gov/safewater/lt2
the last 2 years that impact water analysis (Tables 3 and 4). The U.S. Environmental Protection Agency’s (EPA’s) Web site is a good source for obtaining details on regulations and regulatory methods: www.epa.gov. This Web site has a search function to allow easy access to this information, and it has links to the Federal Register, where the complete published rules can be obtained. A direct link to the Federal Register can also be made with the following address: www.gpoaccess.gov/fr. Currently, there are primary drinking water regulations for 92 contaminants, including 11 DBPs, 53 organic contaminants, 16 inorganic contaminants, 4 radionuclides, 7 microorganisms, and turbidity (www.epa.gov/ safewater/contaminants). The U.S. EPA has a Web site where local drinking water quality reports can be obtained (www. epa.gov/safewater/dwinfo). There were no new rules issued during the last 2 years for drinking water, but compliance monitoring has begun during this time for several recently issued rules (Table 3, discussed below). The Stage 2 Disinfectants (D)/DBP Rule. The Stage 2 D/DBP Rule is an extension of the Stage 1 Rule, which lowered permissible levels of trihalomethanes (THMs) to 80 µg/L and regulates five of the haloacetic acids (HAAs), bromate, and chlorite for the first time (www.epa.gov/safewater/stage2). This rule was published on January 4, 2006 (Table 5) and has a staggered compliance monitoring schedule, which gives more time for compliance for smaller water systems (Table 6). Final compliance with the new standards will be in 2012-2013, depending on the size of the population served by the systems. The Stage 2 D/DBP Rule maintains the Stage 1 Rule maximum contaminant levels (MCLs) for THMs and HAAs (Table 5) but requires that MCLs be based on locational running annual averages (i.e., each location sampled in the distribution system must comply on a running annual average basis). The reason for this change is that the running annual averages (used with the Stage 1 D/DBP Rule) permitted some locations within a water distribution system to exceed MCLs, as long as the average of all sampling points did not exceed the MCLs. As a result, consumers served by a particular section of the distribution system could receive water that regularly exceeded the MCLs. The Stage 2 D/DBP Rule is intended to target those higher DBP levels and reduce the variability of exposure for people served by different points in the distribution system. The Stage 2 D/DBP Rule maintains the MCLs for bromate and chlorite; however, the U.S. EPA plans to review the bromate MCL as part of their 6 year review process (additional details are available at www.epa.gov/safewater/stage2). The Second Unregulated Contaminants Monitoring Rule (UCMR-2). The UCMR-2 was published on January 4, 2007 (www.epa.gov/safewater/ucmr/ucmr2) and is an updated form of the original UCMR that was issued in 1999. Results from the
Table 4. New Regulatory Methods method
analytes
Web site
EPA Method 537 EPA Method 522 EPA Method 314.2
perfluorinated surfactants 1,4-dioxane perchlorate
www.epa.gov/microbes/ordmeth.htm www.epa.gov/microbes/ordmeth.htm www.epa.gov/safewater/methods/analyticalmethods_ogwdw.html
Table 5. DBPs Regulated under the Stage 2 D/DBP Rule DBP
MCL (mg/L)
total THMsa HAAsb bromate chlorite
0.080 0.060 0.010 1.0
a Total THMs are the sum of the concentrations of chloroform, bromoform, bromodichloromethane, and dibromochloromethane. b The HAAs are the sum of monochloro-, dichloro-, trichloro-, monobromo-, and dibromoacetic acids.
first monitoring effort of water treatment plants can be found at www.epa.gov/safewater/ucmr/ucm_rounds_1-2.html. The UCMR-2 requires drinking water utilities to monitor for 25 chemicals over a 12 month period between 2008-2010. Table 7 lists the contaminants to be monitored under the UCMR-2, along with their approved EPA methods. Originally, perchlorate was to be included in the list of contaminants (and it was included in the UCMR-1), but in response to comments received and after further consideration, the U.S. EPA decided not to include it in the final UCMR-2 (www.epa.gov/EPA-WATER/2007/January/Day-04/ w22123.htm). Several of these contaminants are PBDE flame retardants, nitrosamine DBPs, and pesticide degradation products that are also discussed in this review. This Rule allows the U.S. EPA to obtain occurrence data for priority unregulated contaminants that are being considered for regulation. The occurrence data are stored in the National Drinking Water Contaminant Occurrence Database (NCOD) and are used with health effects data to determine whether any should be regulated. This Rule helps to support the Safe Drinking Water Act and Amendments, which requires that, at least once every 5 years, the U.S. EPA identify a list of no more than 30 unregulated contaminants to be monitored. The UCMR-2 is divided up into List 1 and List 2 contaminants (Table 7). All public water systems serving more than 10 000 people and a representative sample of 800 systems serving 10 000 or fewer people are required to conduct Assessment Monitoring (List 1) during a 12-month period during January 2008-December 2010. All public water systems serving >100 000 people, along with 320 systems serving 10 001-100 000 people, and 480 selected systems serving 10 000 or fewer people are required to conduct the Screening Survey (List 2) during a 12month period during January 2008-December 2010. Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). The final LT2ESWTR was published on January 5, 2006 and is an extension of the former Long-Term 1 Rule. This Rule improves the control of microbial pathogens (including specifically Cryptosporidium) in drinking water and addresses risk trade-offs with disinfection byproducts (additional details available at www.epa.gov/safewater/disinfection/lt2). Monitoring start dates are staggered according to system size, such that the largest systems (serving at least 100 000 people) began monitoring in October 2006, and the smallest systems
(serving 80% removal of diatrizoate. The presence of humic substances also significantly enhanced the ozone degradation of ICM compounds. Ozonation led to major cleavage of ICM compounds and the release of inorganic iodine. Approximately 100% iodine was released from diatrizoate, but only 40% was released from iopromide and iomeprol. Five products were also prominent during the reaction, but their chemical structures were not determined. Seitz et al. also investigated the effect of ozone treatment on ICM and characterized byproducts formed from iomeprol (81). Byproducts were characterized using LC/MS and LC/MS/MS; aldehyde and carbonyl-containing structures were proposed. These byproducts were also subsequently detected in an outlet of an ozone reactor at a full-scale drinking water treatment plant in Germany. Finally, Stieber et al. investigated the dehalogenation of iopromide by zerovalent iron (82). In this study, zerovalent iron was found to deiodinate iopromide, both in water and urine, at an optimum pH of 3. Occurrence Studies of Other Pharmaceuticals. Researchers at the U.S. Geological Survey (USGS) recently published two large national reconnaissance surveys of pharmaceuticals, their metabolites, and other wastewater contaminants in groundwaters and untreated source waters for drinking water. In the groundwater study by Barnes et al., the pharmaceuticals were measured in 47 different groundwaters across 18 states in the U.S. (83). Contaminants were detected in 81% of the sites, with sulfamethoxazole (human and veterinary antibiotic) being the most frequently detected. LC/ESI-MS (single-stage MS) was used for the pharmaceutical measurements. In the study of untreated source waters, Focazio et al. also used LC/ESI-MS to measure 36 pharmaceuticals (including 21 antibiotics) in 25 groundwater and 49 surface water sources for drinking water supplies across 4658
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the United States, including Hawaii and Puerto Rico (84). A total of 13 pharmaceuticals were found in at least 1 source water, but the majority (60%) were not detected in any sample. Carbamazepine and 1,7-dimethylxanthine were the pharmaceuticals detected the most often, at levels up to 0.19 and 0.30 µg/L, respectively. Sacher et al. published results from an extensive monitoring program in Europe for the River Rhine, with results for the past decade of measurements (85). Analgesics, lipid regulators, antiepileptics, and other pharmaceuticals were included in this survey; carbamazepine and diclofenac were among those most regularly found, up to several hundred nanogram per liter. Pharmaceutical levels decreased only slightly over this time period, and seasonal variations were observed for bezafibrate, diclofenac, and ibuprofen, which are found at lower levels during the summer. Research on pharmaceuticals continues to expand to new countries, including those in the Far East, Southeast Asia, and Eastern Europe. For example, Choi et al. investigated seasonal variations in pharmaceuticals in river water samples and sewage treatment plants in Korea and found cimetidine at high levels (5.38 µg/L) in plant effluents, along with sulfamethoxazole (193 ng/L) and carbamazepine (111 ng/L) (86). Cimetidine was also found at highest levels in surface waters (average of 281 ng/L), which is the highest reported for any country to-date. Moldovan et al. reported the first measurement of pharmaceuticals and personal care products in the Somes River watershed of Romania (87). Carbamazepine, pentoxyfylline, ibuprofen, diazepam, galaxotide, tonalide, and triclosan were measured in wastewater effluents at levels ranging from 15 to 774 ng/L; caffeine was found up to 42.5 µg/L. The most abundant compounds found in river water were caffeine, galaxolide, carbamazepine, and triclosan, at levels ranging from 10 to 400 ng/L. Finally, Managaki et al. investigated the distribution of 12 antibiotics in the Mekong Delta of Vietnam (88). LC/MS/MS was used to measure these antibiotics, and their distribution was compared to those found in a river in Japan. In Vietnam, only a few antibiotics were detected in the river and canals from urban and rural sites, at concentrations ranging from 7 to 360 ng/L. In contrast, a larger number of antibiotics were found in river water from Japan, at levels ranging from 4 to 448 ng/L. Waters in Vietnam did have an unusually high level of the veterinary antibiotic sulfamethazine (up to 328 ng/L in river water and up to 19.2 µg/L in pig farm wastewaters). Fate and Transport Studies. Several excellent fate and transport studies have been published in the last 2 years. Some of these involve environmental fate (in agricultural runoff, biodegradation, photolysis), and others involve fate in septic system plumes and in wastewater treatment. Gulkowska et al. investigated the removal of nine antibiotics from wastewater treatment plants in Hong Kong and in Shenzhen, China, a major port city across the border from Hong Kong (89). Cefalexin concentrations were highest in the samples from Hong Kong, ranging from 670 to 2900 and 240 to 1800 ng/L in the influents and effluents, respectively, whereas this antibiotic was not detected in the samples from Shenzhen. However, high levels of another antibiotic, cefotaxim, did occur at relatively high levels in wastewater influents (mean concentration of 1100 ng/L). These results demonstrated different regional variations in prescription and use patterns between Hong Kong and Shenzhen. In addition antibiotics were removed more
efficiently in Hong Kong treatment plants, which used secondary treatment processes compared to only primary treatment in Shenzhen. Wastewater treatment plants were investigated in Finland by Vieno et al. (90). Eight pharmaceuticals (β-blockers, an antiepileptic, and fluoroquinolone antibiotics) were measured in the influents and effluents of 12 sewage treatment plants. Fluoroquinolones were eliminated by >80% and β-blockers by approximately 65% in these plants, but levels of carbamazepine actually increased in concentration in many of the treated effluents, suggesting an enzymatic cleavage of the glucuronic conjugate of carbamazepine and release of the parent compound. The removal of antibiotics in wastewater treatment was also investigated in Australia by Watkinson et al. (91). In this study, 28 human and veterinary antibiotics were measured in conventional (activated sludge) and advanced (MF/RO) wastewater treatment in Brisbane. The dominant antibiotics in the influents were cephalexin (median of 4.6 µg/L), ciprofloxacin (median of 3.8 µg/L), cefaclor (median of 0.5 µg/L), sulfamethoxazole (median of 0.36 µg/L), and trimethoprim (median of 0.34 µg/L), with each of these found in all of the samples collected. Most of these antibiotics were removed by 92% in both treatment plants; however, antibiotics were still detected in both effluents at low to mid-nanogram per liter. Therefore, even RO does not provide complete removal of these compounds. Septic system plumes in Ontario, Canada, were the focus of another fate study by Carrara et al. (92). A total of 12 different pharmaceuticals were measured using liquid-liquid extraction, derivatization with pentafluorobenzyl bromide (PFBBr), and GC/ MS. Samples were collected from the septic tanks and from groundwater samples below and down gradient of the infiltration beds. A total of 10 of the 12 pharmaceuticals were detected in groundwater at one or more sites, at levels ranging from low nanogram per liter to low microgram per liter. Ibuprofen, gemfibrozil, and naproxen were transported at the highest concentrations and greatest distances, particularly in the anoxic zones of the plumes. Runoff from agricultural fields was the focus of another study by Topp et al., who investigated pharmaceutical and personal care products (PPCP) runoff following application of biosolids by either subsurface injection or broadcast application (93). PPCPs were generally not detected in the samples collected after subsurface treatment, but levels were high following broadcast application (70-1477 ng/L) and generally decreased with time. Carbamazepine and triclosan were still detected 266 days after application. Overall, this study showed that injection of biosolids slurry below the soil surface can effectively eliminate surface runoff. Photolysis of three pharmaceutical metabolites was investigated by Gomez et al. (94). The fate of the metabolites of the analgesic and antipyretic drug dipyrone, 4-methylaminoantipyrine (4-MAA), 4-formylaminoantipyrine (4-FAA), and 4-acetylaminoantipyrine (4-AAA), were evaluated under simulated solar irradiation. 4-MAA was easily photolyzed, with a half-life of 0.12-0.58 h, depending on conditions, whereas 4-FAA and 4-AAA were degraded more slowly, with half-lives of 24 and 28 h, respectively. GC/MS and LC/TOF-MS were then used to elucidate the structures of several of the photodegradation products, which were more toxic in Daphnia magna than the parent metabolites. In another study by Radjenovic et al., UPLC/Q-TOF-MS and LC/
quadrupole ion trap-MS were used to structurally characterize biodegradation products of the β-blocker atenolol and the hypoglycemic agent glibenclamide (95). Biodegradation studies were carried out in a batch reactor under aerobic conditions, using sewage sludge from a conventional plant and a laboratory-scale membrane bioreactor. The primary biodegradation product of atenolol was identified as atenolic acid, resulting from bacterial hydrolysis of the amide bond, and the primary product from glibenclamide was identified as glibenclamide hydroxide. Atenoloic acid was subsequently found in real wastewater samples, along with atenolol. When treated in the membrane bioreactor, atenolol and its metabolite can be completely eliminated but the hydrolyzed metabolite of glibenclamide was persistent. Other Treatment Studies. As with the ICM compounds, several studies have focused on ways to remove pharmaceuticals from environmental waters. In a nice review article by Joss et al., different treatment options, along with their feasibility, are discussed for removing organic micropollutants, including pharmaceuticals (96). Also, additional measures are recommended that can help to reduce environmental levels, including control of sources from leaking pipes, combined sewer overflows, agricultural runoff, leaching from landfills, as well as limiting use of environmentally harmful consumer chemicals, ecolabeling of products, and treatment at the source (e.g., separate treatment for industrial wastewater, hospitals, and nursing homes). Ozonation and UV treatment at a drinking water treatment plant were investigated in another study by Vieno et al. (97). Following ozonation, most pharmaceuticals, including four β-blockers, one antiepileptic, one lipid regulator, four anti-inflammatories, and three fluoroquinolones were removed to below detection with a dose of 1 mg/L. Pereira et al. evaluated UV photolysis and UV/ H2O2 oxidation for degrading pharmaceuticals in water (98). Overall, medium-pressure UV lamps proved to be effective for decomposing ketoprofen, naproxen, carbamazepine, ciprofloxacin, clofibric acid, and iohexol with both UV photolysis and also with UV/H2O2 oxidation. Canonica et al. investigated the phototransformation of four pharmaceuticals (EE2, diclofenac, sulfamethoxazole, and iopromide) with UV treatment (99). Direct phototransformation was observed for diclofenac, sulfamethoxazole, and iopromide, whereas EE2 underwent indirect phototransformation in natural waters. Overall, the degradation of these chemicals was low (0.4-27%) at a UV dose that would be typically used in drinking water treatment. Three different recycling schemes (two using RO and the other using ozonation and biological activated carbon filtration) were investigated in Australia for removing organic contaminants, including 11 pharmaceuticals and 2 nonsteroidal estrogenic compounds, in a paper by Al-Rifai et al. (100). Derivatization with GC/MS and selected ion monitoring was used to measure them. All treatment schemes were able to remove >90% of the pharmaceuticals, except for ketoprofen (80%). Of the treatments investigated, RO was the most effective. Stackelberg et al. investigated conventional drinking water treatment (clarification, chlorination, and granular activated carbon [GAC] filtration) as a means to remove pharmaceuticals and other organic compounds (101). GAC filtration removed 53%, chlorination removed 32%, and clarification, 15%. However, 21 of the 113 organic compounds Analytical Chemistry, Vol. 81, No. 12, June 15, 2009
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studied were detected in one or more of the finished drinking water samples; camphor and DEET were the most persistent. New Methods. New methods reported include those using UPLC/MS/MS, LC/TOF-MS with accurate mass, and online-SPE/ LC/MS/MS. The recent development of UPLC has allowed vastly improved chromatographic resolution (as compared to conventional LC), very short run times (often less than 10 min), and the minimization of matrix effects. A new UPLC/MS/MS method was developed for stimulatory drugs of abuse, including cocaine, amphetamine-related drugs, LSD, ketamine, PCP, fentanyl, and metabolites (102). Chromatographic separation was achieved in bromoiodoacetic acid > (E)-2-iodo-3-methylbutenedioic acid > (E)3-bromo-3-iodopropenoic acid > (E)-3-bromo-2-iodopropenoic acid. The rank order of cytotoxicity was iodoacetic acid > (E)-3-bromo2-iodopropenoic acid > iodoform > (E)-3-bromo-3-iodopropenoic acid > (Z)-3-bromo-3-iodopropenoic acid > diiodoacetic acid > bromoiodoacetic acid > (E)-2-iodo-3-methylbutenedioic acid > bromodiiodomethane > dibromoiodomethane > bromochloroiodomethane. Liquid-liquid extraction and diazomethane derivatization was used with GC/negative chemical ionization (NCI)MS to quantify the iodo-acids at low nanogram per liter detection limits; SPME with GC/high resolution-EI-MS was used to quantify two iodo-THMs (dichloroiodomethane and bromochloroiodomethane) at 2 ng/L detection limits. Iodo-acids were found in finished drinking waters from all of the 23 cities sampled in the U.S. and Canada, up to 1.7 µg/L; iodo-THMs were also found in most finished waters, up to 10.2 µg/L. The use of chloramination clearly increased their formation relative to chlorination, and shorter free chlorine contact times (before ammonia addition to form chloramines) resulted in higher levels of iodo-DBPs. These results confirm earlier controlled laboratory results of iodoform formation previously conducted in von Gunten’s research group. Haloamides were the subject of another recent combined chemistry-toxicology study, where a new iodinated haloamide was identified for the first time in chloraminated drinking water using GC/electron ionization (EI)-MS: bromoiodoacetamide (140). This standard was synthesized, and key mass spectral ions were analyzed under selected ion monitoring (SIM) conditions to maximize detection. Bromoiodoacetamide was detected in chloraminated drinking waters from 12 treatment plants (from 6 U.S. states). This iodinated haloamide was extremely cytotoxic and genotoxic in mammalian cells, as were several of the other haloamides studied. Finally, results from the first phase of a large integrated study (called the Four Lab Study) involving the collaboration of chemists, toxicologists, engineers, and risk assessors from the four national laboratories of the U.S. EPA, as well as collaborators from academia and the water industry, was published in a series of papers in a special issue of Journal of Toxicology and Environmental Health. The Four Lab Study aims at understanding reproductive and developmental effects, as well as other toxicological effects, that have been observed in humans, and involved the treatment of natural waters with two disinfection regimes: (1) chlorine and (2) ozone-chlorine. More than 70 priority DBPs were quantified using GC/ECD and GC/MS methods, and DBPs were also identified in a comprehensive approach using GC/EI-MS and GC/CI-MS with low and high resolution (141). Several new DBPs were identified in this effort, including bromo- and chloro-acids, iodinated compounds, bromoand iodo-phenols, and bromoalkyltins.
Nitrosamines. Nitrosamines have become a hot area of research recently, since they were discovered to be DBPs in 2002. NDMA is a probable human carcinogen, and there are toxicological concerns regarding other nitrosamines. NDMA was initially discovered in chlorinated drinking waters from Ontario, Canada, and has since been found in other locations. The detection of NDMA in drinking water is largely due to improved analytical techniques that have allowed its determination at low nanogram per liter concentrations. NDMA is generally present at low nanogram per liter concentrations in chloraminated/chlorinated drinking water, but it can be formed at much higher levels in wastewater treated with chlorine. NDMA is not currently regulated in the United States for drinking water but is included on the second Unregulated Contaminants Monitoring Rule (UCMR-2) along with five other nitrosamines (N-nitrosodiethylamine, Nnitrosodibutylamine, N-nitrosopropylamine, N-nitrosomethylethylamine, and N-nitrosopyrrolidine), where drinking water occurrence data is being collected on a national scale (www.epa.gov/ safewater/ucmr/ucmr2/basicinformation.html#list). In addition, NDMA and four other nitrosamines are also listed on the current proposed CCL-3 (Table 8). Ontario has issued an interim maximum acceptable concentration for NDMA at 9 ng/L (www. ene.gov.on.ca/envision/gp/4449e.pdf). Thus, it has been known for a few years that nitrosamines can form in drinking water treatment with chloramine or chlorine, but a surprising new discovery from drinking water in Germany reveals that it can also form with ozonation, which was not expected from previous research. To that end, Schmidt and Brauch reported the discovery of NDMA in ozonated drinking water, which had agricultural inputs into its source waters (142). Upon investigation, it was discovered that the source waters contained a fungicide, tolylfluanide, which can microbially degrade to form N,N-dimethylsulfamide (DMS). DMS, which was found at 100–1000 ng/L in groundwaters and 50–90 ng/L in surface waters, can then subsequently react with ozone to form NDMA. During ozonation, approximately 30-50% of the DMS is converted to NDMA and DMS cannot be removed easily by riverbank filtration, activated carbon filtration, flocculation, or oxidation with hydrogen peroxide, permanganate, chlorine dioxide, or UV irradiation. This finding is particularly interesting because other researchers had predicted the potential for formation of NDMA with ozone if compounds containing dimethylamine (DMA) were present. This potential was recently detailed in controlled laboratory studies of DMA by Andrzejewski et al. (143). Similarly, Chen and Young report a new discovery of NDMA formation from the chlorination or chloramination of diuron, a widely used herbicide that also contains a DMA functional group (144). Diuron formed NDMA with chlorine in the absence of ammonia, indicating that the nitrogen atoms in NDMA come from diuron. A potential reaction pathway was proposed from these controlled laboratory experiments. Strong base anion-exchange resins were investigated as precursors to nitrosamines and other N-DBPs in a new study by Kempter et al. (145). These resins (which contain quaternary amine functional groups) represent an important option for water utilities and homeowners to address growing concerns with nitrate, arsenate, and perchlorate contamination. Nitrosamines were released from the resins when they were new (up to 10 ng/ Analytical Chemistry, Vol. 81, No. 12, June 15, 2009
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L), but levels decreased with time after multiple regeneration cycles, indicating that releases may eventually subside. When chlorinated or chloraminated water was passed through the resins, nitrosamine levels increased to 20-100 ng/L. Dimethylnitramine (DMNA) was also formed with chlorine at significant levels; trichloronitromethane (chloropicrin) was formed to a lesser extent. EPA Method 521 (GC/CI-MS/MS) was used to measure nitrosamines and DMNA. Fortunately, no N-DBPs were found in the cation-exchange-based point-of-use devices that are used by homeowners. In other NDMA studies, Zhao et al. investigated the formation of nitrosamines from 11 disinfection treatments of 7 different source waters in a controlled laboratory study (146). Treatments included chlorine (hypochlorite), chloramine, chlorine dioxide, ozone, UV, advanced oxidation processes, and their combinations. Nitrosamines were measured using SPE and LC/MS/MS. All disinfectants formed NDMA in at least some of the source waters investigated, up to 118 ng/L, with highest levels from chloramination. NDPhA was formed by chlorine, chloramine, ozone, and medium pressure (MP)-UV/chlorine. N-Nitrosomethylethylamine (NMEA) was formed by chlorine and MP-UV/chlorine. Nnitrosomorpholine (NMor) was formed by ozone. UV treatment alone was found to degrade NDMA, but when followed by chlorination or when advanced oxidation (hydrogen peroxide) was used with UV and chlorine, higher amounts of NDMA were formed, indicating that advanced oxidation may produce NDMA precursors. Schreiber and Mitch investigated the formation of nitrosamines during breakpoint chlorination (147). This study found that nitrosamine formation near the breakpoint was more than an order of magnitude higher than observed during chloramination, and mechanisms were proposed. In another study, Pehlivanoglu-Mantas and Sedlak investigated the forms of dissolved organic nitrogen (DON) that can contribute to NDMA formation in wastewater treated with different methods (148). Hydrophilic, low molecular weight compounds were found to be the major precursors for NDMA, with amino acids contributing another 10-20% and humic substances another few percent. A few new methods have been developed for nitrosamines using GC/high-resolution-MS, LC/MS/MS, LC/UV-luminescence, and nano-ESI-high-field asymmetric waveform ion mobility spectrometry (FAIMS)-MS/MS. Planas created an automated SPE and isotope dilution-GC/high-resolution-MS method for measuring nine nitrosamines in water (149). This method offered increased selectivity and sensitivity, with method detection limits (MDLs) ranging from 0.08 to 1.7 ng/L. This method was then used to measure nitrosamines in finished drinking water, sewage treatment plant effluent, and a chlorinated reservoir sample. NDMA and NDEA were the predominant nitrosamines measured, up to 730 ng/L in sewage effluents and >10 ng/L in drinking water and chlorinated reservoir samples. Highest levels resulted from chlorination and ozonation. Plumlee et al. created a LC/MS/MS method for measuring six nitrosamines at low nanogram per liter levels (150). With the use of this method, the removal of NDMA and other nitrosamines was investigated at an advanced wastewater treatment facility that uses MF, RO, and UV-H2O2. Removals using RO and UV were 24-56% and 43-66%, respectively. Kodamatani et al. created a LC-online-UV-luminol chemiluminescence method for measuring four nitrosamines: 4664
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NDMA, NMor, NMEA, and N-nitrosopyrrolidine (NPYR) at low nanogram per liter detection limits in water, with no preconcentration (151). Finally, Zhao et al. developed a method using nano-ESI-FAIMS-MS/MS to measure seven nitrosamines in water (152). FAIMS reduced background interferences and improved the signal-to-noise as much as 10× over nano-ESIMS/MS. New Methods. Total adsorbable organic iodine (TAOI) was the focus of another method by Fono and Sedlak (153). While this method was primarily created for measuring ICM pharmaceuticals in wastewater, it could also be used to measure organic iodine DBPs in drinking water. This was a simple method that liberates iodide with Cu(II) and hydrogen peroxide and uses LC-UV for detection. A new method for bromate, iodate, bromide, and iodide was developed by Reddy-Noone et al., who used liquid phase microextraction-GC/MS (154). Detection limits ranged from 10 to 20 ng/L. Zhang et al. used paired precursor ion scans of m/z 79 and 81 with LC/ESI-MS/MS to allow unknown brominated DBPs to be detected and identified (155).With this method, many highly polar bromine-containing DBPs were tentatively identified in drinking water samples. HAAs were the focus of two new methods. The first, by Chen et al., utilized UPLC/MS/MS and reported 1-3 µg/L detection limits (156). HILIC and BetaMax Acid columns were tested, and while the HILIC UPLC column provided lower on-column detection, it required the dilution of water samples in acetonitrile; therefore, the BetaMax Acid UPLC column was best. Cardador et al. used liquid-liquid microextraction/methylation for measuring HAAs in drinking water with headspace-GC (157). Low detection limits of 0.02-0.4 µg/L were achieved. GC/FTion cyclotron resonance (ICR) MS was used by Heffner et al. for accurate mass measurements to enable the identification of new DBPs (158). SPME-GC/TOF-MS was used in another method created by Niri et al. for the rapid measurement of DBPs and other volatiles (159). A new realtime method was created by Brown et al. for measuring THMs in drinking water distribution systems (160). This method used automated online purge-and-trap-GC with a dry electrolytic conductivity detector. THMs were pervaporated through a silicone capillary membrane, preconcentrated using a sorbent trap, and analyzed with GC/conductivity. MDLs of 0.5 kDa) precursors formed more unknown TOX than hydrophilic and low MW precursors. Trihaloacetic acid precursors were more hydrophobic than THM precursors, and dihaloacetic acid yields were highest for hydrophilic/low MW precursors. In addition, bromine and iodine were more reactive with hydrophilic/low MW precursors. The formation of brominated DBPs (including bromate and brominated THMs) from TiO2/UV and UV treatment was the subject of other studies. Espinoza and Frimmel irradiated TiO2 suspensions containing bromide and dissolved organic carbon (DOC) and found no detectable bromate or THMs, even up to 10 mg/L of bromide (166). This suggests that, in contrast to chlorination, it might be possible to oxidize organic material by photocatalysis while minimizing brominated DBP formation. Chow et al. studied the impact of simulated solar irradiation on DBP precursors in water collected from three sites in the Sacramento-San Joaquin Delta in California (167). Solar irradiation significantly decreased UV absorbance and fluorescence intensity, produced organic acids, and increased the hydrophilic fraction in the waters studied. These changes in DOC resulted in a shift toward more brominated species of THMs and HAAs after chlorination and demonstrates how sunlight can alter DOC with respect to DBP formation. Model Compound Studies. Several researchers used model compounds to better understand DBP formation. For example, Joo and Mitch studied nitrile, aldehyde, and halonitroalkane formation during chlorination or chloramination of primary amines (168). Primary amine precursors were studied because they are important groups in biomolecules present in source waters. Chlorine and chloramines transformed primary amines to nitriles and aldehydes in significant yields over time scales relevant to drinking water distribution systems. Tertiary alkylamines were investigated in another study by Mitch and Schreiber (169). During chlorination, the tertiary alkylamines degraded nearly instantaneously to form aldehydes and secondary alkylamines. Chloramination also formed them but at lower rates. It was postulated that these secondary alkylamines may be NDMA precursors. The formation of halogenated aldehydes from the chlorination of acetaldehyde was the focus of another study by Koudjonou et al. (170). Trichloroacetaldehyde (chloral hydrate) was the most common halogenated aldehyde observed in these
reactions, but with increased pH and temperature, it can degrade to form chloroform and other unidentified compounds. Arnold et al. used compound specific isotope analysis (using an isotope ratio-mass spectrometer) to monitor the δ13C signature of chloroform produced upon the chlorination of model compounds representing different NOM functional groups (resorcinol, acetylacetone, acetophenone, phenol, and 2,4,6trichlorophenol) and a natural water sample (171). The signature isotope effect for chloroform in the chlorinated natural water sample matched that of the phenols, indicating that phenols are likely chloroform precursors in NOM. Carbohydrates were examined as potential THM precursors in a study by Navalon et al., who also investigated the effect of pH and chloride/bromide ions (172). The carbohydrates were found to be significant precursors for THMs, and the presence of bromide produced higher levels of THMs. Remarkably, bromide levels 100 ng/L (and up to 310 ng/L). As expected, brominated-MX compounds were formed in waters with higher bromide levels and chlorination formed higher levels than chloramination, but chloramines appeared to stabilize MX analogues in the distribution system. Pretreatment with ozone and GAC minimized MX formation upon subsequent chlorination or chloramination but pretreatment with chlorine dioxide did not. In chlorinated drinking waters, MX analogues showed similar formation patterns to THMs and HAAs, suggesting a common formation mechanism. The occurrence and fate of DBPs in bottled waters was the focus of a study by Leivadara et al., who measured THMs, HAAs, haloacetonitriles, and halopropanones in several bottled waters from Greece (175). DBPs were measured immediately after purchase and after 3 months of storage, either at room temperature or in outdoor conditions, exposed to sun and temperatures up to 30 °C. Levels of THMs ranged from nondetect to 21.7 µg/L (chloroform). Levels of HAAs ranged from nondetect to 4.0 µg/L (DCAA). Interesting trends were observed: chloroform, bromodichloromethane, bromochloroacetic acid, dibromoacetic acid, and 1,1,1-trichloropropanone were not initially detected in the bottled waters sampled immediately after purchase, but were detected in later samplings of the same water that had been exposed to outdoor conditions (increased temperature and 3-month storage). In contrast, DCAA and trichloroacetic acid levels declined after storage, suggesting that they may decompose to other DBPs. It had been reported previously that trichloroacetic acid can decompose to chloroform. The haloacetonitriles also decreased over storage. Analytical Chemistry, Vol. 81, No. 12, June 15, 2009
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New Swimming Pool Research. Swimming pools have been recently recognized as an important source of exposure to DBPs. A new epidemiologic study by Villanueva et al. not only showed an increased risk of bladder cancer for ingestion of chlorinated drinking water and inhalation/dermal exposures from showering and bathing, but also an increased risk for swimming in pools and developing bladder cancer (176). In addition, epidemiologic studies have also shown increased risk of asthma both for indoor pools (177) and, more recently, in outdoor pools (178). Results from a workshop report were recently published on childhood asthma and environmental exposures at swimming pools, where the state of the science is outlined, along with research recommendations (179). Zwiener et al. also published an article on swimming pool waters, detailing adverse health effects (including asthma, bladder cancer, and endocrine effects) and the formation of DBPs, including those comprehensively identified in actual swimming pools and brominated DBPs formed by the reaction of chlorine, bromide, and sunscreens (180). Three important swimming pool DBP occurrence studies have recently been published. Li and Blatchley used membrane introduction mass spectrometry (MIMS) to measure volatile DBPs in a controlled laboratory study with four model compounds (creatinine, urea, L-histidine, and L-arginine), which are found in human sweat and urine and in actual pool water (181). Trichloramine, dichloromethylamine, and dichloroacetonitrile were found in actual swimming pool waters; this is the first report of dichloromethylamine as a DBP in swimming pool water. In addition, trichloramine was formed by the chlorination of all four model compounds; dichloromethylamine was formed by the chlorination of creatinine; and cyanogen chloride and dichloroacetonitrile were formed by the chlorination of L-histidine. Walse and Mitch published an excellent paper entitled, “Nitrosamine carcinogens also swim in chlorinated pools”, which details a study of nitrosamines in pools, hot tubs, and aquaria (182). NDMA and seven additional nitrosamines were measured using GC/CI-MS/MS (EPA Method 521). NDMA was found in chlorinated swimming pools and hot tubs at levels up to 500× greater than the level (0.7 ng/L) associated with a one in a million lifetime cancer risk. NDMA levels in indoor pools (32 ng/L median, 44 ng/L maximum) were 6× greater than in outdoor pools (5.3 ng/L median, 6.9 ng/L maximum), and NDMA levels in hot tubs at ∼41 °C (313 ng/L median, 429 ng/L maximum) were approximately 10× greater than those in indoor swimming pools. N-Nitrosodibutylamine and N-nitrosopiperidine were also detected, but together represented 3900 µg/L in cyanobacterial blooms collected near the shoreline. A new UPLC/MS/MS method was reported by Wang et al. for measuring microcystins in water (246). SPE allowed 1000× concentration, and limits of quantification for the four microcystins (microcystin-LR, -RR, -LW, and -LF) were 2.5, 6.0, 2.5, and 1.3 ng/L, respectively. This method was used to measure microcystins in drinking water reservoirs, river water, and lake water in China. Microcystin contamination in the drinking water reservoirs was the highest (up to 2.73 µg/L), with microcystinLR and -RR the predominant ones found. Howard and Boyer developed a new method for simplifying adduct patterns observed with MALDI-TOF-MS for microcystins (247). The addition of zinc sulfate heptahydrate to samples, prior to spotting on the target, significantly enhanced the detection of the protonated molecule while suppressing competing adducts. This produced a highly simplified mass spectrum with potential to improve quantitative analysis, particularly for complex samples. New studies have also investigated ways to eliminate algal toxins, including microbial degradation and advanced oxidation. Kato et al. investigated the microbial degradation of cyanobacterial cyclic peptides other than microcystins and nodularins (248). Bacterial strain B-9, which had been previously shown to hydrolyze microcystins and nodularins with its intracellular enzymes, was isolated from a eutrophied lake and was used for this microbial degradation study. The toxins evaluated included nostophycin, microcyclamide, aeruginopeptin 95-A, microviridin I, and anabaenopeptin A. LC/ion trap-MS/MS was used to analyze their degradation products. Bacterial strain B-9 was effective for degrading these algal toxins through hydrolysis of their peptide bonds, and several degradation products were found. TiO2/UV photocatalysis has also been studied to degrade algal toxins, such as microcystin-LR, and Antoniou et al. used LC/MS/MS to identify intermediates formed during this process (249). Most of these intermediates have not been reported in previous studies. Results showed that microcystin-LR degradation is initiated at four sites on the toxin: three sites on the Adda amino acid (aromatic ring, methoxy group, and conjugated double bonds) and one on the cyclic structure (Mdha amino acid). Several other geometric isomers were also formed. The reactions involved hydroxyl radical addition/substitution, oxidation, and bond cleavage. This is the first study to report the hydroxylation of the aromatic ring and the demethoxylation of microcystin-LR with TiO2/UV. Detailed reaction mechanisms are proposed for the formation of these intermediates, which still have rather high molecular weights (>750 Da). Finally, Rodriguez et al. examined different oxidative techniques, using ozone, chlorine, chlorine dioxide, and permanganate, Analytical Chemistry, Vol. 81, No. 12, June 15, 2009
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to eliminate three cyanotoxins: microcystin-LR, cylindrospermopsin, and anatoxin-a (250). Controlled kinetic experiments were carried out with these algal toxins, and LC with diode array detection was used for their analysis. In addition to experiments carried out in pure (Milli-Q) water, natural lake waters were also examined. Overall, it was found that permanganate can effectively oxidize anatoxin-a and microcystin-LR; chlorine can oxidize cylindrospermopsin and microcystin-LR; and ozone can effectively oxidize all three toxins with the highest rate. However, if chlorine is used, it must be used at levels
