环境质谱分析：紧急污染物
Environmental Mass Spectrometry: Emerging Contaminants and Current Issues #LV n6A]!I)U2{ a d\ o I c;^
BackgroundThis biennial review covers developments in environmental mass spectrometry for emerging environmental contaminants over the period of 2006−2007. A few significant references that appeared between January and February 2008 are also included. [i]Analytical Chemistry[/i]'s current policy is to limit reviews to a maximum of 250 significant references and to mainly focus on new trends. As a result, as was done in the previous 2006 environmental mass spectrometry review [url=http://pubs.acs.org/cgi-bin/asap.cgi/ancham/asap/html/ac800660d.html#ref1][color=#0066cc]1[/color][/url], this 2006 review will be limited to new, emerging contaminants, and environmental issues that are driving most of the current research. Even with a more narrow focus, only a small fraction of the quality research publications could be discussed. Thus, 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 water analysis, which also focuses on emerging contaminants [url=http://pubs.acs.org/cgi-bin/asap.cgi/ancham/asap/html/ac800660d.html#ref2][color=#0066cc]2[/color][/url]. That review article is somewhat different from this one, in that it covers other analytical techniques in addition to mass spectrometry, and it focuses only on the analysis of water. This review on Environmental Mass Spectrometry focuses on methods and occurrence/fate studies utilizing mass spectrometry, but also includes the study of air, soil/sediment, and biological samples, in addition to water. I welcome any comments you have on this review ([email]richardson.susan@epa.gov[/email]).%i T.I1fy x `+H}
Numerous abstracts were consulted before choosing the best ones to present here. Abstract searches were carried out using [i]Web of Science[/i], and in many cases, full articles were obtained. A table of acronyms is provided (Table [url=http://pubs.acs.org/cgi-bin/asap.cgi/ancham/asap/html/ac800660d.html#tbl1][color=#0066cc]1[/color][/url]) as a quick reference to the acronyms of analytical techniques and other terms discussed in this review.
[b]Mass Spectrometry Detection Trends.[/b] There is a tremendous increase in the use of time-of-flight (TOF)-mass spectrometry (MS) and quadrupole (Q)-TOF-MS for structural elucidation and compound confirmation. TOF-MS and Q-TOF-MS provide increased resolution capability (typically 10 000−12 000 resolution), which allows precise empirical formula assignments for unknowns and also provides extra confidence for positive identifications in quantitative work. This benefit of TOF-MS and Q-TOF-MS can be seen particularly in the sections on pharmaceuticals, endocrine disrupting compounds (EDCs), and pesticide degradation products. Nearly all new research on the identification and study of environmental transformation products has involved Q-TOF or another form of high-resolution MS. In addition, liquid chromatography (LC)/electrospray ionization (ESI)- and atmospheric pressure chemical ionization (APCI)-MS methods continue to dominate the new methods developed for emerging contaminants, and the use of multiple reaction monitoring (MRM) with MS/MS has become commonplace for quantitative environmental analysis. The use of LC/MS/MS allows the identification of highly polar organic pollutants without derivatization, down to nanogram per liter levels in environmental samples. Also, the use of MRM provides increased selectivity and sensitivity, greatly reducing the chemical background in LC/MS analyses. 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 and biological samples, where matrix effects 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)."qQH5x2F)R
[b]Sampling and Extraction Trends.[/b] Trends in sampling and extraction include increased use of stir bar sorptive extraction and hollow-fiber microextraction. Examples of stir bar sorptive extraction presented in this review include the extraction of UV filters and polybrominated diphenyl ethers (PBDEs); the use of hollow fiber extraction can be seen in this review in the section on brominated flame retardants. Stir bar sorptive extraction involves the use of a sorbent-coated stir bar, which is stirred in the aqueous sample to extract the analytes of interest. The analytes are then thermally desorbed and analyzed by gas chromatography (GC)/MS. Hollow-fiber microextraction is similar to traditional SPME, except that a polypropylene hollow fiber is attached to the tip of a syringe that contains an extraction solvent (typically, a nonpolar solvent, such as decane). The membrane is then used to extract the aqueous sample, the solvent is drawn back into the syringe, the fiber discarded, and the solvent injected directly into a GC or LC instrument. Traditional solid phase microextraction (SPME), which eliminates the need for organic solvents in extraction, has now become commonplace, and examples are presented throughout this review. In addition, Oasis HLB solid phase extraction (SPE) cartridges have become very popular for extracting highly polar compounds from water, especially in pharmaceutical research.
[b]Chromatography Trends.[/b] One of the fastest growing trends in chromatography is 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 are now offering similar systems. An example of UPLC presented in this review is the measurement of illicit drugs in environmental samples. 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. An example of GC × GC presented in this review includes the analysis of complex mixtures of disinfection byproducts (DBPs) and polybrominated diphenyl ether (PBDE) flame retardants. HILIC is a new LC technique that provides improved separation 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. An example of the use of HILIC in this review includes the measurement of veterinary pharmaceuticals in agricultural runoff waters.
[b]Online Analysis.[/b] There is also a trend toward more online analysis of contaminants. For example, there is a new multiresidue method reported for measuring antibiotics, using online SPE-LC/MS/MS. The use of online preconcentration-LC/MS/MS usually not only allows for more rapid screening but improves the precision of the analysis.
[b]Detection Limits.[/b] New analytical methods continue to push detection limits lower. Just a few years ago, microgram per liter detection limits were common. Today, it is unusual to see detection limits that are not at least low-nanogram per liter. There are even some examples in this review of picogram per liter detection limits. As instruments and extraction techniques continue to improve and new types of instruments are developed, detection limits will likely continue to drop, allowing the detection of analytes not previously possible. Another advantage of lower detection limits is in the study of transformation processes. For example, the study of wastewater treatment to remove pharmaceuticals is greatly aided by a technique that can measure low- or subnanogram per liter detection limits. Pharmaceuticals are generally present at nanogram per liter to low-microgram per liter levels in wastewater influents, and detection limits at the low- or subnanogram per liter level allow the percentage removal to be determined. Low detection limits also benefit human exposure studies, where amounts of biological samples are generally limited (microliter to milliliter).v$u i A lxL ~4v j
[b]Emerging Contaminants.[/b] Three new classes of emerging contaminants are added to this environmental mass spectrometry review this year: nanomaterials, 1,4-dioxane, and swimming pool DBPs. Nanomaterials are probably the hottest topic in research today. They are already being used in a variety of commercial products (particularly cosmetics), and there is significant concern about their potential human and ecological effects. Nanomaterials are the focus of a new initiative at the U.S. Environmental Protection Agency (EPA), where research on their fate, transport, and health effects is being investigated. Nanomaterials research in environmental samples is in its infancy, but there are now a few published studies, and this area is expected to grow exponentially in the next few years. 1,4-Dioxane is a widespread contaminant in groundwater and is a probable human carcinogen. Dioxane is a high production chemical and is used as a solvent stabilizer in the manufacture and processing of paper, cotton, textile products, automotive coolants, cosmetics, and shampoos. The U.S. EPA has recently listed dioxane on the new (3rd) proposed Contaminants Candidate List (CCL-3) ([url=http://www.epa.gov/safewater/ccl/ccl3.html#ccl3][color=#0066cc]www.epa.gov/safewater/ccl/ccl3.html#ccl3[/color][/url]). The CCL is a list of priority, unregulated contaminants that the U.S. EPA is considering for regulation. This list is used to prioritize research and data collection efforts to help in deciding whether to regulate a contaminant. Finally, swimming pool DBPs have become a hot research topic, as epidemiologic research has shown increased incidence of asthma with exposure in indoor pools and also increased incidence of bladder cancer. Because swimming pools have additional precursors (including components of human sweat, urine, sunscreens, etc.) for the formation of DBPs with chlorine or other pool disinfectants, unique byproducts can be formed.!c1e8kW2` h:nS
Other areas covered in this review again include perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and other perfluorinated compounds (PFCs), pharmaceuticals, hormones, EDCs, drinking water DBPs, sunscreens/UV filters, brominated flame retardants (including polybrominated diphenyl ethers), benzotriazoles, naphthenic acids, chiral contaminants, algal toxins, perchlorate, pesticide degradation products and new pesticides, and arsenic. These continue to be intense areas of research. A trend for these ongoing research areas is the study of their transformation in drinking water or wastewater treatment. For example, the chlorination and ozonation of pharmaceuticals, personal care products, and pesticides are represented in this review, as researchers try to find ways to remove these contaminants from source waters. However, new research is discovering that most of these compounds are not completely mineralized but are transformed into other compounds that may be less toxic or more toxic than the parent compounds. The reaction of ozone with nanomaterials is also reported in this review. Other fate studies include the study of the microbial degradation, hydrolysis, and photolysis of emerging contaminants, as well as the measurement of in vivo metabolites in human exposure studies. DW,}1la N g ^/v
I continue to be fascinated by the creative human exposure studies that are conducted. There is a huge growth in the number of human exposure studies conducted in the last 2 years. For example, PFCs were measured in more than 2000 human serum samples as part of the U.S. National Health and Nutrition Examination Survey, and they were also measured in the serum of retired fluorochemical production workers to investigate their half-lives in the human body. The toxicokinetics of a UV filter (4-methylbenzylidene camphor, 4-MBC) was investigated by measuring it in human plasma and urine after dermal application (simulating sunscreen exposure). PBDE flame retardants, which are now being found in biological samples all over the world, were measured in serum from residents living in an electronics dismantling region in China, as well as in human milk samples from women in Australia. Perchlorate has been measured in amniotic fluid from pregnant women in the United States. Trihalomethane DBPs were measured in the blood and breath of people carrying out common household water use activities. Algal toxins (microcystins) were measured in stored human tissues from a lethal poisoning episode in Brazil, where hemodialysis patients were exposed through tap water contamination.&Z\4AP1F4]S-O
Finally, one of the most comprehensive studies of an emerging contaminant (perchlorate) in foods and beverages is discussed in this review. In this study, >350 foods and beverages that were produced or harvested in more than 50 countries were analyzed for perchlorate. Most foods had measurable levels, some with high microgram per kilogram levels, revealing that perchlorate contamination is not limited to the United States but is a worldwide phenomenom. Foods and beverages analyzed included fresh and canned fruits and vegtables, baby foods, wine, beer, tea, milk, and fruit juices.
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ASAP [i]Anal. Chem.,[/i] [b]ASAP Article[/b], 10.1021/ac800660d
[b]Web Release Date:[/b] May 23, 2008 好东西！ 感谢楼上的 呵呵
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