2This article discusses developments in environmental analytical chemistry that occurred in the years of 2003 and 2004. References were found by searching the Science Citation Index and Current Contents. As in our review of two years ago (A1), techniques are highlighted that represent current trends and state-of-the-art technologies in the sampling, extraction, separation, and detection of trace concentrations, low-part-perbillion and less, of organic, inorganic, and organometallic contaminants in environmental samples. New analytes of interest are also reviewed, the detections of which are made possible by recently developed analytical instruments and methods.In our review of two years ago, we discussed developments in analytical techniques published in [2001][2002] in the context of analysis trends that have occurred over the past decade in the areas of sample collection and extraction, separation and detection, and analytes of emerging environmental interest. We highlighted techniques and methods that best demonstrated the evolution of environmental analysis. In this review, we explore a narrower historical perspective. Beginning with the focus areas that were identified in our last review, we re-examine these areas and emphasize recent contributions to their development. Although there is a trend towards making measurements of environmental contaminants in the field with portable instruments, we have restricted the scope of our review to cover only laboratory-based techniques.Because all method development work starts with information learned from previous studies, we first discuss information collection strategies. In the area of sample collection and extraction, we highlight developments in semi-permeable membrane devices, solid-phase microextraction, hollow fiber, liquid-phase microextraction, and new materials for solid phase extraction. In our discussion of important separation and Carolyn Koester, 03-25-2005 3 detection techniques, we mention developments in novel chromatographic stationary phases, chiral separations, two-dimensional gas chromatography, time-of-flight mass spectrometry, and inductively coupled plasma mass spectrometry, including its use for isotope measurements, its coupling with chromatographic separations techniques, and its use with laser ablation, and nuclear magnetic resonance spectroscopy. As emerging detection techniques, we highlight accelerator mass spectrometry and high-field asymmetric waveform ion mobility spectrometry. As in our last review, we have also tabulated a list of contaminants of current concern and the analytical strategies that are used for their detection in environmental media.Because the requirements of the editors necessitate that we be selective in our review, we acknowledge that we will not be able to mention all of the noteworthy developments in the analysis of trace pollutants present in environmental matrices that have occurred since 2003. For this reason, we encourage our readers to examine the other articles published in the 2005 Application Revie...
The potential for aerobic methyl tert-butyl ether (MTBE) degradation was investigated with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygenlimited in situ conditions. MTBE depletion was observed for sediments from two sites (e.g., 4.5 mg/liter degraded in 15 days after a 4-day lag period), whereas no consumption of MTBE was observed for sediments from the other sites after 75 days. For sediments in which MTBE was consumed, 43 to 54% of added [U-14 C]MTBE was mineralized to 14 CO 2 . Molecular phylogenetic analyses of these sediments indicated the enrichment of species closely related to a known MTBE-degrading bacterium, strain PM1. At only one site, the presence of water-soluble gasoline components significantly inhibited MTBE degradation and led to a more pronounced accumulation of the metabolite tert-butyl alcohol. Overall, these results suggest that the effects of oxygen and water-soluble gasoline components on in situ MTBE degradation will vary from site to site and that phylogenetic analysis may be a promising predictor of MTBE biodegradation potential.The magnitude and remediation cost of methyl tert-butyl ether (MTBE) contamination in drinking water have rapidly become a national concern. It has been estimated that 250,000 of the approximately 385,000 confirmed leaking underground storage tank (LUST) releases in the United States involve MTBE (15). In California, at least 10,000 LUST sites are estimated to be contaminated with MTBE (13). Several states, including California, have set primary maximum concentration levels for MTBE at or below 20 g/liter, and at an even lower level of 12 g/liter for tert-butyl alcohol (TBA), an MTBE metabolite. The U.S. Environmental Protection Agency has listed MTBE as a possible human carcinogen, whereas TBA is a known animal carcinogen (7). MTBE appears to be more mobile and less biodegradable than BTEX compounds (benzene, toluene, ethylbenzene, and xylenes), and consequently, MTBE plumes have extended over kilometer-scale distances, as is the case at Port Hueneme, Calif., and East Patchogue, N.Y.Previous microcosm studies reported little or no biodegradation of MTBE under a variety of aerobic (11,14) and anaerobic (18,23,26) conditions. More recent microcosm (3) and column (6) studies suggest that limited intrinsic biodegradation of MTBE may occur. One research group observed MTBE mineralization activity in stream-bed sediments from both contaminated and pristine sites under aerobic conditions (4,5). Mixed cultures capable of MTBE degradation have been isolated from activated sludge (10,20). Pure bacterial cultures capable of MTBE metabolism have been reported (12,17,22), including strain PM1, which uses MTBE as a sole carbon source and electron donor (12), and propane-oxidizing strains that cometabolize MTBE (22). In microcosm and field experiments, Salanitro et al. (21) showed that oxygenation in combination with bioaugmentation with an MTBE-degrading consortium resulted in more rapid MTBE degradation, alt...
An electrospray ionization mass spectrometry/mass spectrometry (ESI/MS/MS) method was developed to measure part-per-billion (µg/L) concentrations of perchlorate in groundwater. Selective and sensitive perchlorate detection was achieved by operating the mass spectrometer in the negative ionization mode and by using MS/MS to monitor the ClO 4to ClO 3transition. The method of standard additions was used to address the considerable signal suppression caused by anions that are typically present in groundwater, such as bicarbonate and sulfate. ESI/MS/ MS analysis was rapid, accurate, reproducible, and provided a detection limit of 0.5 µg/L perchlorate in groundwater. Accuracy and precision of the ESI/MS/MS method were assessed by analyzing performance evaluation samples in a groundwater matrix (4.5-75 µg/L perchlorate) and by comparing ion chromatography (IC) and ESI/MS/ MS results for local groundwater samples (<0.5-35 µg/L perchlorate). Results for the performance evaluation samples differed from the certified values by 4-13%, and precision ranged from 3 to 10% (relative standard deviation). The IC and ESI/MS/MS results were statistically indistinguishable (P > 0.05) for perchlorate concentrations above the detection limits of both methods.
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