Water analysis: emerging contaminants and current issues.

This biennial review covers developments in water analysis over the period of 2003-2004. A few significant references that appeared between January and February 2005 are also included. Analytical Chemistry’s current policy is to limit reviews to include 100-200 significant references and to mainly focus on new trends. As a result, as was done in the previous 2003 water analysis review (1), this 2005 review will limit its focus 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. We would welcome any comments you have, in particular regarding this more narrow focusswhether you find it more (or less) useful than a broader approach ([email protected]). Numerous abstracts were consulted before choosing the best ones to present here. Abstract searches were carried out using the 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 websites is also provided (Table 2). The overall trends in analytical methods for water analysis include an increased use of solid-phase microextraction (SPME), the use of newly developed solid-phase extraction (SPE) sorbents for improved extraction, and an increased use of other reduced solvent extraction methods, such as the recently developed singledrop microextraction (SDME) method and stir bar sorptive extraction method. SDME involves the suspension a small drop of extraction solvent directly from the tip of a microsyringe into the vial containing the water sample, where the target analyte is extracted into the drop, and the drop is retracted back into the needle and injected directly into the injection port of a gas chromatograph. Examples of this presented in this review include the analysis of methyl-tert-butyl ether (MTBE) and chemical warfare agents. Stir bar sorptive extraction involves the use of a sorbent-coated stir bar, which is stirred in the aqueous sample to extract the analyte of interest. The analyte is then thermally desorbed and analyzed by gas chromatography (GC)/mass spectrometry (MS). Examples of this presented in this review include the analysis of phenolic xenoestrogens and organotins. New derivatization methods continue to be developed, including the development of fluorinated chloroformate derivatizing agents to enable the GC/MS identification of highly polar polyalcohol, amine, and carboxylic acid disinfection byproducts in drinking water. There also seems to be an increase in the use of in situ derivatization for the GC/MS analysis of aqueous samples. The fluorinated chloroformate derivatization is an example of this, along with the use of in situ acetylation, which is also presented in this review. For detection methods, the use of liquid chromatography (LC)/MS has now become common place for analyzing many emerging contaminants, including pharmaceuticals, hormones, and endocrine disrupting compounds (EDCs), in aqueous environmental samples. The use of LC/MS allows the identification of highly polar organic pollutants without derivatization, down to nanogram per liter levels in aqueous samples, including surface water, wastewater, groundwater, and drinking water. To gain enhanced selectivity and sensitivity, tandem-MS is increasingly being used with LC/MS for the measurement of environmental contaminants in water. Drawbacks of LC/MS include matrix effects (e.g., ion suppression, which can vary with varying environmental matrix composition) and difficulty in separating highly polar analytes in the aqueous LC eluent. Increasingly, researchers are developing techniques to overcome these drawbackssfor example, through the use of deuterated or 13Clabeled internal standards to overcome matrix effects, and the use of ion-pair reagents or hydrophilic interaction chromatography (HILIC) to allow highly polar analytes to elute away from the LC solvent front. † U.S. Environmental Protection Agency. ‡ Federal Institute of Hydrology. Anal. Chem. 2005, 77, 3807-3838