Citation:

Batt, A., E. Furlong, H. Mash, S. Glassmeyer, AND D. Kolpin. The importance of quality control in validating concentrations of contaminants of emerging concern in source and treated drinking water samples. Presented at SETAC North America, Vancouver, CANADA, November 09 - 13, 2014.

Impact/Purpose:

This abstract will be submitted for a poster presentation at the 2014 SETAC North America Meeting in Vancouver, CA. The poster will describe the results of an inter-methods comparison study of the analytical tools used to measure 44 emerging chemical contaminants measured in drinking water. Update November 3, 2014 - The abstract was accepted, and the package has been updated to include the poster presentation as well.

Description:

A national scale survey of 251 chemical contaminants in source and finished drinking water was conducted at 25 drinking water treatment plants across the U.S. To address the necessity of using multiple methods in determining a broad array of CECs, we designed a quality assurance/quality control program which allowed us to assess and compare the relative performance of the methods used. Of the 251 contaminants measured, 44 compounds were determined in two or more different methods, and are representative of several classes of pharmaceuticals, personal care products, steroids, hormones, and antimicrobials. This results of this study include: data from a combination of ambient environmental and fortified matrix spike samples, three independent laboratories conducting six analytical methods, and results from the broadest array of water types collected and preserved under a nationally consistent protocol. Every sample was collected in triplicate. The first was analyzed as a primary sample, the second as a duplicate to monitor intra method reproducibility, and the third was used as a matrix spike to monitor matrix enhancement or suppression. Laboratory and field blanks were also analyzed to monitor possible sample contamination. Overall method performance was first assessed by comparing spiked recoveries in distilled water, source water, and treated water over a two year period of time. Of the 44 compounds included in the methods comparison, 22 were detected in either the source or finished drinking water. In general, the results between the methods displayed good agreement. Carbamazepine was measured in four different methods, and displayed excellent agreement in both quantitative frequency of detection (28% in source and 8% in finished water) and measured concentrations (up to 57 ng/L). The biggest influence in differences in frequency of detection among the remaining analytes was a result of the varying detection limits between the technologies applied. In addition to the 251 chemical contaminants included in the survey, there were another 48 compounds measured that did not consistently meet predetermined quality standards and environmental data was not reported for these compounds. An overview of which methodology did not seem suitable for these analytes is included, and the need to exclude these analytes based on overall method performance demonstrates the importance of the additional QA/QC protocols.

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