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EPA Method 544: A Case Study in USEPA Drinking Water Method Develpment
Citation:
Shoemaker, J., Dan Tettenhorst, AND A. Delacruz. EPA Method 544: A Case Study in USEPA Drinking Water Method Develpment. International Algal Toxin Conference, Akron, OH, May 09 - 11, 2016.
Impact/Purpose:
The impact of this presentation is to make the algal toxin community aware of EPA Method 544 for the analysis of microcystins and what is involved in the development of EPA drinking water methods.
Description:
The 1996 amendments to the Safe Drinking Water Act required the U.S. Environmental Protection Agency (USEPA) to establish a Drinking Water Contaminant Candidate List (CCL) of chemicals and microbes that the Agency will consider for future regulation. One of the key pieces of information that must be available in order to make a regulatory determination is nationwide occurrence data for the chemical contaminants under consideration. Historically, USEPA’s Office of Ground Water and Drinking Water has collected the necessary occurrence data under its Unregulated Contaminant Monitoring Regulations (UCMR). Thus, standardized and rugged methods that will produce data of sufficient quality for UCMR monitoring of chemicals and microbes on the CCL are needed. It is important that these standardized methods are accurate, precise and sensitive, as well as transferrable to laboratories participating in the UCMR. The key steps in EPA’s drinking water analytical method development process are 1) literature review, 2) instrumentation selection, 3) extraction optimization if necessary, 4) preservation selection, 5) testing in challenging drinking water matrices, 6) lowest concentration minimum reporting level determination, 7) sample holding time determination and 8) multi-laboratory verification. Typical data quality objectives (DQOs) are 70-130% recovery (accuracy) of the analyte from the water sample and <30% relative standard deviation (precision). This presentation will describe each of these steps in greater detail by illustrating the development of EPA Method 544 for the analysis of microcystins and nodularin. Method 544 was developed in response to microcystin-LR being listed on the third CCL (2009).
