The Collaborative Efforts to Develop an EPA Method for 6PPD-Q in Aqueous Matrices

Innovative Solutions for Water Testing
Oral Presentation

Prepared by A. Hanley1, B. Pepich2, H. McCarty3, A. Patterson1, B. Mitzel1, G. Dodo1
1 - USEPA OST, 1200 Pennsylvania Avenue NW, Washington, DC, 20460, United States
2 - USEPA Region 10, 7411 Beach Drive East, Port Orchard, WA, 98366, United States
3 - General Dynamics Information Technology, 3170 Fairview Park Drive, Falls Church, VA, 23310, United States


Contact Information: [email protected]; 202-564-1564

ABSTRACT

A December 2020 publication by the University of Washington reported that p-phenylenediamine (PPD), an antiozonant added to tires for more than six decades, is being converted by ozone to 2-anilo-5-[(4-methylpentan-2-yl)amino]cyclohexa-2,5-diene-1,4-dione (6PPD-Q), a quinone that has been found in stormwaters and Pacific NW rivers after rainfall events at concentrations toxic to Coho salmon. Early in 2021, Region 10 EPA convened a monthly roundtable of federal, state and tribal scientists to share information on this contaminant. The group expressed a strong need for an EPA method for this contaminant in surface and storm waters. EPA initiated a collaborative effort with Eurofins-Sacramento to conduct a single-laboratory validation study of an existing Eurofins LC-MS/MS method that utilized SPE and isotope dilution quantitation. Region 10 worked with the EPA Office of Water to develop a Quality Assurance Project Plan for the single-laboratory validation study with sufficient rigor to support development of a formal EPA 1600-Series method.

On January 30, 2024, in what the Region 10 Administrator termed “lightspeed,” EPA delivered Draft Method 1634, an LC-MS/MS procedure that includes data from the single-laboratory study that demonstrate that 6PPD-Q can be reliably measured in surface water and stormwater at approximately
2 ng/L, well below the 95 ng/L LC50 for Coho. Testing of wastewater samples is underway and other matrices are under consideration. Publication of the draft method will promote a more consistent approach to future analysis of 6PPD-Q and provide tribes and local governments with an important tool for better understanding stormwater and surface water quality. This project also demonstrates EPA’s commitment to respond to emerging contaminant needs in relatively short order. EPA’s Office of Water will assess whether to pursue a multi-laboratory study in the future.