SPE in US EPA Method 625, the Performance of Smaller Samples

Oral Presentation

Prepared by Z. Grosser1, B. Prakash2, W. Lipps2, T. Ogura2, M. Ebitson1, A. Cannon1
1 - Horizon Technology, Inc., 16 Northwestern Dr, Salem, NH, 03079, United States
2 - Shimadzu Scientific Instruments, Inc, 7102 Riverwood Drive, Columbia, MD, 21046, United States

Contact Information: zgrosser@horizontechinc.com; 603-386-3654


US EPA method 625 is a general semivolatile method for wastewater analysis applied to a large suite of target analytes. Although method 625 was developed a number of years ago, through the EPA Office of Water, Office of Science and Technology, the method has been updated several times and a new revision has been released with the Method Update Rule, proposed in February 2015. As new technology is developed either for the determinative measurement or, earlier in the analysis process, for the sample preparation, data must be collected to demonstrate that the new technology is compliant and reproducible.

This study focusses on the use of 100-mL water samples rather than larger samples often used to achieve the sensitivity needed for compliance results. The smaller samples may be faster to prepare and easier to handle, providing a number of benefits to the laboratory and client.

This paper will discuss the performance of SPE in general for method 625 and the specific performance of a disk used with a single pass of acidified water through it rather than a pass with basified water and a second pass with the same water, now acidified, which is typical for liquid-liquid extraction. Recoveries of a large suite of compounds from a variety of matrices and laboratories will be examined and the effect of surrogates will be considered. The implications of larger and smaller sample volumes for overall costs, analytical performance and handling will be discussed.