Horizon Technology Participation in the ILI SPE US EPA Method 625 Study

Oral Presentation

Prepared by Z. Grosser, W. Jones, M. Ebitson, D. Gallagher, A. Cannon
Horizon Technology, Inc., 16 Northwestern Drive, Salem, NH, 03079, United States


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


ABSTRACT

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. 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.

Two small round-robin studies using multiple vendor products and solid phase extraction (SPE) materials in a variety of laboratories have been run to demonstrate the compliance of SPE with method requirements. The first study relied on the quality control in the existing method to catch when the equipment or sorbent did not work properly. In the second study, the choice of surrogates was enlarged to ensure that errors not caught with the criteria in the older version of 625 would be identified in this version.

This paper will discuss the performance of SPE method 625 using a disk 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 results from the first round robin demonstrated recoveries from 70-130% of most all the acid/base/neutral/pesticides chosen for the study using a multi-mode disk adsorbent. These results will be compared to results from the second study and comparisons of large and small volumes of sample, different surrogate mixes and interlaboratory performance for the Horizon Technology products will be discussed.