Hatzinger, P., J.K. Boehlke, N.C. Sturchio, and B. Gu.
Environmental Security Technology Certification Program (ESTCP), Project ER-200509, 107 pp, Dec 2011

This report primarily describes the sampling and analysis methods that have been developed and are now used routinely for measuring Cl and O isotope ratios in perchlorate. It identifies initial recommendations for appropriate QA/QC protocols. This document, along with the growing published, peer-reviewed literature on Cl and O isotopic analyses of perchlorate, discusses the application of the method and summarizes the data generated by the method to date. The main approach described in this document, chlorine and oxygen isotopic analysis of perchlorate, yields accurate and precise measurements of the relative abundances of the stable isotopes of chlorine (Cl-37 and Cl-35) and oxygen (O-18, O-17, and O-16) in perchlorate using isotope-ratio mass spectrometry (IRMS). It also can yield the relative abundance of the radioactive chlorine isotope Cl-36 using accelerator mass spectrometry. Altogether, these measurements provide four independent quantities (isotope abundance ratios) for distinguishing perchlorate sources and potential transformations in the environment. Other isotopic, chemical, and geochemical techniques that can be applied in conjunction with isotopic analyses of perchlorate to provide supporting data also are described. Methods used for Cl and O isotopic analyses of perchlorate are presented to provide background on this general approach, and current isotopic data for perchlorate are described as well. A case study illustrates the application of IRMS of Cl and O stable isotopes to distinguish sources of perchlorate on Long Island, New York. http://www.serdp-estcp.org/content/download/13045/153500/file/ER-200509-GD.pdf