Revision History for Techniques and Methods 10-C17 Tyler B. Coplen, Haiping Qi, Kinga Révész, Karen Casciotti, and Janet E. Hannon Determination of the delta-15N and delta-18O of Nitrate in Water; RSIL Lab Code 2900 ----------------------------------------------------- First posted 2007, ver. 1.0 ----------------------------------------------------- Revised and reposted September 17, 2012, ver. 1.1 "delta-(15N/14N)" was replaced by "delta-15N" and "delta-(18O/16o)" was replaced by "delta-18O" in the title to be in accordance with recommendations of the Commission on Isotopic Abundances and Atomic Weights of the International Union of Pure and Applied Chemistry. Tyler B. Coplen, Haiping, Qi, and Janet E. Hannon were added as coauthors. "Summary of Procedure" and "Labware, Instrumentation, and Reagents" sections were updated to reflect improved method of Coplen and others (2004) and new instrumentation. "Reporting Units and Operational Range" section was updated to reflect expression of delta values with number ratios. "Reference Materials and Documentation" and "Health, Safety, and Water-Disposal Information" sections were updated to reflect improved method of Coplen and others (2004). "Sample Collection, Preparation, Analysis, Retention Times, and Disposal" and "Data Acquisition, Processing, Evaluation, Quality Control, and Quality Assurance" sections were updated to reflect improved method of Coplen and others (2004) and to reflect that samples are no longer submitted through the National Water Quality Laboratory (NWQL). Four references were added to the "References Cited" section. Appendixes A and H were updated to reflect that samples are no longer submitted through the National Water Quality Laboratory (NWQL). Appendixes B and C were updated to reflect improved method of Coplen and others (2004). Main text footer was removed from the document.