Compound specific isotope analysis of individual amino acids (CSI-AA) is a powerful tool for tracing nitrogen (N) source and transformation in biogeochemical cycles. Specifically, the delta15N value of phenylalanine (delta15N Phe) represents an increasingly used proxy for baseline delta15N values, with particular promise for paleoceanographic applications. Further, multiple studies have shown that delta15N values of Phe and glutamic acid (Glu) can be coupled to provide precise estimates of trophic position (TP), while simultaneously decoupling baseline delta15N values from the effects of trophic transfer. However, current derivatization/gas chromatography (GC) methods require expensive and relatively uncommon instrumentation, and have relatively low precision, posing significant issues for many potential applications. Here we present a new approach to CSI-AA based on a high-pressure liquid chromatography (HPLC) purification of underivatized amino acids, followed by offline elemental analysis-isotope ratio mass spectrometry (EA-IRMS). The utility of this approach is demonstrated in two different applications using natural materials: 1) the construction of a high precision paleoceanographic record from the delta15NPhe in proteinaceous coral tissue and 2) the TP estimation of five marine organisms using the coupled delta15N values of Glu and Phe. Both demonstrations were compared to values measured by an established GC based method. In all cases both methods produced equivalent values, however, values generated by the new HPLC/EA-IRMS approach had higher average precision in all cases. These results demonstrate that this approach represents a viable alternative to traditional GC based methods for delta15NAA measurement and may therefore allow significant expansion of CSI-AA applications, requiring only commonly available instrumentation to produce high precision delta15N AA values.

The use of Compound-specific Stable Isotope Analysis (CSIA) is increasing in many areas of science and technology for source allocation, authentication, and characterization of transformation reactions. Until now, there have been no textbooks available for students with an analytical chemical background or basic introductory books emphasising the instrumentation and theory. This book is the first to focus solely on stable isotope analysis of individual compounds in sometimes complex mixtures. It acts as both a lecture companion for students and a consultant for advanced scientists in fields including forensic and environmental science. The book starts with a brief history of the field before going on to explain stable isotopes from scratch. The different ways to express isotope abundances are introduced together with isotope effects and isotopic fractionation. A detailed account of the required technical equipment and general procedures for CSIA is provided. This includes sections on derivatization and the use of microextraction techniques in GC-IRMS. The very important topic of referencing and calibration in CSIA is clearly described. This differs from approaches used in quantitative analysis and is often difficult for the newcomer to comprehend. Examples of successful applications of CSIA in food authenticity, forensics, archaeology, doping control, environmental science, and extraterrestrial materials are included. Applications in isotope data treatment and presentation are also discussed and emphasis is placed on the general conclusions that can be drawn from the uses of CSIA. Further instrumental developments in the field are highlighted and selected experiments are introduced that may act as a basis for a short practical course at graduate level.

Tracking Animal Migration with Stable Isotopes, Second Edition, provides a complete introduction to new and powerful isotopic tools and applications that track animal migration, reviewing where isotope tracers fit in the modern toolbox of tracking methods. The book provides background information on a broad range of migration scenarios in terrestrial and aquatic systems and summarizes the most cutting-edge developments in the field that are revolutionizing the way migrant individuals and populations are assigned to their true origins. It allows undergraduates, graduate students and non-specialist scientists to adopt and apply isotopes to migration research, and also serves as a useful reference for scientists. The new edition thoroughly updates the information available to the reader on current applications of this technique and provides new tools for the isotopic assignment of individuals to origins, including geostatistical multi-isotope approaches and the ways in which researchers can combine isotopes with routine data in a Bayesian framework to provide best estimates of animal origins. Four new chapters include contributions on applications to the movements of terrestrial mammals, with particular emphasis on how aspects of animal physiology can influence stable isotope values. Includes an animal physiology component that is an in-depth overview of the cautions and caveats related to this technique Covers marine and aquatic isoscapes and methods to track marine organisms for researchers trying to apply isotopic tracking to animals in these environments Features state-of-the-art statistical treatments for assignment and combining diverse datasets

This book highlights new and emerging uses of stable isotope analysis in a variety of ecological disciplines. While the use of natural abundance isotopes in ecological research is now relatively standard, new techniques and ways of interpreting patterns are developing rapidly. The second edition of this book provides a thorough, up-to-date examination of these methods of research. As part of the Ecological Methods and Concepts series which provides the latest information on experimental techniques in ecology, this book looks at a wide range of techniques that use natural abundance isotopes to: follow whole ecosystem element cycling understand processes of soil organic matter formation follow the movement of water in whole watersheds understand the effects of pollution in both terrestrial and aquatic environments study extreme systems such as hydrothermal vents follow migrating organisms In each case, the book explains the background to the methodology, looks at the underlying principles and assumptions, and outlines the potential limitations and pitfalls. Stable Isotopes in Ecology and Environmental Science is an ideal resource for both ecologists who are new to isotopic analysis, and more experienced isotope ecologists interested in innovative techniques and pioneering new uses.

The 20th century has experienced environmental changes that appear to be unprecedented in their rate and magnitude during the Earth’s history. For the first time, Stable Isotopes as Indicators of Ecological Change brings together a wide range of perspectives and data that speak directly to the issues of ecological change using stable isotope tracers. The information presented originates from a range of biological and geochemical sources and from research fields within biological, climatological and physical disciplines covering time-scales from days to centuries. Unlike any other reference, editors discuss where isotope data can detect, record, trace and help to interpret environmental change. Provides researchers with groundbreaking data on how to predict the terrestrial ecosystems response to the ongoing rapid alterations Reveals how ecosystems have responded to environmental and biotic fluctuations in the past Includes examples from research by a wide range of biological and physical scientists who are using isotopic records to both detect and interpret environmental change

This book is the first laboratory manual to bring together basic procedures for measurement of stable and radioactive isotopes of nitrogen, with specific applications to plant, soil, and aquatic biology. This bench-top reference gives practical coverage of mass and emission spectrometry, nitrogen fixation, nitrification, and identification, organic nitrogen, and the radioactive isotope 13N. Methods are described so that researchers can adapt them, without the aid of outside references, to virtually any task they may encounter in investigations of nitrogen transformation processes. Serves as a practical guide for nitrogen isotope techniques Features studies of nitrogen transformations in terrestrial and aquatic systems Includes basic measurement techniques plus specific applications for stable and radioactive nitrogen isotopes Presents detailed protocols, overviews, and key references Includes fifty figures and sixteen tables Hands-on reference for both students and researchers

Section 3. Method development: 21. Ultra-sensitive elemental analyzer/isotope ratio mass spectrometer for stable nitrogen and carbon isotope analyses / Ogawa, N.O. ... [et al.] -- 22. An improved method for precise determination of carbon isotopic composition of amino acids / Chikaraishi, Y. and Ohkouchi, N. -- 23. Instrumental optimization of compound-specific nitrogen isotope analysis of amino acids by gas chromatography/combustion/isotope ratio mass spectrometry / Chikaraishi, Y. ... [et al.] -- 24. Enantiomer-specific isotope analysis of D-and L-alanine / Takano, Y., Chikaraishi, Y. and Ohkouchi, N. -- Appendix. Summary of methods for measuring isotopic compositions presented in this book / Ohkouchi, N., Tayasu, I., and Koba, K.