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Compound Specific Isotope Analysis (CSIA)

Compound specific stable isotope analysis techniques are an increasingly useful tool to address many ecological and environmental research questions. By analysing the stable isotope composition of specific compounds, researchers can probe more deeply into the fundamental processes responsible for environmental or ecological change at the molecular level to community levels.

This results in more refined answers to research questions and information for ecosystem and environmental management and conservation, that cannot always be effectively addressed with bulk isotope analysis alone. In addition, the CSIA approach has been applied successfully to terrestrial, coastal and oceanic ecosystems for a diverse range of scientific inquiries.

Trace GC Ultra and GC Isolink, plus GC-PAL autosampler for compound specific isotope analysis (CSIA). [Photo: Dave Allen, NIWA]

Sample types:
organic samples, e.g. animal and plant tissue, sediment/soil

Research applications:

δ15N amino acids trophic ecology, animal migration, detailed food web structure, regime & primary production shifts, historical animal trophic ecology and food web reconstruction
δ13C fatty acids sediment provenance and tracking, marine animal tracking and fidelity (coastal), bacteria and primary producer metabolism, carbon cycling in terrestrial, coastal, and marine ecosystems
δ13C amino acids food web structure, dietary sources, amino acid synthesis
δ2H amino acids bacterial metabolism
δ2H fatty acids palaeoclimate reconstruction


NIWA specialises in the investigation of oceanic trophic ecology and animal migration using the δ15N values of individual amino acids. More recently, we have developed a method for carbon isotope analysis of fatty acids for tracing sediment sources following the techniques of Gibbs (2008). We have further developed this approach to be applied to marine food web reconstruction and sourcing marine animal origins in nearshore, coastal environments. We are continually developing novel analytical techniques and application in response to individual research needs and encourage early contact to discuss potential research opportunities.

CSIA is conducted using gas chromatography isotope ratio mass spectrometry (GC-IRMS). Samples for CSIA are isolated and purified from bulk material (i.e. tissue, feathers, collagen, plant material, etc.) and then derivatised to make them suitable for GC analysis. We employ several methods to prepare the individual compounds for analysis, and all of these chemical procedures have been developed and optimized at NIWA laboratories. Following separation of compounds on the GC, the compounds are combusted in a furnace before gases are introduced into the IRMS. NIWA’s Stable Isotope Analytical Facility houses a Thermo Fisher Scientific (Bremen, Germany) Trace GC Ultra, coupled with a GC-Isolink connected to a Delta V IRMS via a Conflo IV open split.

Currently, NIWA offers δ15N and δ13C analysis of amino acids and δ13C analysis of fatty acids (see table at top of page for more info). Sample processing and derivatisation can also be provided by NIWA. Please enquire about your specific sample requirements to the contact below.

Key references

Fatty Acids SIA methods and science

Gibbs, M. (2008). Identifying source soils in estuarine sediments: a new compound specific isotope method. Estuaries and Coasts, 31, 344-359.

Thorp, J. R. Bowes (2017). Carbon sources in riverine food webs: new evidence from amino acid isotope techniques. Ecosystems, 20, 1029-1041.

Amino Acids SIA methods and science

Popp, B., B. Graham, R. Olson, C. Hannides, M. Lott, G. Lopez-Ibarra, and F. Galvan-Magana (2007) Insights into the trophic ecology of yellowfin tuna, Thunnus albacares, from compound-specific nitrogen isotope analysis of proteinaceaous amino acids. In T. Dawson and R. Seigwolf [eds.], Isotopes as Indicators of Ecological Change. Elsevier. Pp 173-190.

Lorrain, A., Graham, B.S., Popp, B.N., Allain, V., Olson, R.J., Hunt, B.P.V., Potier, M., Fry, B., Galván-Magaña, F., Menkes, C., Kaehler, S., and F. Menard (2013). Nitrogen isotopic baselines and implications for estimating foraging habitat and trophic position of yellowfin tuna in the Indian and Pacific Oceans. Deep-Sea Research, DOI10.1016/j.dsr2.2014.02.003i

Ohkouchi, N., Y. Chikaraishi, H. Close, B. Fry, T. Larsen, et al. (13 additional co-authors) (2017). Advances in the application of amino acid nitrogen isotopic analysis in ecological and biogeochemical studies. Organic Chemistry, 113, 150-174.

Larsen, T., M. Ventura, N. Andersen, D. O’Brien, U. Piatkowski (2013). Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting. PLoS One 8, e73441.

trophic ecology, animal migration, detailed food web structure, regime & primary production shifts, historical animal trophic ecology and food web reconstruction


Principal Scientist - Marine Biogeochemistry