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 analyzing 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. This results in more refined answers to research questions, that cannot always be effectively addressed with bulk isotope analysis alone.

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 and animal migration
δ13C fatty acids sediment provenance and tracking
δ13C amino acids food web structure, dietary sources, amino acid synthesis
δ2H amino acids bacterial metabolism
δ2H fatty acids palaeoclimate studies


NIWA specializes 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 are continually developing novel analytical techniques 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 derivatized to make them suitable for GC analysis. Following separation of compounds on the GC, samples 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 derivatization can also be provided by NIWA. Please enquire about your specific sample requirements to the contacts below.


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


Dr Brittany Graham
Ph +64 4 386 0516