Our services
The Stable Light Isotope Lab makes analytical facilities available to researchers for the measurement of stable isotope ratios of light elements (C, N, O, H and S) in a range of materials.
We are equipped to analyse organic samples such as dried plant material, animal tissues such as hair, bone collagen, feathers, flesh, also organics collected on filter papers and in soils. Filter papers and soils require additional steps, so they typically take longer to analyse and are therefore more expensive.
We also analyse carbonates in geological samples and in biominerals such as tooth enamel, ostrich eggshell, and foraminifera.
Less frequently, we measure hydrogen, and triple oxygen isotopes, as well as silicate oxygen.
We are an academic research lab so we encourage students to visit the lab and learn how their samples will be analysed, or where possible, analyse them themselves, with supervision. This will require discussion with your supervisor and laboratory personnel.
Please enquire with us before sending samples. Although we try our best to keep up with demand, we generally have a 3–4-month turnaround time. At very busy times, this may be longer.
IRMS capabilities.
The Stable Light Isotope Lab makes available analytical facilities for the measurement of C, N, O and in some cases H (S coming soon!) isotopes on different types of sample materials. We use state-of-the-art equipment operated by highly skilled technicians who can help guide your analyses.
Our equipment includes three light isotope ratio mass spectrometers (IRMS), as well as an infrared direct absorption spectrometer (TILDAS, Aerodyne, Inc). The IRMS instruments are interfaced with elemental analysers and other peripherals such as gas benches for automated sampling of carbonates and some types of gaseous samples.
At present our instruments are set up as follows, though this is subject to change.
2010 Delta V+ is set up to analyse C & N in organic samples for example plant material, bone collagen, organics in soils and those collected on filter papers.
2020 Delta V+ as above, but can also analyse S in materials such as hair and bone collagen.
Samples are weighed into tin cups using a microbalance. For protein materials, we typically weigh 0.3-0.4 mg for measurement of both δ¹³C and δ¹⁵N.The cups are folded to exclude air, then combusted in a Flash 2000 series elemental analyser (Thermo Finnigan). The gases are passed to a Delta Plus V+ IRMS (isotope ratio mass spectrometer) (Thermo Finnigan), via a Conflo IV gas control unit (Thermo Finnigan, Bremen, Germany). The reproducibility of repeated measurements of homogeneous materials is typically ≤ 0.2‰ for both δ¹³C and δ¹⁵N.
Delta + XP is set up to analyse C & O in carbonates in materials such as tooth enamel, ostrich eggshell and geological carbonates. The instrument is also run in dual inlet mode to measure C, O and D/H in silicates and waters prepared offline in the Department of Geological Sciences.
The sample requirements are different for different analytes, so please contact us about your proposed study. Samples are weighed into 12ml borosilicate tubes closed with screw top lids containing a septum. For pure carbonates, we require in the region of 0.2mg of samples while for materials such as tooth enamel, we require 2mg.
Tunable infrared laser direct absorption spectrometer (TILDAS, Aerodyne, Inc) is used for high precision measurement of δ¹³C and triple oxygen isotopes (δ¹³C, δ¹⁸O, δ¹⁷O or “Δ¹⁷O”) of CO₂. This is interfaced with a carbonate digestion device for geological carbonates, and biominerals. This instrument can also measure atmospheric CO₂ at ~415 ppm (2021). This is the only such instrument on the African continent, and one of only a handful of facilities worldwide capable of performing such high precision measurements.