The James Hutton Institute has state of the art instrumentation capable of carrying out isotopic analysis on many different sample types, such as rocks, soils, plant materials, gases and waters.

Principal contacts for Isotopic Analysis:

• Barry Thornton
• Carol-Ann Craig
• Sheila Gibbs

Light stable isotopes

We currently have five isotope ratio mass spectrometers connected to a wide range of peripheral equipment allowing us to measures the isotopes of carbon (C), nitrogen (N) and oxygen (O) in a wide range of samples. For example we determine so called “bulk” C, N and O isotopes (i.e. isotopes of the whole material) in solids such as plant material, soils and marine sediments (hydrogen isotopes are under development). We are capable of determining the C isotopes of dissolved inorganic C in both fresh and saline waters and C isotopes of dissolved organic C in fresh waters. Additionally we determine C and O isotopes of carbon dioxide in gaseous materials.

We are also capable of compound specific analysis of neutral and phospholipid fatty acids (C isotopes), alkanes (C isotopes) and amino acids (C and N isotopes); these analyses have many applications in biological science. We also have extensive preparation facilities and experience of extracting these compounds from samples..

Contact: Barry Thornton

Inorganic isotopes

    We have the capacity to perform high precision isotope ratio analysis of a range of non-gaseous isotope systems from Boron to Uranium including Calcium, Magnesium, Potassium, Strontium, Neodymium, Samarium and Lead.

These analysis are carried out using Thermal Ionisation Mass Spectrometry – TIMS. At the institute we have two TIMS instruments; a VG Sector 54 TIMS and as of 2017 a new Isotopix Phoenix TIMS. This state-of-the-art new instrument is capable of analysing trace level samples with the highest sensitivity producing high precision, high quality data.

Isotopes are a powerful tool and those analysed by our TIMS have previously been used in many applications such as dating (directly and indirectly) rocks; and provenancing materials such as sediments, waters, pollutants, crops and other food stuffs.

We also have the facilities to prepare (including HF digestion) and purify samples prior to analysis including our new automated ion-exchange column system (prepFAST). We are also very willing to develop new methods as required.

Water isotopes

Many catchment-specific hydrological processes modify the initial isotopic (?²H, ?¹⁸O) signature of precipitation and its temporal variations: such as terrestrial flow path characteristics and transit times; interactions between ground and surface water; hydrological mixing processes; confluence with tributaries; evaporation from lakes; climatic changes and anthropogenic influences such as reservoirs or irrigation (Kendall et al., 2001; Rank et al., 2009).

Isotopic signatures of ?²H and ?¹⁸O in ground, loch and river water are indicators for these hydrological processes within catchments, for example, ?²H and ?¹⁸O of rivers “reflect how the relative amounts of precipitation and groundwater change with time and how the isotopic compositions of these sources themselves change over time” (Kendall et al., 2001). Isotopic signatures of river water act as a spatio-temporal integrator of the variable isotopic composition of precipitation across its drainage area.

The Liquid Water Stable Isotope Analyser measures ¹⁸O and ²H which contributes to the understanding of catchment hydrological functions.

Contact: Sheila Gibbs

ICP-MS (Agilent 7700)

The Agilent 7700 Inductively Coupled Plasma – Mass Spectrometer (ICP-MS) is one of the most advanced and smallest of its kind in the world.

Principle

Aqueous samples are made into a fine mist by a peristaltic pump feeding a nebulizer attached to a spray chamber. The mist is entrained into a stream of Argon gas and passed through an Argon plasma where molecules and broken into atoms which are in turn ionised. The ions are streamlined into the ion optics and separated by a mass filter onto an Ion detector. The isotopes of the different elements are determined by their mass/charge ratio.

Benefits of the ICP-MS over the ICP-OES

The ICP-MS can detect elements at typically three to four orders of magnitude better that an ICP-OES. It can also differentiate between isotopes of elements allowing isotopic ratios to be analysed.

What do we use it for?

Waters and acid digested soils for typically up to 20 elements. This instrument is capable of analysing nearly two thirds of the periodic table and unlike most ICP-MSs is capable of handling high matrix samples, such as undiluted seawater due to its high matrix introduction system where the analyte stream is diluted with extra Argon.

Contact: Fiona Sturgeon