Logo Universitat Bremen
Die Inhalte dieser Seite sind leider nicht auf Deutsch verfügbar.

Mass Spectrometry on Inorganic Samples


The Stable Isotope Laboratory is the central facility at MARUM for analyzing stable oxygen and carbon isotopes on carbonates, and carbon isotopes on water (dissolved inorganic carbon, DIC). One of the carbonate systems is currently modified for measuring Clumped Isotopes
Analytical capacity is available to employees of MARUM and the Department of Geosciences at the University of Bremen. Employees from other Departments may contact us for information.
For conventional stable isotope measurements, the laboratory operates as a service facility, i.e., users have access to the analytical capacity, but (usually) not the laboratory proper. Samples provided by the users are measured by the laboratory staff. Contact us for details on preparing, documenting and submitting samples. Also check our
Clumped Isotope measurements require the detailed understanding of the analytical procedures and data evaluation by the user. With guidance by the laboratory staff, users will carry out most of the analytical work by themselves. See


Isotope ratios are not directly measured on elemental carbon and oxygen, but inferred from measuring isotopologues of CO2. Signal intensities of mass-to-charge ratios 44, 45 and 46 reflect the abundances of 12C16O16O, 13C16O16O and 12C18O16O. δ13C is calculated from the intensity ratios of masses 45:44, and δ18O from 46:44.

Measurements are calibrated against (1) a reference gas of known isotopic composition (volcanic CO2 for carbonates, industrial CO2 for water), and (2) a carbonate standard of known composition. The carbonate standard is ground and sieved Solnhofen limestone (calcite), itself calibrated against NBS 19. For every 36 samples, 9-10 carbonate standards are measured.


Dr. Henning Kuhnert


+49 421 218-65520


+49 421 218-65505



MARUM I, 1150

Liquid nitrogen tank and mass spectrometers


Three mass spectrometers (Finnigan MAT 251, Finnigan MAT 252, ThermoFisher 253plus) are coupled to automated carbonate preparation ("Kiel") devices. Typical samples include foraminifera, corals, and bulk sediment. For marine samples, the oxygen isotopic composition is an indicator of the past ocean hydrography (temperature, salinity), while carbon isotopes reflect nutrients and ocean water mass distributions.

In the automated carbonate preparation device the sample is dissolved with phosphoric acid, and the generated CO2 gas is purified and transferred to the mass spectrometer. 

The mass spectrometer is equipped with a dual inlet system, where for each sample the pressure of the reference gas is adapted to the pressure of the sample gas. This procedure reduces non-linearities of the spectrometer and hence analytical uncertainty.

Each carbonate device has a throughput of 36 samples per day (plus 9-10 standards). The combined annual throughput is approximately 14,000 samples.

Details on costs, submitting samples and general procedures are found in the Guidelines and Terms of Use ("Nutzerordnung").

Sample tray and acid valves of the carbonate device

Filling of the sample tray

Clumped Isotopes in Carbonates

One system (an additional ThermoFisher 253plus with Kiel IV) is modified for measuring clumped isotopes (Δ47). The hardware is based on that for conventional carbonate measurements (see above), but the mass spectrometer is equipped with additional detectors, and the carbonate preparation device incorporates an additional cold trap for removing hydrocarbons.

The abundance of the rare CO2 isotopologue 13C18O16O (mass 47) is, in theory, a function of the abundances of 13C and 18O. However, measured δ47 differs from the predicted value, because 13C and 18O are not stochastically distributed between the different CO2 isotopologues, but tend to "clump" together. This deviation (Δ47) is temperature-dependent. 

The advantage of Δ47 is the independence from the isotopic composition of the ambient water during carbonate formation - in paleoceanographic terms, Δ47 is a temperature proxy that is not biased by δ18Owater.

The standard error on a single Δ47 measurement roughly translates to a temperature uncertainty of ±7.5 °C. Such precision is usually insufficient for palaeoceanographic applications, but can be significantly improved by measuring multiple replicates. With 20-30 replicates the uncertainty is reduced to ~ ±1.5 °C. This, of course, requires a relatively large amount (2 to 3 mg of CaCO3) of sample material.

Measurements of clumped isotopes are currently in the experimental phase. We are not yet accepting regular samples.

See Guidelines and Terms of Use ("Nutzerordnung").



A Gasbench II coupled to a Finnigan MAT 252 mass spectrometer is used to determine the carbon isotope composition of the DIC of water samples, typically seawater and sediment pore water. In seawater, δ13C of DIC reflects primary productivity in surface waters, and the degradation of organic matter in deep waters.

Phosphoric acid is added to the sample, forcing all species of dissolved inorganic carbon (CO2, HCO3-, CO32-, and undissociated H2CO3) to degas as CO2. The latter is then transferred to the mass spectrometer.

Daily throughput is 48 samples (plus 12 standards).

Details on costs, submitting samples and general procedures are found in the Guidelines and Terms of Use ("Nutzerordnung").



Bevern, Wolfgang+49 421 218-65528MARUM 1360[Bitte aktivieren Sie Javascript]
Kuhnert, Henning, Dr.+49 421 218-65520MARUM I, 1150[Bitte aktivieren Sie Javascript]
Meyer-Schack, Birgit+49 421 218-65524MARUM I, 1190[Bitte aktivieren Sie Javascript]
Steinkamp, Maike+49 421 218-65547MARUM I, 1190[Bitte aktivieren Sie Javascript]