Spectrometer DELTA V Series/MAT 253, Thermofisher Scientific (IRMS)

A system is used for the analysis of stable isotopes of elements important in the physiology of plants and animals, i.e. C, N, S, O, and H. This makes it possible to trace the place of origin of a plant/tree, trace the migration of animals, or estimate the climatic conditions in the past based on the representation of oxygen isotopes in individual annual rings. The device has the potential to generate practical outputs as well, as it is possible to verify the origin of wood on the market based on stable isotopes. The IRMS set consists of the following components (all by Thermo Fisher Scientific):

• EA IsoLink IRMS Elemental analyzer

The elemental analyzer quantitatively converts the H, C, N, O, or S contained in a sample into gaseous substances (typically H2, CO2, N2, CO, SO2). It comprises two furnaces, one for high-temperature conversion of O and H, and the other is used for N, C, and S combustion in the presence of oxygen. Produced gases are further led into the GC column, which performs chromatographic separation of the reaction products generated during the combustion or high-temperature conversion process. Gas flow composition is determined by a thermal conductivity detector (TCD) and is further transferred to the mass spectrometer for isotope analysis.

• ConFlo IV universal interface

To dose a gas sample into MS under standardized conditions, a ConFlo IV universal interface for online continuous flow preparation system is used. This comprises the system for sample dilution with He, dosing reference gases, switching the gas flow off and on, and providing uniform gas pressure at the MS inlet. This is achieved using a series of calibrated capillary connections and two open-split tubes.

• DELTA V Plus mass spectrometer

The isotope ratio mass spectrometer (IRMS) consists of five main components: a gas inlet, a source with an ionization chamber, ion optics, a magnetic separator, and collection cups. Gas samples enter the mass spectrometer through an inlet and, once in the source, the sample gas molecules are converted into ions by electron impact ionization. The ions are then concentrated and accelerated towards a static magnetic field in a direction perpendicular to its intensity vector. This curves their flight path based on their atomic mass to charge ratio. Lighter ions are deflected more than heavier ones. Different ions hit dedicated collecting cups, where they generate an electrical signal proportional to the number of incident ions. The integrated signals from each collection cup are then used to calculate the isotopic ratio and the delta value.

Location: Eco-physiological laboratory with IRMS (stable isotopes) L047