Prior to stable isotope ratio measurements different samples has to be brought in gaseous form. A host of preparation methods have been developed and improved to convert different sample compounds to an appropriate gas including H₂, CO, CO₂, N₂, and SO₂. The measured values expressed in delta notation like δ²H, δ¹³C, δ¹⁵N, δ¹⁸O, δ³⁴S The delta values are defined as follows: δ (‰) = (R_sample/ R_reference-1) * 1000, where R is the ¹³C/¹²C, ¹⁵N/¹⁴N or ³⁴S/³²S etc. ratio in the sample or in the international reference. The isotope results were calculated on the basis of the known values of international standard materials.

The Elemental Analyser (Fisons NA1500 NCS) is based on the complete and instantaneous oxidation of the sample by flash combustion which converts all organic and inorganic substances into combustion products. The resulting combustion gases pass through a reduction furnace and are swept into the chromatographic column by the carrier gas (helium). The gases are separated in the column and detected by the IRMS (δ¹³C, δ¹⁵N, δ³⁴S). Isotopic analyses of water samples or carbonates are carried out with an automated GASBENCH II sample preparation device attached to the IRMS. Hydrogen and oxygen isotopes of the water, carbon and oxygen isotopes of carbonate samples are measured by this method. The high temperature conversion elemental analyser (TC/EA) coupled to the IRMS is suitable to determine the δ²H and δ¹⁸O values of solid samples and of fluid samples as well.