A system for determining isotopic composition of a gaseous sample. The system includes at least one gas chromatograph for separating the gaseous sample into gaseous components. Furthermore, the system includes a combustion furnace operatively coupled with the at least one gas chromatograph for oxidizing the gaseous components. Moreover, the system includes a water separator operatively coupled with the combustion furnace. Furthermore, the system includes an isotope-ratio mass spectrometer operatively coupled with the water separator. Moreover, the isotope-ratio mass spectrometer comprises an ion source for generating ion beams associated with each of the oxidized gaseous components and a mass analyser for receiving the generated ion beams from the ion source, wherein the mass analyser is operable to determine isotopic concentrations associated with each of the ion beams. Furthermore, the isotope-ratio mass spectrometer is operable to use the determined isotopic concentrations to determine the isotopic composition of the gaseous sample.