抄録
One of the most powerful techniques in the molecular isotope studies is compound-specific isotope analysis (CSIA) by gas chromatograph/isotope ratio mass spectrometer (GC/IRMS), which allows a rapid and precise determination of stable carbon, nitrogen, and hydrogen (and oxygen) isotopic compositions of individual compounds even in complex mixture of components. After commercial production of GC/IRMS in the 1990s, CSIA has explosively been used for many fields of studies, particularly among the organic geochemical community as a powerful tool for tracing sources and delivery of organic compounds in geological and geographical samples and for reconstructing paleoenvironments. However, it is also true that fundamental analytical parameters of GC/IRMS has not been known extensively, which often leads to unreliable determination of the isotopic compositions. Unfortunately, based on such unreliable determination, several studies have unconsciously reported essentially inaccurate data and associated discussion. Therefore, in this paper, we review a brief outline of GC/IRMS and associated methodologies, and summarize the instrumental factors influencing accuracy and precision of the isotope measurements. We hope that this paper is useful for applying CSIA to future studies.
