A preconcentration system attached to a GC/C/MS (gas chromatography/combustion/mass spectrometer) was developed to determine the carbon-isotope composition of methane in volcanic gases with extremely low concentration. With this system, we can analyze the carbon isotope ratio ( 13 C/ 12 ) of 0.7 - 6 nmol methane with a precision of ± 1.6‰, unlike other conventional methods without preconcentration (150 - 1000 nmol CH 4 with a precision of ± 0.2‰). This system was tested with volcanic gas samples from Satsuma-Iwojima volcano, suggesting a mixture of magmatic and thermogenic origins for methane.
All Science Journal Classification (ASJC) codes
- Analytical Chemistry