We developed an analytical method attaining SI-traceability for various volatile organic compounds using only one calibration material (reference material). An apparatus was designed and made in which analytes are converted to methane for detection. Test sample gases were prepared by the precise gravimetric method and used for the evaluation of our analytical method. The results showed that the analytes in the sample gases were converted to methane stoichiometrically and the analytical values showed good consistency to the gravimetric values.