Some consumer goods containing radioactive substances are in circulation and used in everyday life. In accordance with the Nuclear Safety Act, consumer goods with radioactivity are regulated. However, since most consumer goods distributed in Korea have no information that can confirm the amount of radiation, it is necessary to analyze the radiation for safety regulation. Among these consumer goods, GTLS (Gaseous Tritium Light Source) contains gaseous tritium (tritium, written as 3H or T), which is a radioactive material. The gaseous composition ratio in GTLS was analyzed using a precision gas mass spectrometer (Thermo Fisher, model MAT 271). As a result of GTLS analysis, the H2, HD or H3 +(T) or 3He, HT or D2 or He, DT, and T2, which correspond to the mass-to-charge ratio (m/z) 2 to 6 and the air components were detected. In addition, substances corresponding to m/z=24 and m/z=21 were also detected. These were compared with pure CH4 and those fragmentation patterns. The ratios of CT4 (m/z = 24) to CT3 (m/z = 21) and CH4 (m/z = 16) to CH3 (m/z = 15) were compared and they agree within the measurement uncertainty. We also performed additional experiments to separate the water component in the GTLS samples, considering the possibility that the m/z = 21 to m/z = 24 region is tritium compounds based on H2O. Despite the removal of the water components, peaks were detected at m/z=21 and m/z=24. Therefore, we confirmed that the component of m/z = 24 in the GTLS sample was CT4.