Multicomponent Gas Standards for Hydrogen Purity Analysis According to ISO 14687 Grade D

ISO 14687 sets strict impurity limits for hydrogen used across a wide range of applications, including fuel cell road vehicles (Grade D). Ensuring compliance with these thresholds requires precise analytical methods and certified gas standards for each regulated contaminant. However, preparing and maintaining individual reference standards for routine analysis is resource-intensive. To support the use of multicomponent standards in hydrogen purity control, this study examines the time-dependent stability of commercially prepared standards of ISO 14687 Grade D contaminants in hydrogen matrices. Using ion-molecule reaction, electron-impact mass spectrometry, along with Fourier-transform infrared spectroscopy, results show that several inert and semireactive species, including helium, argon, methane, propane, carbon dioxide, carbon monoxide, carbonyl sulfide, and halogenated compounds, remain stable for over 6 months. Ammonia concentrations stabilized after a 60-day equilibration period of the gas mixture, while oxygen showed inconsistent behavior. Formaldehyde and formic acid exhibited complete signal loss, indicating poor stability in multicomponent mixtures. These findings support the development of reliable multicomponent gas standards and strengthen hydrogen quality control practices under ISO 14687.