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

## TL;DR

This study evaluates the stability of gas mixtures used to test hydrogen purity, finding that some compounds remain stable for months while others degrade.

## Contribution

The study demonstrates the feasibility of using multicomponent gas standards for hydrogen purity analysis under ISO 14687 Grade D.

## Key findings

- Several inert and semireactive species remain stable in hydrogen matrices for over 6 months.
- Ammonia stabilizes after a 60-day equilibration period, but oxygen shows inconsistent behavior.
- Formaldehyde and formic acid show complete signal loss, indicating poor stability.

## Abstract

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.