Hydrogen fuel cell technologies rely on ultra-pure hydrogen for efficient and reliable operation. Even trace impurities like CO, H₂S, and NH₃ can significantly impact the performance and longevity of fuel cells. The paper discusses recent advancements in hydrogen fuel quality assurance, focusing on the importance of maintaining strict purity standards set by the ISO. Innovations include gravimetrically prepared gas standards, compact chromatography instruments, and advanced sensors like quartz-enhanced photoacoustic sensors. Various sensing technologies such as Optical Feedback Cavity Enhanced Absorption Spectroscopy, photoacoustic spectroscopy, mass spectrometry, and gas chromatography are employed to detect impurities at sub ppb levels. Different sampling protocols, including gas parallel and serial methods, help ensure accurate measurements without contamination. High-quality reference materials are crucial for calibrating testing instruments and comparing results across different laboratories. Despite the challenges in synthesizing commercial reference materials that meet ISO standards, advancements in this area are vital for the safe and effective scaling of hydrogen infrastructure globally.