ASTM D7550-09

Low operating temperature fuel cells such as proton exchange membrane (PEM) fuel cells require high purity hydrogen for maximum material performance and lifetime. Analysis to part-per-billion (ppb) concentration of individual cation contaminants such as potassium, sodium and ammonium in hydrogen and related fuel cell supply gases is necessary for assuring a feed gas of sufficient purity to satisfy fuel cell system needs. More specifically, cations such as ammonium causes irreversible performance degradation of proton exchange membranes used in low temperature fuel cells by reacting with protons in the membrane to form ammonium ions.

Although not intended for application to gases other than hydrogen and related fuel cell supply gases, techniques within this test method can be applied to other gaseous samples requiring cation analysis.

1.1 This test method describes a procedure for the determination of cations in hydrogen and other fuel cell feed gases. It has been successfully applied to other types of gaseous samples including air, engine exhaust, and landfill samples. An ion chromatograph/conductivity detector (IC/CD) system is used to determine cations. Sensitivity from low part per billion (ppb, μg/l, μg/kg) up to part per million (ppm, mg/l, mg/kg) concentration are achievable dependant on the amount of hydrogen or other fuel cell gas sampled. This test method can be applied to other gaseous samples requiring analysis of trace constituents provided an assessment of potential interferences has been accomplished.

1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.