GB/T 44242-2024Hydrogen for proton exchange membrane fuel cell vehicles - Determination of inorganic halides and formic acid - Ion chromatography (English PDF)

1 Scope

GB/T 44242-2024 specifies the determination of inorganic halides and formic acid in the hydrogen used by fuel cell vehicles, by ion chromatography. Halides are among the most damaging impurities in the fuel: chloride attacks the catalyst and corrodes the bipolar plates and the effect is cumulative and irreversible, which is why the limit is set at a few parts per billion. Formic acid is limited for the same reason. Measuring either at that level in a gas means trapping it out of a large, precisely known volume of hydrogen into a small volume of water and then analysing that, and the standard covers the whole chain: the principle, the reagents and materials, the apparatus and the absorption system, the sampling and the volume measurement, the preparation of the standard solutions, the chromatographic conditions and the suppression, the calibration, the analytical procedure, the calculation back to a concentration in the gas, the precision and the limit of quantification. For a hydrogen supplier or a testing laboratory in China, this is the prescribed method.

This document describes the principle, reagents and materials, instruments and equipment, test procedures, test data processing, precision, quality assurance and control, and test report for the determination of inorganic halogenated compounds and formic acid in hydrogen for proton exchange membrane fuel cell vehicles by ion chromatography. This document is applicable to the determination of inorganic halogenated compounds and formic acid in hydrogen for proton exchange membrane fuel cell vehicles. The determination of inorganic halogenated compounds and formic acid in hydrogen for other purposes shall be carried out in reference. The determination range of inorganic halogenated compounds and formic acid in hydrogen is 0.025 µmol/mol~0.5 µmol/mol. The detection limits of hydrogen chloride, chlorine, hydrogen bromide and formic acid components in hydrogen are 0.014 µmol/mol, 0.007 µmol/mol, 0.002 µmol/mol and 0.001 µmol/mol, respectively. NOTE. Inorganic halogenated compounds in this document refer to hydrogen chloride, chlorine and hydrogen bromide which may be present in hydrogen gas.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 629, Chemical reagent. Sodium hydroxide

GB/T 637, Chemical reagent -- Sodium thiosulfate pentahydrate

GB/T 639, Chemical reagent -- Sodium carbonate anhydrous

GB/T 640, Chemical reagent -- Sodium hydrogen carbonate

GB/T 6682, Water for analytical laboratory use -- Specification and test methods

GB/T 14666, Terms for analytical chemistry

GB/T 43306, Gas analysis -- Sampling guidelines

GB/T 44262, Technical requirements for sampling of hydrogen for proton exchange membrane fuel cell vehicles

JJF 1342, General Requirements for the Competence of Reference Material Producers JJG 823, Ion Chromatographs

3 Terms and definitions

For the purposes of this document, the terms and definitions defined in GB/T 14666 apply.

4 Principle

Inorganic halogenated compounds and formic acid in the hydrogen sample are absorbed by the alkaline solution to generate halide ions and formate ions. They are separated by anion chromatography column and detected by conductivity detector. They are qualitatively determined by retention time and quantitatively determined by calibration curve.

5 Reagents and materials

5.1 Test water It shall comply with the requirements of GB/T 6682 for Grade 1 reagent water.

7 Test procedures

7.1 Sampling The sampling of hydrogen for proton exchange membrane fuel cells shall comply with Prepare calibration samples suitable for testing the content of inorganic halogenated compounds in hydrogen not greater than 0.07 µmol/mol and the content of formic acid not greater than 0.05 µmol/mol. Pipette 1 mL of the chloride stock solution (5.3.1), bromide stock solution (5.3.2) and formic acid stock solution (5.3.3). Place them in a 100 mL volumetric flask. Add water to the set volume and mix well to obtain a mixed solution with a target ion mass concentration of 10 mg/L. Pipette 0 mL, 2 mL, 4 mL, 6 mL, 8 mL, and 10 mL of the above mixed solutions respectively. Place them in a group of 100 mL volumetric flasks. Add water to the set volume and mix well to obtain calibration samples with theoretical mass concentrations of 0 mg/L,

0.2 mg/L,

0.4 mg/L,

0.6 mg/L,

0.8 mg/L, and

1.0 mg/L, respectively.

7.2.5 Preparation of blank samples Take an impact absorption bottle from the same batch containing 10 mL of absorption liquid. Disconnect it from the gas source. Shake well for testing.

7.3 Instrument preparation Optimize the ion chromatography operating conditions and eluent elution procedure according to the composition of the sample to be tested, the instrument model and configuration. See Table A.1 in Annex A for typical ion chromatography operating conditions. See Table A.2 for typical eluent elution procedures.

7.4 Establishment of calibration curve Inject the calibration samples from low concentration to high concentration in sequence. Draw the calibration curve with the mass concentration (mg/L) of the target ion as the horizontal axis and the peak height or peak area as the vertical axis. The typical chromatogram of the target ion is shown in Figure A.1.The calibration curve of the target ion is shown in Figure A.2.The calibration curve shall be linear, with R2 >= 0.999.

7.5 Blank determination Inject the blank sample into the ion chromatograph. Determine the content of the target ions under the same chromatographic conditions as those used to draw the calibration curve. The measured values of the three target ions in the blank sample shall all be lower than

0.1 mg/L.