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Hydrogen is expected to be a new power and heat source to
reduce greenhouse gases. Hydrogen is an easily available
substance that can be produced from the electrolysis of water in
our daily lives. However, when used in fuel cells, it is necessary to
control impurities in hydrogen gas because certain impurities
introduced during the manufacturing process deteriorate the
electrode and electrolyte membrane, reducing the performance
of the fuel cell or shortening its life. This section presents an
example of analysis of inorganic halogens, formic acid, ammonia,
and formaldehyde in hydrogen based on the standard values
described in ISO 14687 Grade D
1)
.
Introduction
This analysis meets the standard values of ISO14687 Grade D.
Simultaneous analysis of inorganic halogens and formic acid is possible.
Since organic solvents are not used for extraction during pretreatment, environmental impact is reduced.
Analysis of Inorganic Halogens, Formic Acid,
Ammonia, and Formaldehyde as Impurities in Fuel
Cell Grade Hydrogen Based on ISO14687 Grade D
Hiroyuki Aikawa, Jiang Yujing, Ayano Tanabe
Ion Chromatograph, High Performance Liquid Chromatograph
ISO14687 Grade D specifies impurities in hydrogen that affect the
quality of fuel cell vehicles. Table 1 lists the applicable ingredients,
standard values, concentrations (μg/L) converted by ion
chromatograph (IC) / high-performance liquid chromatograph
(HPLC), and equipment used.
Hydrogen Impurity Specifications in
ISO14687 Grade D
Ingredients of interest
Specified
value
(μmol/mol)
IC/HPLC
Converted
concentration
(μg/L)
Equipment used
Inorganic halogen (hydrogen chloride)
*1
0.05 28
Suppressor IC
Formic acid
*2
0.2 92
Ammonia 0.1 26 Non-suppressor IC
Formaldehyde 0.2 141 HPLC
Table 1 Substances and specifications in ISO14687 Grade D
*1 The value of hydrogen chloride is shown as a representative value.
*2 Deleted in the 2025 edition
A suppressor IC (Fig. 1, left) was used for inorganic halogen
analysis. Since IC can selectively measure ions in a sample, it is less
affected by contaminants than other methods, and inorganic
halogens can be measured with high accuracy. Three
components were simultaneously measured: chloride ion (Cl) as
hydrochloric acid, bromide ion (Br) as hydrogen bromide, and
formic acid (HCOOH). Table 2 shows the analytical conditions. Fig.
2 shows the chromatogram of each 50 μg/L standard sample. Fig.
3 and Table 3 show the calibration curves for the concentration
range of 25 μg/L to 1000 μg/L. As shown in Fig. 3 and Table 3, the
linearity was greater than 0.9999 in all cases. Table 4 shows the
repeatability for 7 replicates at concentrations near the lower limit
of quantification.
Analysis of Inorganic Halogens, Formic Acid,
and Ammonia by IC
Fig. 1 Equipment used
Suppressor IC (HIC-ESP) Non-suppressor IC (HIC-NS) HPLC(Nexera lite)
System : HIC-ESP
Column : Shim-pack IC-SA2 (250 mm
×
4.0 mm I.D., 9 µm)
*1
Guard Column : Shim-pack IC-SA2(G) (10 mm
×
4.6 mm I.D., 9 µm)
*2
Mobile Phase : 12 mM NaHCO3 + 0.6 mM Na2CO3
Flow Rate : 0.8 mL/min
Column Temp. : 30 ˚C
Injection Vol. : 100 μL
Vial : 4 mL, Polypropylene
*3
Detection : Conductivity
Table 2 Analysis conditions (inorganic halogens)
Fig. 2 Chromatogram of inorganic halogens (50 μg/L each)
Fig. 3 Calibration curves for inorganic halogens
0.0 5.0 10.0 min
0
1.0
µS/cm
HCOOH
Br
Cl
0 250 500 750
Concentration
(μg/L)
0
5000
10000
15000
20000
25000
30000
Area
0 250 500 750
Concentration
(μg/L)
0
10000
20000
30000
40000
50000
60000
70000
Area
r
2
= 0.99998
Formic acid Chloride ion
r
2
= 0.99994
r
2
= 0.99995
Bromide ion
0 250 500 750
Concentration
(μg/L)
0
5000
10000
15000
20000
25000
30000
Area
*1 P/N : 228-38983-91, *2 P/N : 228-38983-92, *3 P/N : 228-31537-91
Conc. of
Calibration
Curves µg/L
Peak Area
of Formic
acid
Peak Area
of Chloride
ion
Peak Area
of Bromide
ion
STD1 20 487 1267 501
STD2 50 1373 3192 1392
STD3 100 2822 6449 2831
STD4 500 15410 32837 14289
STD5 1000 31127 66830 29066
correlation coefficient
(r
2
)
0.99998 0.99994 0.99995
Table 3 Concentration of calibration curves and peak area
for inorganic halogens
