ASTM D7649-10

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D7649 − 10
Standard Test Method for
Determination of Trace Carbon Dioxide, Argon, Nitrogen,
Oxygen and Water in Hydrogen Fuel by Jet Pulse Injection
and Gas Chromatography/Mass Spectrometer Analysis
This standard is issued under the fixed designation D7649; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 constituent—A component (or compound) found
within a hydrogen fuel mixture.
1.1 Thistestmethoddescribesaprocedureprimarilyforthe
3.1.3 contaminant—impuritythatadverselyaffectsthecom-
determination of carbon dioxide, argon, nitrogen, oxygen and
ponents within the fuel cell system or the hydrogen storage
water in high pressure fuel cell grade hydrogen by gas
system by reacting with its components.An adverse effect can
chromatograph/mass spectrometer (GC/MS) with injection of
be reversible or irreversible.
sample at the same pressure as sample without pressure
reduction,whichiscalled“JetPulseInjection”.Theprocedures
3.1.4 dynamic calibration—calibration of an analytical sys-
described in this method were designed to measure carbon
temusingcalibrationgasstandardgeneratedbydilutingknown
dioxide at 0.5micromole per mole (ppmv), Argon 1 ppmv,
concentration compressed gas standards with hydrogen, as
nitrogen 5 ppmv and oxygen 2 ppmv and water 4 ppmv.
used in this method for carbon dioxide, argon, nitrogen and
oxygen (7.3 and 7.4).
1.2 The values stated in SI units are standard. The values
stated in inch-pound units are for information only.
3.1.5 extracted ion chromatogram (EIC)—a GC/MS chro-
matogram where a selected ion is plotted to determine the
1.3 The mention of trade names in standard does not
compound(s) of interest.
constitute endorsement or recommendation for use. Other
manufacturersofequipmentorequipmentmodelscanbeused. 3.1.6 fuel cell grade hydrogen—hydrogen satisfying the
specifications in SAE TIR J2719.
1.4 This standard does not purport to address all of the
3.1.7 hydrogen fuel—hydrogen to be tested without compo-
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- sitional change due to sample introduction, etc.
priate safety and health practices and determine the applica-
3.1.8 jet pulse injection—high pressure hydrogen fuel
bility of regulatory limitations prior to use.
sample is introduced instantaneously at the same pressure into
GC/MS.
2. Referenced Documents
3.1.9 relative humidity—ratio of actual pressure of existing
2.1 Other Standards:
water vapor to maximum possible pressure of water vapor in
SAE TIR J2719Information Report on the Development of
the atmosphere at the same temperature, expressed as a
aHydrogenQualityGuidelineforFuelCellVehiclesApril
percentage.
3.1.10 response factor (RF)—-theamountinvolume(µL)of
3. Terminology
an analyte divided by the EIC area of the analyte.
3.1 Definitions of Terms Specific to This Standard: 3.1.11 static calibration—calibration of an analytical sys-
3.1.1 absolute pressure—pressure measured with reference tem using standards in a matrix, state or manner different than
to absolute zero pressure, usually expressed as kPa, mm Hg, the samples to be analyzed, as used in this method for water
bar or psi. All the pressures mentioned in this method are concentration in hydrogen.
absolute pressure.
3.2 Acronyms:
3.2.1 FCV—fuel cell vehicle.
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
3.2.2 PEMFC—proton exchange membrane fuel cell.
Fuels and is the direct responsibility of Subcommittee D03.14 on Hydrogen and
Fuel Cells.
CurrenteditionapprovedDec.1,2010.PublishedFebruary2011.DOI:10.1520/ 4. Summary of Test Method
D7649–10.
4.1 The simultaneous analysis of carbon dioxide, argon,
AvailablefromSAEInternational(SAE),400CommonwealthDr.,Warrendale,
PA 15096-0001, http://aerospace.sae.org. nitrogen, oxygen and water at 0.5 – 5 ppmv (micromole per
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7649 − 10
mole) in hydrogen fuel samples from fueling stations is 4.4 A mass spectrometer provides sensitive and selective
challenging due to high hydrogen fuel sample pressure and detection towards carbon dioxide, argon, nitrogen, oxygen and
possible contaminations from ambient air. water.
4.2 In this method, a small stainless steel loop is initially
5. Significance and Use
pressurized with high pressure hydrogen standard or sample
5.1 Low operating temperature fuel cells such as proton
without any pressure regulation or restriction (“Sample Loop
exchange membrane fuel cells (PEMFCs) require high purity
Pressurization”, Fig. 1). The hydrogen in the loop is then
hydrogen for maximum performance. The following are the
released entirely as a “jet pulse” into a T-union which splits
reported effects (SAE TIR J2719) of the compounds deter-
sample into a 0.25 µm ID 30 m long capillary column and an
mined by this test method.
electronic flow controller (EFC) used to vent excess hydrogen
to the atmosphere (“Jet Pulse Injection”, Fig. 2). Less than 1%
5.2 Carbon Dioxide (CO ), acts largely as a diluent, how-
of hydrogen enters the capillary column with the remaining
ever in the fuel cell environment CO can be transformed into
sample venting to atmosphere through EFC. As demonstrated
CO.
inAppendixX1,thehydrogenvolume“jetpulseinjected”into
5.3 Water (H O), is an inert impurity, as it does not affect
the capillary column is a constant volume and independent of
the function of a fuel cell stack; however, it provides a
thesamplelooppressurewhenthesamplelooppressureisover
transport mechanism for water-soluble contaminants, such as
90 psi. Therefore, the constant hydrogen volume from stan-
+ +
Na or K . In addition, it may form ice on valve internal
dards or samples is GC/MS analyzed in regardless of standard
surface at cold weather or react exothermally with metal
or sample pressures.
hydride used as hydrogen fuel storage.
4.3 Jet pulse injected volume into the capillary column is
5.4 Inert Gases (N and Ar), do not normally react with a
approximate 100 µL (In Appendix X1, this volume is calcu-
fuel cell components or fuel cell system and are considered
lated to be 115µL under the analytical conditions described in
diluents. Diluents can decrease fuel cell stack performance.
Appendix X1). When a 2-mL of sample loop is pressurized to
5.5 Oxygen (O ), in low concentrations is considered an
200 psi, the hydrogen in the loop is (200 psi/14.7psi)×2mL
inert impurity, as it does not adversely affect the function of a
or 27 mL. Hence, 99.5% of the hydrogen sample vents to
fuel cell stack; however, it is a safety concern for vehicle on
atmosphere. This type of “Jet Pulse Injection” has been found
board fuel storage as it can react violently with hydrogen to
acceptable for the analysis of high pressure hydrogen fuel
generate water and heat.
sample since the hydrogen volume injected is independent of
the pressures of hydrogen standards or samples. Consequently
6. Apparatus
itisunnecessarytoregulatestandardsandhydrogensamplesto
the same pressure. In addition to possible trace leaks or air 6.1 Mass Spectrometer (MS)—The MS can perform mass
trappedinside,regulatorsarenotrecommendedasmoistureon calibration with a scanning range from m/e 15 to 650. The
background peak intensities of water, nitrogen, argon, oxygen
the regulator surface can be released into the sample resulting
in a high moisture determination. and carbon dioxide in the mass spectrum of FC-43
FIG. 1 Sample Loop Pressurization
D7649 − 10
FIG. 2 Jet Pulsed Injection
(perfluorotributylamine), used for mass calibration, should be 6.3.3 Carrier Gas—Ultra high purity hydrogen is used as
less than 10% of m/e 69 to demonstrate a background carrier gas. Use of helium carrier gas results in unacceptable
acceptable for the determination of these analytes before broadening of the water chromatographic peak.An example of
beginning sample analysis. All analytes determined according water peaks is shown in Fig. 3.
to this method have a molecular mass less than 44 amu;
6.3.4 GC Injector—An injector port with a glass insert and
therefore, the mass scanning range of m/e 15 to 50 is typically
a septum is connected through a ⁄16 in. OD stainless steel
used.
tubing to a jet pulse split (6.4.5) in the inlet system (6.4). The
injector temperature is set to at 220°C to ensure that all water
6.2 Data System—Acomputer or other data recorder loaded
vapor in injected ambient air are not condensed in the injector.
with appropriate software for data acquisition, data reduction,
The GC column and total split flow rate are electronically set
and data reporting and possessing the following capabilities is
at 1.5 and 75 mL/min, respectively. The GC total split flow
required:
includes a GC septum purge flow of 3mL/min (Fig. 1 and Fig.
6.2.1 Graphic presentation of the total ion chromatogram
2) and GC injector split flow of 72mL/min.
(TIC) and extracted ion chromatogram (EIC).
6.2.2 Digital display of chromatographic peak areas.
6.4 Inlet System—A system introduces high pressure
6.2.3 Identification of peaks by retention time and mass
samples or standards into GC/MS for analysis. The sample or
spectra.
standard enter the inlet system through “Sample Loop Pressur-
6.2.4 Calculation and use of response factors.
ization” (Fig. 1) and then leave the inlet system to GC/MS
6.2.5 External standard calculation and data presentation.
through“JetPulseInjection”(Fig.2).Whiletheinletsystemis
in “Sample Loop Pressurization”, the sample loop (6.4.4)is
6.3 Gas chromatography (GC)—Chromatographic system
pressurized directly with hydrogen samples or calibration
capableofobtainingretentiontimerepeatabilityof0.05min(3
standards without pressure regulation or flow restriction.
s) throughout the analysis.
Afterwards, a six-port sample valve (6.4.1) switches the inlet
6.3.1 Interface with MS—Aheated interface connecting the
system to “Jet Pulse Injection”, in which pressurized hydrogen
GC column to the MS ion source.
in the sample loop is released instantaneously onto the GC
6.3.2 GC Column—A 0.25mm ID 30m 0.25 µm film thick-
column (6.3.2) and jet pulse split (6.4.5). Since the sample
ness DB-5 column has been successfully used to perform this
pressureishigh,allpartsoftheinletsystemmustbecapableof
analysis. Other capillary columns may be used provided
working at pressures of 1500 psi or higher.
chromatographicpeaksdonotsignificantlytail.Oneendofthe
GC column is connected to the Jet Pulse Split (6.4.5) and the 6.4.1 Six Ports Valve—This valve is used to switch from
other end is connected to the ion source inlet of a mass “Sample Loop Pressurization” (Fig. 1) to “Jet Pulse Injection”
spectrometer. (Fig. 2).
D7649 − 10
FIG. 3 m/e18 Extracted Ion Chromatogram of Sample Analysis with Co-Injection of Ambient Air
6.4.2 Samples and Calibration Standards—All calibration 6.4.5.3 Inlet of an electronic flow controller (EFC) with its
standards and samples are prepared or collected in 1800 psi outlet to ambient air. The flow rate of this EFC is always
pressure rated containers with a DOT 3A1800 label (United electronicallysetat150mL/mintoventmostoftheGCinjector
StatedDepartmentofTransportationmandatedlabel)affixedto split flow (72mL/min) during “Sample Loop Pressurization”
the outside surface. All calibration standards and samples are (Fig.1)andreleasedhydrogenfrompressurizedsampleloopin
connected to the inlet system before beginning an analytic “Jet Pulse Injection” (Fig. 2).
sequencetominimizethepotentialforairormoisturecontami- 6.4.6 Digital Vacuum Gauge—capable of measuring abso-
nation due to addition or replacement of standard or sample lute pressure at vacuum range 0 to 12,000 milli-torr (mtorr or
-3
containers. 10 torr). For the vacuum range from 0 to 1000 mtorr, the
6.4.3 Vacuum Pump—an oil vacuum pump that can pump accuracy is 6 10% or6 10 mtorr, whichever is larger.
down to 50 mtorr or less. 6.4.7 Digital Pressure Gauges—Two types of digital pres-
6.4.4 Sample Loop—stainless steel tubing with ⁄16 in. OD sure gauges are required. A pressure gauge 0 to 1000 psig is
and 2 mL inside volume. Both ends of the sample loop are used to measure sample and standard final pressure. Another
connected to a six port valve (6.4.1). digital pressure gauge in the low and narrow pressure range,
6.4.5 Jet Pulse Split—a T-union connects the following such as 0 to 2000 torr, is used to measure the pressure of pure
three portions. gases in initial standard preparation.
6.4.5.1 Six port valve (6.4.1) 6.4.8 Pressure Regulator—A 10,000 psi pressure regulator
6.4.5.2 Inlet of GC column (6.4.2) is used to reduce UHP hydrogen pressure to approximate 400
D7649 − 10
psi for calibration standard preparation. It is also used to 8. Preparation of Apparatus
pressurize the inlet system during method blank analysis, and
8.1 GC/MS—Placeinserviceinaccordancetothemanufac-
during inlet system flushing.
turer’s instructions. Perform daily mass calibration using
FC-43.As stated in 6.1, each of the peak intensities of m/e 18,
7. Reference Standards
28, 29, and 32 should be less than 10% of m/e 69 in the mass
7.1 Typical reference standards are listed in Fig. 1.Two
spectrum of FC-43 used for mass calibration. In order to
standardspreparedinheliumcontaining100ppmvO and100
achieve this condition, the GC column flow rate of GC/MS
ppmv N , are commercial available. Remaining standards
system should be set at a high flow rate, such as, 2mL/min,
listed in Fig. 1 are prepared as per below.
while the system is in standby mode to remove any air in the
7.2 0.5% CO,Ar,N and O in hydrogen—An evacuated
2 2 2 carrier gas line. In addition, when any air may be introduced
1-L cylinder is connected to four pressure-regulated com-
into the carrier gas system, such as when changing the
pressed gas cylinders containing reagent or UHP grade CO ,
2 hydrogen carrier gas tank, the GC total split flow rate is set at
Ar, N and O . The system is evacuated to less than 500 mtorr
2 2 100mL/min for an hour to rapidly remove air in the carrier gas
with all the regulators opened and the main cylinder valves
line.
closed. With the system isolated from vacuum pump, the 1-L
cylinder valve is opened and 100 torr of each target compound
9. Procedure
fromthecompressedgascylindersisexpandedintothesystem
9.1 The detailed procedures used to perform jet puls
...