1、Designation: D7550 09Standard Test Method forDetermination of Ammonium, Alkali and Alkaline EarthMetals in Hydrogen and Other Cell Feed Gases by IonChromatography1This standard is issued under the fixed designation D7550; the number immediately following the designation indicates the year oforiginal
2、 adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a procedure for the determi-nation of ca
3、tions in hydrogen and other fuel cell feed gases. Ithas been successfully applied to other types of gaseous samplesincluding air, engine exhaust, and landfill samples. An ionchromatograph/conductivity detector (IC/CD) system is usedto determine cations. Sensitivity from low part per billion (ppb,g/l
4、, g/kg) up to part per million (ppm, mg/l, mg/kg)concentration are achievable dependant on the amount ofhydrogen or other fuel cell gas sampled. This test method canbe applied to other gaseous samples requiring analysis of traceconstituents provided an assessment of potential interferenceshas been a
5、ccomplished.1.2 The values stated in inch-pound units are to be regardedas standard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standa
6、rd to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent Water3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 densitymass per unit
7、 of volume of the fuel gas or airbeing considered.3.1.2 gaseous fuelmaterial to be tested, as sampled, with-out change of composition by drying or otherwise.3.1.3 relative humidityratio of actual pressure of existingwater vapor to maximum possible pressure of water vapor inthe atmosphere at the same
8、 temperature, expressed as apercentage.3.1.4 relative densityratio of the density of the gaseousfuel, under the observed conditions of temperature andpressure, to the density of dried air, of normal carbon dioxidecontent (0.03%), at the same temperature and pressure.3.1.5 ion chromatographyliquid ch
9、romatographic tech-nique for the rapid separation of ionic species in solution usingion exchange columns and determined using a variety offlow-through detection system most commonly suppressedconductivity.3.1.6 ion chromatograph (IC)Instrument for performingion chromatography.3.1.7 ion conductivity
10、detector (ICD) instrument compo-nent that measures the total change in conductivity of theeluent and analytes flowing between two electrodes.3.1.8 chemical suppressiontechnique using a chemicalreaction to reduce the eluent conductivity and to enhanceanalyte response in ion chromatographic systems us
11、ing aconductivity detector.3.1.9 electronic suppressiontechnique using an electro-chemical reaction to enhance analyte response in ion chromato-graphic systems using a conductivity detector.3.1.10 eluentsolvent used to transport analytes through anion chromatographic column, suppressor and detector.
12、3.1.11 dscmdry standard cubic meter.4. Summary of Test Method4.1 Hydrogen or other fuel cell gas is passed through ahydrogen quality sampling apparatus containing a calibratedflow meter and a filter module loaded with a nylon filters (1.0m pore size). Alternative sampling apparatus can be usedprovid
13、ed the fuel cell gas can be accurately measured andcollected free of contamination. When necessary a pump isused to draw sample through the filter module. Filters areremoved from the filter module weighed and extracted intovolumetrically calibrated vessels. The recovered solutions are1This test meth
14、od is under the jurisdiction ofASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.14 on Hydrogen andFuel Cells.Current edition approved Sept. 1, 2009. Published October 2009. DOI: 10.1520/D7550-09.2For referenced ASTM standards, visit the ASTM website, www.astm.o
15、rg, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesNOTICE: This s
16、tandard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International (www.astm.org) for the latest information1analyzed for cations using an ion chromatograph/conductivitydetector (IC/CD) system. The cations present elute as peaksfrom the column. The area under th
17、e peaks is proportional tothe amount in the sample. The sample amount is measured andcompared to the amount found for standards used to generatea calibration curve. These functions/calculations are mostcommonly performed by chromatography software.5. Significance and Use5.1 Low operating temperature
18、 fuel cells such as protonexchange membrane (PEM) fuel cells require high purityhydrogen for maximum material performance and lifetime.Analysis to part-per-billion (ppb) concentration of individualcation contaminants such as potassium, sodium and ammo-nium in hydrogen and related fuel cell supply ga
19、ses isnecessary for assuring a feed gas of sufficient purity to satisfyfuel cell system needs. More specifically, cations such asammonium causes irreversible performance degradation ofproton exchange membranes used in low temperature fuel cellsby reacting with protons in the membrane to form ammoniu
20、mions.5.2 Although not intended for application to gases otherthan hydrogen and related fuel cell supply gases, techniqueswithin this test method can be applied to other gaseous samplesrequiring cation analysis.6. Equipment and Instrumentation6.1 Sampling ApparatusDevelopment of a suitable hydro-gen
21、 and other fuel cell feed gas sampling apparatus andappropriate sampling practices is on-going. Any appropriateapparatus can be used provided it can safely provide acontamination free filtered sample of a volumetrically mea-sured fuel cell feed gas.6.2 Nylon filters - 1.0 m pore size.6.3 Metering Sy
22、stemTypically, the metering system in-cludes a thermometer(s) capable of measuring temperature towithin 3 C (5.4 F), a dry gas meter capable of measuringvolume to within 2 percent, and related equipment. An alter-native to the thermometers and dry gas meters is an equivalenttemperature compensated d
23、ry gas meter. When needed, aleak-free pump is interfaced between the filter module and thedry gas meter.6.4 Sampling LineThe sampling line and any other sam-pling apparatus shall be made of material which is inert to thegas sampled and cations including ammonia.6.5 IC Analysis:6.5.1 Ion chromatograp
24、h (IC) standard manufacture fittedwith a conductivity detector, autosampler, and interfaced to acomputer or other data storage/collection device. The follow-ing conditions have been successfully used:6.5.1.1 Cation Exchange Separator Column: IonPac CS12A(4250mm).6.5.1.2 Cation Exchange Guard Column:
25、 IonPac CG12A(450mm).6.5.1.3 Eluent: 20mM MSA, Flow rate: 1.0 ml/min.6.5.1.4 Detection: Suppressed conductivity, recycle mode6.5.1.5 Suppressor: CSRS 300 (4mm).6.5.2 Type 1 Water (Specification D1193-06).6.5.3 Graduated Cylinder, various sizes as needed.6.5.4 Beakers, 150 ml.6.5.5 Volumetric Pipette
26、s, Class A borosilicate glass, vari-ous sizes as needed.6.5.6 Volumetric Flasks, Class A, various sizes as needed.6.5.7 Balance, analytical, accurate to 0.1 g.6.5.8 Magnetic stirrer, thermally insulated, and Tefloncoated stirring bar.6.5.9 Micropipette, 0.1 ml to 1 ml.7. Apparatus7.1 Sampling is acc
27、omplished using a hydrogen qualitysampling adaptor (HQSA) or other appropriate sampling ap-paratus fitted with a filter module containing a nylon filter (1.0m pore size). The HQSA is appropriate for sampling of highpressure gas lines and is defined as apparatus used to interfacewith a hydrogen deliv
28、ery receptacle such as a vehicle fuelingnozzle and deliver sample to a collection vessel. Free flow ofsample gas through the filter can be made by using a lowpressure sample line or by drawing sample through the sampletrain using a pump. WarningCaution, hydrogen and relatedflammable gas sampling sho
29、uld be accomplished in a wellventilated locale where hydrogen gas will not build up toexplosive levels. WarningCaution, hydrogen at high pres-sures is an explosion hazard and may spontaneously ignitecreating an invisible flame when leaked through a seam orpinhole.7.2 Determining the Target Minimum C
30、ation Concentration(TMCC)The user should identify the target minimum cationconcentration needed for the application. When the determina-tion of multiple cations is desired, the cation chosen should bethe one likely to be present in the lowest concentration.7.2.1 Determining the TMCC:7.2.1.1 Assumpti
31、ons: :(1) All the cations in the sample are recovered from thefilter(2) Evaporative loses of substances such as ammonium areinsignificant.7.2.1.2 Calculations:MDCC 5 C1/VR(1)Where:MDCC = Minimum Detectable Cation ConcentrationC1 = lowest concentration on a calibration curve.VR = assumed liquid volum
32、e for the recovery solution,ml7.2.2 Planned Sampling Volume (PSV) The plannedsample volume is the volume of gas that must be sampled tocollect for analysis a quantifiable mass of a particular cation.The PSV is based on the TMCC and the target contaminantconcentration, and is further adjusted by a sa
33、fety margin toassure quantification.7.2.2.1 Calculations:PSV 5 TMCC/STC 3F (2)Where:PSV = planned sample volume, dscmD7550 092TMCC = analytical target minimum cation concentration,mgSTC = target contaminant concentration, mg/dscmF = safety margin, F 17.2.3 Planned Sampling Time (PST)The planned sam-
34、pling time is the time required to collect the minimum samplevolume at the proposed volumetric sampling rate (VSR). Theuser should use an average volumetric sampling rate appropri-ate for the fuel source tested. If the VSR cannot be achieved inthe field, the sampling time should be revised using the
35、following equation to achieve the target PSV.PST 5 PSV/VSR (3)PST = planned sampling time, unit timePSV = planned sample volume, dscmVSR = achievable volumetric sampling rate, dscm/unit time7.3 Sampling OperationSample the required amount ofgas as per the determination under 7.2. Upon completion ofs
36、ampling, isolate the filter sampling module and remove itfrom the hydrogen sampling apparatus. Transfer filter samplingmodule to the sample recovery area. This area should be cleanand rigorously free of cation contamination. Sample recoveryshould be performed in a laboratory.8. Reagents and Material
37、s8.1 Ionic strength adjustor (ISA), pH adjusting solution.8.2 Standard solutions - certified reference material quality.The following analytes as needed8.2.1 Ammonia - 0.1M NH4Cl or 1400 ppm as N.8.2.2 Nitrate - Stock 1000 mg/L as N Nitrate standard,which is equivalent to 4428.6 mg/L Nitrate as Nitr
38、ate. (Op-tional anion analysis)8.2.3 Sulfate - 1000 mg/l sulfate standard. (Optional anionanalysis)8.2.4 Sodium - 100 mg/l sodium standard8.2.5 Potassium - 100 mg/l potassium standard.8.2.6 Magnesium - 100 mg/l magnesium standard.8.2.7 Calcium -100 mg/l calcium standard.8.3 Calibration verification
39、check standardAs part of anoverall QA/QC program calibration verification check stan-dards should be analyzed with each set of samples in applica-tion of this standard test method. For example an ammoniumcalibration check standard at 28 mg NH3-N/L is prepared asfollows.8.3.1 Pipette 10 ml of 0.1M NH
40、4Cl standard solution into a500 ml volumetric flask and dilute to the mark with 0.04 NH2SO4. The Calibration verification check standard value is0.002 M NH4Cl, or 28 mg NH3-N/L. Calibration Verificationmust be prepared prior to use.8.4 Methanesulfonic acid (MSA): 1.0 MUsed in prepara-tion of eluent
41、for IC analysis8.5 WaterDeionized or distilled to conform to Specifica-tions D1193-99e1, Type 3. Water should be blank-checked forammonium ion prior to use.8.6 Sulfuric Acid Solution0.1N 8.88.7 IC Sparge gas (optional)Helium of high purity99.995%, low nitrogen content.9. Standards9.1 Working standar
42、ds are prepared each week and arestored in a refrigerator at 10 C. Calibration is performed usingthe identical instrument parameters as are used in the analysissamples.9.2 Prepare initial calibration standards using 1000 mg/lstock standards. Prepare at least four standards spanning thedesired calibr
43、ation range. For each calibration point, transferthe stock solution using a pipette directly into the appropriatesized volumetric flask, add 0.1 N H2SO4 and bring to volumeusing deionized water.NOTE 1Ammonium calibration standards will evolve ammonia overtime at room temperature; therefore, they sho
44、uld be prepared as close aspossible to use.9.3 For analysis of cations present in the recovered samplesolutions at 1 ppm or above a typical calibration curve can beprepared using the 1000 ppm stock standard by first preparinga 100 ppm standard. This standard is prepared by volumetri-cally adding 5 m
45、l of stock standard to a 500 ml volumetric flaskthen adding deionized water to volume. Once the 10 ppmstandard is prepared, a typical calibration set of points can beprepared as indicated in Table 1. Refrigerate the standards asnecessary until ready to perform the analysis.10. Analysis10.1 As necess
46、ary, take the recovered samples out of therefrigerator and let them sit until they reach room temperature.10.2 Prepare a matrix spike by transfering the sample to aclean beaker, and adding an appropriate amount of the 10 ppmcation standard prepared under section 10 to make a 1 ppmcation spiked sampl
47、e.10.3 Charge the IC eluent reservoir with freshly preparedeluent. Turn on all supply gases and pump the eluent throughthe system for at lease 30 min before starting calibration. Makesure baseline and background conductivity are low.TABLE 1 Calibration Curve Data PointsCalibrationLevelTargetConcentr
48、ation(ppm)Amount of 10 ppmStandard (ml)FinalVolume1 2.0 20 1002 1.5 15 1003 1.0 10 1004 0.5 5 1005 0.1 1 100D7550 09310.4 Fill autosampler vials with about 5ml of standard,control, or sample. Place the vials into the autosampler tray. Atypical run list is shown below but these elements should berand
49、omized in an effort to eliminate sampling errors:Vial number Sample I.D.1 Deionized water2 - 5 Standards five different levels from lowto high6 Control7 Reagent Blank8 Sample #19 Sample #1 Duplicate (as necessary)10 Sample #1 Matrix Spike11 Sample #1 Matrix Spike Duplicate (asnecessary)12 Control13 - 17 Standards five different levels from lowto high18 Eluent Blank19 Deionized water11. Calculations11.1 Calibration Standards:11.1.1 Response Factors (RF):RF 5 Analyte Response Curve Area/Analyte Concentration ug/ml!(4)11.1.2 Average
