1、Designation: D6228 10Standard Test Method forDetermination of Sulfur Compounds in Natural Gas andGaseous Fuels by Gas Chromatography and FlamePhotometric Detection1This standard is issued under the fixed designation D6228; the number immediately following the designation indicates the year oforigina
2、l 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 covers the determination of individualvolatile su
3、lfur-containing compounds in gaseous fuels by gaschromatography (GC) with a flame photometric detector (FPD)or a pulsed flame photometric detector (PFPD). The detectionrange for sulfur compounds is from 20 to 20 000 picograms(pg) of sulfur. This is equivalent to 0.02 to 20 mg/m3or 0.014to 14 ppmv of
4、 sulfur based upon the analysis of a 1-mLsample.1.2 This test method describes a GC method using capillarycolumn chromatography with either an FPD or PFPD.1.3 This test method does not intend to identify all indi-vidual sulfur species. Total sulfur content of samples can beestimated from the total o
5、f the individual compounds deter-mined. Unknown compounds are calculated as monosulfur-containing compounds.1.4 The values stated in SI units are to be regarded asstandard. The values stated in inch-pound units are for infor-mation only.1.5 This standard does not purport to address all the safetycon
6、cerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1265 Practice for Sampling Liquefied Petr
7、oleum (LP)Gases, Manual MethodD1945 Test Method for Analysis of Natural Gas by GasChromatographyD3609 Practice for Calibration Techniques Using Perme-ation TubesD4468 Test Method for Total Sulfur in Gaseous Fuels byHydrogenolysis and Rateometric ColorimetryD4626 Practice for Calculation of Gas Chrom
8、atographicResponse FactorsD5287 Practice for Automatic Sampling of Gaseous FuelsD5504 Test Method for Determination of Sulfur Com-pounds in Natural Gas and Gaseous Fuels by Gas Chro-matography and ChemiluminescenceE840 Practice for Using Flame Photometric Detectors inGas Chromatography2.2 EPA Standa
9、rds:EPA15 Determination of Hydrogen Sulfide, Carbonyl Sul-fide and Carbon Disulfide Emissions from StationarySources, 40 CFR, Chapter 1, Part 60, Appendix AEPA16 Semicontinuous Determination of Sulfur Emis-sions from Stationary Sources, 40 CFR, Chapter 1, Part60, Appendix A3. Terminology3.1 Abbrevia
10、tions:3.1.1 A common abbreviation of a hydrocarbon compoundis to designate the number of carbon atoms in the compound.A prefix is used to indicate the carbon chain form, while asubscript suffix denotes the number of carbon atoms, forexample, normal decane = n-C10, isotetradecane = i-C14.3.1.2 Sulfur
11、 compounds commonly are referred to by theirinitials, chemical or formula, for example, methyl mercaptan =MeSH, dimethyl sulfide = DMS, carbonyl sulfide = COS,di-t-butyl trisulfide = DtB-TS, and tetrahydothiophene = THTor thiophane.4. Summary of Test Method4.1 Sample CollectionSulfur analysis ideall
12、y is performedon-site to eliminate potential sample deterioration duringstorage. The reactive nature of sulfur components may poseproblems both in sampling and analysis. Samples should becollected and stored in containers that are nonreactive to sulfurcompounds, such as Tedlar3bags. Sample container
13、s should befilled and purged at least three times to ensure representative1This test method is under the jurisdiction ofASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.05 on Determination ofSpecial Constituents of Gaseous Fuels.Current edition approved Dec. 1,
14、 2010. Published January 2011. Originallyapproved in 1998. Last previous edition approved in 2003 as D6228 98(2003).DOI: 10.1520/D6228-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
15、information, refer to the standards Document Summary page onthe ASTM website.3Registered trademark. Available from DuPont de Nemours, E. I., however, there are variations indesign. The pulsed flame photometric detector (PFPD) is oneof the new FPD designs. The pressure and flow rate of thehydrogen an
16、d air gases used in the detector may be different.D6228 102The selection of which detector to use should be based on itsperformance for the intended application. The detector shouldbe set according to the manufacturers specifications and tunedto the best performance of sensitivity and selectivity as
17、 needed.6.1.5.1 Principle of OperationWhen sulfur-containingcompounds are burned in a hydrogen-rich flame, they quanti-tatively produce a S2* species in an excited state (Eq 1 and Eq2). The light emitted from this species is detected by aphotomultiplier tube (PMT) (Eq 3).6.1.5.2 Flame Photometric De
18、tector (FPD)in the FPD a393-nm bandpass optical filter is normally used to enhance theselectivity of detection. The FPD selectivity normally is about106to 1 by mass of sulfur to mass of carbon.6.1.5.3 Pulsed Flame Photometric Detector (PFPD)Inthe PFPD the propagation of the flame produces gas phaser
19、eactions which result in light emissions with specific lumines-cent spectra and lifetimes. The differences in specific emissionlifetimes combined with a broad-band optical filter and thekinetics of the propagating flame, allow both time and wave-length information to be used to improve the PFPDs sel
20、ectiv-ity and sensitivity. The PFPD selectivity relative to hydrocar-bon is 106or better, depending on gate settings and otherfactors. Using gated electronics permit the acquisition of two,simultaneous, mutually selective chromatograms (for example,sulfur and hydrocarbon).RS 1 O2n CO21 SO2(1)2SO21 4
21、H24H2O 1 S2* (2)S2*S21 hn (3)where:hn = emitted light energy.6.1.5.4 Detector ResponseThe intensity of light is notlinear with the sulfur concentration but is proportional approxi-mately to the square of the sulfur concentration. The relation-ship between the detector response (RD) and the sulfur co
22、n-centration (S) is given by Eq 4 and Eq 5. The n-factor usuallyis less than 2.0.RDa S#n(4)Log S# a 1/n Log R (5)where:n = exponential factor (1.7 to 2.0).6.1.5.5 LinearityThe linear calibration curve can be madeusing a log-log plot. Some instruments provide optionalelectronic algorithims to produce
23、 a signal with direct linearresponse. The dynamic range of this linear relationship is about1 3 103.6.2 ColumnThe capillary column shall be chosen to becompatible with the detector and detector gas flow raterequirements.6.2.1 FPD ColumnA 60-m by 0.53-m ID fused silicaopen tubular column containing a
24、 5-m film thickness ofbonded methyl silicone liquid phase is used.6.2.2 PFPD ColumnA fused silica capillary column with0.32-mm ID or smaller and sufficient length (for example,30-m or 60-m) and phase to separate the sulfur species is used.Helium carrier gas flow rate of 2.0 mL/minute or slower isuse
25、d.6.2.3 The column shall provide adequate retention andresolution characteristics under the experimental conditionsdescribed in 7.3. One example of a capillary column andoperating conditions used with the FPD is shown in Table 1.Two examples of columns and operating conditions used withthe PFPD are
26、shown in Table 2. Other columns, which canprovide equivalent separation, can be used as well.6.3 Data Acquisition:6.3.1 RecorderA 0- to 1-mV range recording potentiom-eter, or equivalent, with a full-scale response time of2sorlesscan be used.6.3.2 IntegratorThe use of an electronic integrating de-vi
27、ce or computer is recommended. The device and softwaremust have the following capabilities:6.3.2.1 Graphic presentation of the chromatogram.6.3.2.2 Digital display of chromatographic peak areas.6.3.2.3 Identification of peaks by retention time or relativeretention time, or both.7. Reagents and Mater
28、ials7.1 Sulfur Permeation Tube StandardsGaseous standardsgenerated from individual or a combination of certified perme-ation tubes at a constant temperature and flow rate shall be usedfor all calibrations. Each permeation tube will be weighed tothe nearest 0.1 mg on a periodic basis after the permea
29、tion ratehas equilibrated and remains constant. The standard concen-tration is calculated by mass loss and dilution gas flow rate.Impurities permeated from each tube must be detected, mea-sured, and accounted for in the mass loss, if they are presentabove a level of 0.1 % of the permeated sulfur spe
30、cies. SeePractice D3609.7.2 Compressed Cylinder Gas StandardsAs an alterna-tive, blended gaseous sulfur standards may be used if a meansto ensure accuracy and stability of the mixture is available.These mixtures can be a source of error if their stability duringstorage cannot be guaranteed. (Warning
31、Sulfur compoundsmay be flammable and harmful or fatal if ingested or inhaled.)7.3 Carrier GasHelium, hydrogen, or nitrogen of highpurity (99.999 % min purity). (WarningHelium, hydrogen,and nitrogen are compressed gases under high pressure.)Additional purification is recommended by the use of molecu-
32、lar sieves or other suitable agents to remove water, oxygen, andhydrocarbons. Available pressure must be sufficient to ensure aconstant carrier gas flow rate (see 6.1.4).7.3.1 The FPD and PFPD have different requirements forthe carrier gas flow rate. For example, with a PFPD the carrierTABLE 1 GC-FP
33、D Operating ParametersGas Sample Loop: 1.0 mL at 120CInjection Type: On-columnColumn: 60-m 3 0.53mm ID 3 5 film, fused silica opentublar column with bonded methyl silicone liquidphaseCarrier Gas: He at 11.0 mL/min or at a flow rate allowing CH4elutes at approximately 2.1 minColumn Oven: 30C hold 1.5
34、 min, 15C/min to 200C, hold 8 min, oras neededDetector: Flame Photometric Detector (FPD) H2/air ratiospecified by manufacturer, 250C, 20mL/min, helium makeup gasD6228 103gas flow rate should not exceed 2.0 mL/minute (He) to preventcooling the flame. Consult the detector manufacturer forguidance.7.3.
35、2 When using hydrogen as the carrier gas, adjustmentsto the detector hydrogen flow rate may be necessary; consultthe detector manufacturer for guidance.7.3.3 Nitrogen should not be used as the carrier gas with thePFPD.7.4 HydrogenHydrogen of high purity (99.999 % minpurity) is used as fuel for both
36、detectors. (WarningHydrogen is an extremely flammable gas under high pressure.)7.5 AirHigh-purity (99.999 % min purity) compressed airis used as the oxidant for both detectors. (WarningCompressed air is a gas under high pressure that supportscombustion.).8. Preparation of Apparatus and Calibration8.
37、1 ChromatographPlace in service in accordance withthe manufacturers instructions. Typical operating conditionsare shown in Table 1 (FPD) and Table 2 (PFPD).8.2 DetectorPlace the detector in service in accordancewith the manufacturers instructions. Hydrogen and air flowsare critical and must be adjus
38、ted properly in accordance withthe instruction furnished by the manufacturer.8.2.1 Flame Photometric Detector (FPD)With the FPDflame ignited, monitor the signal to verify compliance with thesignal noise and drift specified by the manufacturer. The FPDflame should be maintained to give consistent and
39、 optimumsensitivity for the detection range.8.2.2 Pulsed Flame Phototmetric Detector (PFPD)Ensure that the sulfur emission, pulse frequency, electronicgating, and calculated dectectivity meet the manufacturersspecifications.8.3 Sample InjectionA sample loop of 1.0 mL may beused for performance check
40、. A linear calibration curve may bedetermined by using standards of varying concentrations or byinjecting a single calibration standard at different pressuresfrom 13.3 to 133 kPa (100 to 1000 torr). If the latter method isused, the concentration of sulfur component for calibration iscalculated using
41、 the following equation.Sn5Ps/Po!3Cn(6)where:Sn= calculated concentration of the sulfur compound inthe sampled gas on mole or volume basis,Ps= sampling pressure as absolute,Po= laboratory ambient pressure as absolute, andCn= concentration of the sulfur compound in the calibra-tion standard.8.4 Detec
42、tor Response CalibrationAnalyze the calibra-tion gas and obtain the chromatograms and peak areas.Determine the linear range of detector response using sampleinjection techniques illustrated in 8.3. A log/log plot or alinearized plot may be constructed with the linear correlationfactor calculated. Ca
43、lculate the relative sulfur response factor(see Practice D4626) of each sulfur compound at ambientpressure by:Fn5Sn/An!3Ln(7)where:Fn= sulfur response factor of compound,Sn= concentration of the sulfur compound in the sampledgas on mole or volume basis,An= peak area of the sulfur compound measured,
44、andLn= moles of sulfur in the compound.Example:Assume 1.0 ppmv of dimethyl sulfide (DMS) injected with a1.0-mL sample loop.1-ppmv DMS = 62.13/22.41 = 2.772 mg/m3(from Table3). 1.0 mL of 1-ppmv DMS = 2772-pg DMS = 2772 351.61 % = 1430-pg S. If the peak area of DMS response is15 850 counts, the respon
45、se factor Fn(S/peak) is 1430/15 8503 1 = 9.02 3 102(pg sulfur/unit area). The response factor(Fn) of 1.0-mL injection = 1.0/15 850 3 1=633 106(ppmvDMS/unit area).All sulfur compounds of the same class should have approxi-mately the same response factor. The response factor (Fn)ofTABLE 2 GC-PFPD Oper
46、ating ParametersParameter Column 1 Column 2Gas Sample Loop: 1.0 mL at 150C 1.0 mL at 150CInjection Type: Split; split ratio 50:1 Split: split ratio 50:1Column: Agilent GS-GasPro PLOT column, 30m3 0.32 mmIDAgilent J gas chromatography;pulsed flame photometric detector; sulfur compounds, odorantsTABLE
47、 4 Retention Times of Sulfur Components Shown in Fig. 1RT, min Compound RT, min Compound RT, min Compound2.09 methane 5.50 CS211.23 M-iPr-DS2.20 ethane 5.80 iPrSH 11.62 DEDS2.45 H2S 6.45 TBM 11.74 M-nPr-DS2.55 COS 6.70 nPrSH 11.90 M-tB-DS2.65 propane 6.80 MES 12.35 DMTS3.00 i-butane 7.80 thiophene 1
48、2.87 E-nPr-DS3.40 n-butane 8.25 DES 12.98 DiPr-DS3.52 MeSH 9.00 DMDS 13.50 iPr-tB-DS4.50 i-pentane 9.42 M-thiophenes 13.65 iPr-nPr-DS4.75 EtSH 9.95 THT 14.35 DtB-DS4.90 n-pentane 10.37 MEDS 14.55 DEt-TS5.10 DMS 11.00 C27thiophenes 17.15 DtB-TSTABLE 5 Flame Photometric Detector (FPD) Repeatability (S
49、ingleOperator and Apparatus)Sulfur Compound ppmv RepeatabilityCOS 2.07 60.06DMS 3.63 60.12NPM 3.72 60.12DMDS 2.00 60.06THT 6.44 60.16D6228 107ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the re
