1、Designation: D5599 15Standard Test Method forDetermination of Oxygenates in Gasoline by GasChromatography and Oxygen Selective Flame IonizationDetection1This standard is issued under the fixed designation D5599; the number immediately following the designation indicates the year oforiginal adoption
2、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. Scope*1.1 This test method covers a gas chromatographic proce-dure for the quantitativ
3、e determination of organic oxygenatedcompounds in gasoline having a final boiling point not greaterthan 220 C and oxygenates having a boiling point limit of130 C. It is applicable when oxygenates are present in the0.1 % to 20 % by mass range.1.2 This test method is intended to determine the massconc
4、entration of each oxygenate compound present in a gaso-line. This requires knowledge of the identity of each oxygenatebeing determined (for calibration purposes). However, theoxygen-selective detector used in this test method exhibits aresponse that is proportional to the mass of oxygen.Itis,therefo
5、re, possible to determine the mass concentration ofoxygen contributed by any oxygenate compound in the sample,whether or not it is identified. Total oxygen content in agasoline may be determined from the summation of theaccurately determined individual oxygenated compounds. Thesummed area of other,
6、uncalibrated or unknown oxygenatedcompounds present, may be converted to a mass concentrationof oxygen and summed with the oxygen concentration of theknown oxygenated compounds.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard
7、.1.4 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 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced
8、Documents2.1 ASTM Standards:2D1744 Test Method for Determination of Water in LiquidPetroleum Products by Karl Fischer ReagentD4175 Terminology Relating to Petroleum, PetroleumProducts, and LubricantsD4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsE594 Practice for Testi
9、ng Flame Ionization Detectors Usedin Gas or Supercritical Fluid ChromatographyE1064 Test Method for Water in Organic Liquids by Coulo-metric Karl Fischer TitrationE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs3. Terminology3.1 Definitions:3.1.1 indepen
10、dent reference standardscalibration samplesof the oxygenates which are purchased or prepared frommaterials independent of the quality control check standardsand used for intralaboratory accuracy.3.1.2 oxygenate, nan oxygen-containing compound, suchas an alcohol or ether, which may be used as a fuel
11、or fuelsupplement.3.1.3 quality control check standardscalibration samplesof the oxygenates for intralaboratory repeatability.4. Summary of Test Method4.1 An internal standard of a noninterfering oxygenate, forexample, 1,2-dimethoxyethane (ethylene glycol dimethylether) is added in quantitative prop
12、ortion to the gasolinesample. A representative aliquot of the sample and internal1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0L on Gas Chromatography Methods.Current editio
13、n approved June 1, 2015. Published July 2015. Originally approvedin 1994. Last previous edition approved in 2010 as D5599 00 (2010). DOI:10.1520/D5599-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMS
14、tandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1standard is injected into a
15、gas chromatograph equipped with acapillary column operated to ensure separation of the oxygen-ates. Hydrocarbons and oxygenates are eluted from thecolumn, but only oxygenates are detected with the oxygen-selective flame ionization detector (OFID).Adiscussion of thisdetector is presented in Section 6
16、.4.2 Calibration mixtures are used for determining the reten-tion times and relative mass response factors of the oxygenatesof interest. Suggested calibrant materials are listed in 8.2.4.3 The peak area of each oxygenate in the gasoline ismeasured relative to the peak area of the internal standard.
17、Aquadratic least-squares fit of the calibrated data of eachoxygenate is applied and the concentration of each oxygenatecalculated.NOTE 1While 1,2-dimethoxyethane has been found to be an appro-priate internal standard, other oxygenates may be used provided they arenot present in the sample and do not
18、 interfere with any compound ofinterest.5. Significance and Use5.1 In gasoline blending, the determination of organicoxygenated compounds is important. Alcohols, ethers, andother oxygenates are added to gasoline to increase the octanenumber and to reduce tailpipe emissions of carbon monoxide.They mu
19、st be added in the proper concentration and ratios tomeet regulatory limitations and to avoid phase separation andproblems with engine performance or efficiency.5.2 This test method provides sufficient oxygen-to-hydro-carbon selectivity and sensitivity to allow determination ofoxygenates in gasoline
20、 samples without interference from thebulk hydrocarbon matrix.6. Theory of OFID Operation6.1 The detection system selective for organic oxygenconsists of a cracking reactor, hydrogenating reactor(methanizer), and a flame ionization detector (FID). Thecracking reactor, connected immediately after the
21、 gas chro-matographic capillary column, consists of a Pt/Rh capillarytube. Carbon monoxide (CO) is formed from compoundscontaining oxygen according to the following reaction:CxHyOzzCO1y/2!H21x 2 z!C (1)6.2 An excess layer of carbon is created in the Pt/Rh tube ofthe cracking reactor from the introdu
22、ction of hydrocarbonsfrom the sample or, if so designed, from a hydrocarbon (forexample, pentane or hexane) doping system, or both. This layerof carbon facilitates the cracking reaction and suppresseshydrocarbon response.6.3 The carbon monoxide formed in the cracking reactor isconverted to methane i
23、n the hydrogenating reactor according tothe following reaction:CO13H2CH41H2O (2)The CH4is subsequently detected with an FID.6.4 The methanizer consists either of a short porous layeropen tubular (PLOT) glass capillary tube internally coated withaluminum oxide with adsorbed nickel catalyst or stainle
24、ss steeltubing containing a nickel-based catalyst. It is installed withinor before the FID and is operated in the range from 350 C to450 C, depending on the instruments manufacturer.NOTE 2Gasolines with high sulfur content may cause a loss indetector sensitivity thereby limiting the number of sample
25、s that can beanalyzed before the catalyst needs replacement.7. Apparatus7.1 Gas ChromatographAny gas chromatograph can beused having the following performance characteristics:7.1.1 Column Temperature ProgrammerThe chromato-graph must be capable of reproducible linear temperatureprogramming over a ra
26、nge sufficient for separation of thecomponents of interest.7.1.2 Sample Introduction SystemAny system capable ofintroducing a representative 0.1 L to 1.0 L liquid sample intothe split inlet device of the gas chromatograph. Microlitresyringes, autosamplers, and liquid sampling valves have beenused su
27、ccessfully. The split injector should be capable ofaccurate split control in the range from 10:1 to 500:1.7.1.3 Carrier and Detector Gas ControlConstant flowcontrol of carrier and detector gases is critical to optimum andconsistent analytical performance. Control is best provided bythe use of pressu
28、re regulators and fixed flow restrictors. Thegas flow rates are measured by any appropriate means. Thesupply pressure of the gas delivered to the gas chromatographmust be at least 70 kPa (10 psig) greater than the regulated gasat the instrument to compensate for the system back pressure.In general,
29、a supply pressure of 550 kPa (80 psig) will besatisfactory.7.2 OFID Detector System, consisting of a cracking reactor,methanizer, and FID. A schematic of a typical OFID system isshown in Fig. 1.7.2.1 The detector must meet or exceed the typical specifi-cations given in Table 1 of Practice E594 while
30、 operating in thenormal FID mode as specified by the manufacturer.7.2.2 In the OFID mode, the detector shall meet or exceedthe following specifications: (a) equal to or greater than 103linearity, (b) less than 100 ppm mass oxygen (1 ng O s)sensitivity, (c) greater than 106selectivity for oxygen com-
31、pounds over hydrocarbons, (d) no interference from coelutingcompounds when 0.1 L to 1.0 L sample is injected, (e)equimolar response for oxygen.7.3 ColumnA 60 m by 0.25 mm inside diameter fusedsilica open tubular column containing a 1.0 m film thicknessof bonded methyl silicone liquid phase is used.
32、Equivalentcolumns which provide separation of all oxygenates of interestmay be used.7.4 IntegratorUse of an electronic integrating device orcomputer is required. The device and software should have thefollowing capabilities:7.4.1 Graphic presentation of the chromatogram,7.4.2 Digital display of chro
33、matographic peak areas,7.4.3 Identification of peaks by retention time,7.4.4 Calculation and use of response factors, and7.4.5 Internal standard calculation and data presentation.D5599 1528. Reagents and Materials8.1 Purity of ReagentsReagents grade chemicals shall beused in all tests. Unless otherw
34、ise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high puri
35、ty to permit its use without lessening theaccuracy of the determination.8.2 Calibrant MaterialsThe following compounds may beused for calibrating the detector: methanol, ethanol,n-propanol, iso-propanol, n-butanol, tert-butanol, sec-butanol,iso-butanol, tert-pentanol, methyl tert-butylether (MTBE),t
36、ert-amylmethylether (TAME), ethyl tert-butylether (ETBE),di-iso-propylether (DIPE). (WarningThese materials arevery flammable and may be harmful or fatal when ingested,inhaled, or allowed to be absorbed through the skin.)8.3 Internal StandardUse one of the compounds listed in8.2 that is not present
37、in the sample. If all of the materials in 8.2are likely to be present in the test sample, use another organicoxygenate of high-grade purity that is separated from all otheroxygenates present (for example, 1,2-dimethoxyethane).8.4 DopantIf the OFID is so designed, reagent-gradepentane is used as a hy
38、drocarbon dopant for the crackingreactor. (WarningPentane is extremely flammable andharmful when inhaled.)8.5 Instrument GasesThe gases supplied to the gas chro-matograph and detector are:8.5.1 Air, zero grade. (WarningCompressed air is a gasunder high pressure and supports combustion.)8.5.2 Hydroge
39、n, pure grade, 99.9 % mol minimum purity.(WarningHydrogen is an extremely flammable gas underhigh pressure.)8.5.3 Helium or nitrogen as column carrier gas, 99.995 %mol minimum purity, or a blend of 95 % helium/5 % hydrogen,depending on the instruments manufacturer. (WarningHelium and nitrogen are co
40、mpressed gases under high pres-sure.)8.5.4 Additional purification of the carrier, air, and hydro-gen is recommended. Use molecular sieves, Drierite, charcoal,or other suitable agents to remove water, oxygen, and hydro-carbons from the gases.8.6 Sample ContainerGlass vials with crimp-on or screw-dow
41、n sealing caps with self-sealing polytetrafluoroethylene(PTFE)-faced rubber membranes are used to prepare calibra-tion standards and samples for analysis.9. Preparation of Apparatus9.1 Chromatograph and OFIDPlace instrument and de-tector into operation in accordance with the manufacturersinstruction
42、s. Install the capillary column according to PracticeE1510. Adjust the operating conditions to provide for separa-tion of all oxygenates of interest. Typical conditions used withthe column specified in 7.3 are listed in Table 1.9.2 System PerformanceAt the beginning of each day ofoperation, inject a
43、n oxygenate-free gasoline sample into thechromatograph to ensure minimum hydrocarbon response. Ifhydrocarbon response is detected, the OFID is not operatingeffectively and must be optimized according to the manufac-turers instructions before the sample can be analyzed.10. Calibration and Standardiza
44、tion10.1 Retention Time Identification Determine the reten-tion time of each oxygenate component by injecting smallamounts either separately or in known mixtures. Table 2 givestypical retention times for the oxygenates eluting from a 60 mmethyl silicone column temperature programmed according tocond
45、itions given in Table 1. A chromatogram of a blend ofoxygenates is given in Fig. 2.10.2 Preparation of Calibration SamplesThe calibrationsamples are prepared gravimetrically in accordance with Prac-tice D4307 by blending known weights of organic oxygenatecompounds (such as listed in 8.2) with a know
46、n weight internal3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United
47、States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Schematic of an OFIDD5599 153standard and diluting to a known weight with an oxygenate-free gasoline. The calibration samples should contain the sameoxygenates (in similar concentrations) as ar
48、e expected in thesample under test. Before preparing the standards, determinethe purity of the oxygenate stocks and make corrections for theimpurities found. Whenever possible, use stocks of at least99.9 % purity. Correct for the purity of the components forwater content determined by Test Method D1
49、744 or TestMethod E1064. Quality control check standards may beprepared from the same oxygenate stocks and by the sameanalyst. Quality control check standards must be prepared fromseparate batches of the final diluted standards.10.2.1 Tare a glass sample container and its PTFE-facedrubber septum sealing cap. Transfer a quantity of an oxygenateto the sample container and record the mass of the oxygenateto the nearest 0.1 mg. Repeat this process for any additionaloxygenates of interest except the internal standard. Addoxygenate-free gasoli
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