ASTM D5599-2018 Standard Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection.pdf

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1、Designation: D5599 17D5599 18Standard 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 a

2、doption 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 procedure for the quan

3、titative determination of organic oxygenatedcompounds in gasoline having a final boiling point not greater than 220 C and oxygenates having a boiling point limit of 130 C.It is applicable when oxygenates are present in the 0.1 % to 20 % by mass range.1.2 This test method is intended to determine the

4、 mass concentration of each oxygenate compound present in a gasoline. Thisrequires knowledge of the identity of each oxygenate being determined (for calibration purposes). However, the oxygen-selectivedetector used in this test method exhibits a response that is proportional to the mass of oxygen. I

5、t is, therefore, possible to determinethe mass concentration of oxygen contributed by any oxygenate compound in the sample, whether or not it is identified. Totaloxygen content in a gasoline may be determined from the summation of the accurately determined individual oxygenatedcompounds. The summed

6、area of other, uncalibrated or unknown oxygenated compounds present, may be converted to a massconcentration of oxygen and summed with the oxygen concentration of the known oxygenated compounds.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are includ

7、ed in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regu

8、latory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organ

9、ization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products byHydrometer MethodD1744 Test Method for Determination of Water in Liquid Petroleum Products

10、 by Karl Fischer Reagent (Withdrawn 2016)3D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density MeterD4175 Terminology Relating to Petroleum Products, Liquid Fuels, and LubricantsD4307 Practice for Preparation of Liquid Blends for Use as Analytical StandardsE

11、594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid ChromatographyE1064 Test Method for Water in Organic Liquids by Coulometric Karl Fischer TitrationE1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs3. Terminology3.1 De

12、finitions:1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.04.0L on Gas Chromatography Methods.Current edition approved May 1, 2017June 1, 2018. Published June 2017September 2018.

13、 Originally approved in 1994. Last previous edition approved in 20152017 asD5599 15.D5599 175. DOI: 10.1520/D5599-17.10.1520/D5599-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume infor

14、mation, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been ma

15、de to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A

16、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 States13.1.1 independent reference standards, ncalibration samples of the oxygenates which are purchased or prepared frommaterials

17、independent of the quality control check standards and used for intralaboratory accuracy.3.1.2 oxygenate, nan oxygen-containing compound, such as an alcohol or ether, which may be used as a fuel or fuelsupplement.3.1.3 quality control check standards, ncalibration samples of the oxygenates for intra

18、laboratory repeatability.4. Summary of Test Method4.1 An internal standard of a noninterfering oxygenate, for example, 1,2-dimethoxyethane (ethylene glycol dimethyl ether) isadded in quantitative proportion to the gasoline sample.Arepresentative aliquot of the sample and internal standard is injecte

19、d intoa gas chromatograph equipped with a capillary column operated to ensure separation of the oxygenates. Hydrocarbons andoxygenates are eluted from the column, but only oxygenates are detected with the oxygen-selective flame ionization detector(OFID). A discussion of this detector is presented in

20、 Section 6.4.2 Calibration mixtures are used for determining the retention times and relative mass response factors of the oxygenates ofinterest. Suggested calibrant materials are listed in 8.2.4.3 The peak area of each oxygenate in the gasoline is measured relative to the peak area of the internal

21、standard. A quadraticleast-squares fit of the calibrated data of each oxygenate is applied and the concentration of each oxygenate calculated.NOTE 1While 1,2-dimethoxyethane has been found to be an appropriate internal standard, other oxygenates may be used provided they are not presentin the sample

22、 and do not interfere with any compound of interest.5. Significance and Use5.1 In gasoline blending, the determination of organic oxygenated compounds is important. Alcohols, ethers, and otheroxygenates are added to gasoline to increase the octane number and to reduce tailpipe emissions of carbon mo

23、noxide. They mustbe added in the proper concentration and ratios to meet regulatory limitations and to avoid phase separation and problems withengine performance or efficiency.5.2 This test method provides sufficient oxygen-to-hydro-carbon selectivity and sensitivity to allow determination of oxygen

24、atesin gasoline samples without interference from the bulk hydrocarbon matrix.6. Theory of OFID Operation6.1 The detection system selective for organic oxygen consists of a cracking reactor, hydrogenating reactor (methanizer), anda flame ionization detector (FID). The cracking reactor, connected imm

25、ediately after the gas chromatographic capillary column,consists of a Pt/Rh capillary tube. Carbon monoxide (CO) is formed from compounds containing oxygen according to thefollowing reaction:CxHyOzzCO1y/2!H 21x2z!C (1)6.2 An excess layer of carbon is created in the Pt/Rh tube of the cracking reactor

26、 from the introduction of hydrocarbons fromthe sample or, if so designed, from a hydrocarbon (for example, pentane or hexane) doping system, or both. This layer of carbonfacilitates the cracking reaction and suppresses hydrocarbon response.6.3 The carbon monoxide formed in the cracking reactor is co

27、nverted to methane in the hydrogenating reactor according to thefollowing reaction:CO13H 2CH41H2O (2)The CH4 is subsequently detected with an FID.6.4 The methanizer consists either of a short porous layer open tubular (PLOT) glass capillary tube internally coated withaluminum oxide with adsorbed nic

28、kel catalyst or stainless steel tubing containing a nickel-based catalyst. It is installed within orbefore the FID and is operated in the range from 350 C to 450 C, depending on the instruments manufacturer.NOTE 2Gasolines with high sulfur content may cause a loss in detector sensitivity thereby lim

29、iting the number of samples that can be analyzed beforethe catalyst needs replacement.7. Apparatus7.1 Gas ChromatographAny gas chromatograph can be used having the following performance characteristics:7.1.1 Column Temperature ProgrammerThe chromatograph must be capable of reproducible linear temper

30、ature programmingover a range sufficient for separation of the components of interest.7.1.2 Sample Introduction SystemAny system capable of introducing a representative 0.1 L to 1.0 L liquid sample into thesplit inlet device of the gas chromatograph. Microlitre syringes, autosamplers, and liquid sam

31、pling valves have been usedsuccessfully. The split injector should be capable of accurate split control in the range from 10:1 to 500:1.7.1.3 Carrier and Detector Gas ControlConstant flow control of carrier and detector gases is critical to optimum andconsistent analytical performance. Control is be

32、st provided by the use of pressure regulators and fixed flow restrictors.The gas flowD5599 182rates are measured by any appropriate means. The supply pressure of the gas delivered to the gas chromatograph must be at least70 kPa (10 psig) greater than the regulated gas at the instrument to compensate

33、 for the system back pressure. In general, a supplypressure of 550 kPa (80 psig) will be satisfactory.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 specificati

34、ons given in Table 1 of Practice E594 while operating in thenormal FID mode as specified by the manufacturer.7.2.2 In the OFID mode, the detector shall meet or exceed the following specifications: (a) equal to or greater than 103 linearity,(b) less than 100 ppm mass oxygen (1 ng Os) sensitivity, (c)

35、 greater than 106 selectivity for oxygen compounds overhydrocarbons, (d) no interference from coeluting compounds when 0.1 L to 1.0 L sample is injected, (e) equimolar response foroxygen.7.3 ColumnA 60 m by 0.25 mm inside diameter fused silica open tubular column containing a 1.0 m film thickness of

36、bonded methyl silicone liquid phase is used. Equivalent columns which provide separation of all oxygenates of interest may beused.7.4 IntegratorUse of an electronic integrating device or computer is required. The device and software should have thefollowing capabilities:7.4.1 Graphic presentation of

37、 the chromatogram,7.4.2 Digital display of chromatographic 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.8. Reagents and Materials8.1 Purity of ReagentsReagents grade chemicals sh

38、all be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.4 Other grades may be used, provided it is first ascertained that

39、 the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.8.2 Calibrant MaterialsThe following compounds may be used for calibrating the detector: methanol, ethanol, n-propanol,iso-propanol, n-butanol, tert-butanol, sec-butanol, iso-butanol, ter

40、t-pentanol, methyl tert-butylether (MTBE), tert-amylmethylether(TAME), ethyl tert-butylether (ETBE), di-iso-propylether (DIPE). (WarningThese materials are very flammable and may beharmful or fatal when ingested, inhaled, or allowed to be absorbed through the skin.)8.3 Internal StandardUse one of th

41、e compounds listed in 8.2 that is not present in the sample. If all of the materials in 8.2are likely to be present in the test sample, use another organic oxygenate of high-grade purity that is separated from all otheroxygenates present (for example, 1,2-dimethoxyethane).4 Reagent Chemicals, Americ

42、an Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary

43、, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.FIG. 1 Schematic of an OFIDD5599 1838.4 DopantIf the OFID is so designed, reagent-grade pentane is used as a hydrocarbon dopant for the cracking reactor.(WarningPentane is extremely flammable and harmful when inhaled.)8.5 Instrument GasesTh

44、e gases supplied to the gas chromatograph and detector are:8.5.1 Air, zero grade. (WarningCompressed air is a gas under high pressure and supports combustion.)8.5.2 Hydrogen, pure grade, 99.9 % mol minimum purity. (WarningHydrogen is an extremely flammable gas under highpressure.)8.5.3 Helium or nit

45、rogen 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 compressed gases under high pressure.)8.5.4 Additional purification of the carrier, air, and hydrogen is recommended. Use molecu

46、lar sieves, Drierite, charcoal, or othersuitable agents to remove water, oxygen, and hydrocarbons from the gases.8.6 Sample ContainerGlass vials with crimp-on or screw-down sealing caps with self-sealing polytetrafluoroethylene(PTFE)-faced rubber membranes are used to prepare calibration standards a

47、nd samples for analysis.9. Preparation of Apparatus9.1 Chromatograph and OFIDPlace instrument and detector into operation in accordance with the manufacturersinstructions. Install the capillary column according to Practice E1510. Adjust the operating conditions to provide for separation ofall oxygen

48、ates of interest. Typical conditions used with the column specified in 7.3 are listed in Table 1.9.2 System PerformanceAt the beginning of each day of operation, inject an oxygenate-free gasoline sample into thechromatograph to ensure minimum hydrocarbon response. If hydrocarbon response is detected

49、, the OFID is not operatingeffectively and must be optimized according to the manufacturers instructions before the sample can be analyzed.10. Calibration and Standardization10.1 Retention Time IdentificationDetermine the retention time of each oxygenate component by injecting small amountseither separately or in known mixtures. Table 2 gives typical retention times for the oxygenates eluting from a 60 m methyl siliconecolumn temperature programmed according to conditions given in Table 1. A chromatogram of a blend of oxygenates is gi