1、Designation: D7796 12 An American National StandardStandard Test Method forAnalysis of Ethyl tert-Butyl Ether (ETBE) by GasChromatography1This standard is issued under the fixed designation D7796; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 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 the purityof ethyl tert-butyl ether (ETBE) by g
3、as chromatography. It alsoprovides a procedure to measure impurities in ETBE such asC4to C12olefins, methyl, isopropyl and tert-butyl alcohols,methyl sec-butyl and methyl tert-amyl ethers, acetone, andmethyl ethyl ketone.1.2 This test method is not applicable to the determinationof ETBE in gasoline.
4、1.3 Water cannot be determined by this test method andshall be measured by a procedure such as Test Method D6304and the result used to normalize the chromatographic values.1.4 Most of the impurities in ETBE are resolved by the testmethod, however, some co-elution is encountered.1.5 This test method
5、is inappropriate for impurities that boilat temperatures higher than 180 C or for impurities that causepoor or no response in a flame ionization detector, such aswater.1.6 The values stated in SI units of measurement arepreferred and used throughout the standard. Alternate units, incommon usage, are
6、 also provided to improve clarity and aid theuser of this test methods.1.7 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 th
7、e applica-bility of regulatory limitations prior to use.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations iss
8、ued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D3700 Practice for Obtaining LPG Samples Using a Float-ing Piston CylinderD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4307 Practice for Preparation of L
9、iquid Blends for Use asAnalytical StandardsD4626 Practice for Calculation of Gas ChromatographicResponse FactorsD6304 Test Method for Determination of Water in Petro-leum Products, Lubricating Oils, and Additives by Cou-lometric Karl Fischer TitrationD7618 Specification for Ethyl Tertiary-Butyl Ethe
10、r (ETBE)for Blending with Aviation Spark-Ignition Engine FuelE355 Practice for Gas Chromatography Terms and Relation-shipsE594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid Chromatography3. Terminology3.1 DefinitionsThis test method makes reference to manycommon g
11、as chromatographic procedures, terms, and relation-ships. Detailed definitions of these can be found in PracticesE355 and E594.3.2 Definitions of Terms Specific to This Standard:3.2.1 C4to C12olefins, ncommon olefin impurities inETBE including unreacted feedstock and dimers or trimers offeed such as
12、 trimethylpentene or pentamethylheptene.4. Summary of Test Method4.1 A representative aliquot of the ETBE product sample isintroduced into a gas chromatograph equipped with a methylsilicon bonded phase fused silica open tubular column. Heliumcarrier gas transports the vaporized aliquot through the c
13、olumnwhere the components are separated by the chromatographicprocess. Components are sensed by a flame ionization detectoras they elute from the column.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibili
14、ty ofSubcommittee D02.04.0L on Gas Chromatography Methods.Current edition approved May 15, 2012. Published November 2012. DOI:10.1520/D7796-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.Copyright ASTM International, 100 Ba
15、rr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom
16、mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14.2 The detector signal is processed by an electronic dataacquisition system or integrating computer. Each eluting com-ponent is identified by comparing its retention time to thoseestablished by analyzing
17、standards under identical conditions.4.3 The concentration of each component in mass percent isdetermined by normalization of the peak areas after each peakarea has been corrected by a detector response multiplicationfactor and the water content of the sample. The detectorresponse factors are determ
18、ined by analyzing prepared stan-dards with the concentrations similar to those encountered inthe sample.5. Significance and Use5.1 The presence of impurities in ETBE product can have adeleterious effect upon the value of ETBE as a fuel additive.Oxygenate and olefin contents are of primary concern. T
19、his testmethod provides a knowledge of the composition of ETBEproduct. This is useful in the evaluation of process operationscontrol, in the valuation of the product, and for regulatorypurposes.6. Interferences6.1 Cyclopentane and 2,3-dimethylbutane have been ob-served to co-elute with MTBE. However
20、, these are not com-monly found impurities in MTBE, and MTBE is typicallypresent at very low concentrations in ETBE.7. Apparatus7.1 Gas ChromatographInstrumentation capable of oper-ating at the conditions listed in Table 1. A heated flashvaporizing injector designed to provide a linear sample spliti
21、njection (that is, 200:1) is required for proper sample intro-duction. Carrier gas controls shall be of adequate precision toprovide reproducible column flows and split ratios in order tomaintain analytical integrity. Pressure control devices andgages shall be designed to attain the linear velocity
22、required inthe column used (for example, if a 150 m column is used, apressure of approximately 550 kPa (80 psig) is required). Ahydrogen flame ionization detector with associated gas controlsand electronics, designed for optimum response with opentubular columns, is required.7.2 Sample IntroductionM
23、anual or automatic liquid sy-ringe sample injection to the splitting injector is employed.Devices capable of 0.1 L to 0.5 L injections are suitable. Itshould be noted that inadequate splitter design, or poorinjection technique, or both, can result in poor resolution.Overloading of the column can als
24、o cause loss of resolution forsome components and, since overloaded peaks are skewed,variation in retention times. Watch for any skewed peaks thatindicate overloading during column evaluation. Observe thecomponent size and where possible, avoid conditions leadingto this problem during the analyses.7
25、.3 Open Tubular Column3This test method utilizes afused silica open tubular column with non-polar methyl sili-cone bonded (cross-linked) phase internal coating such as oneof the following:Column length 50 m 100 m 150 mFilm thickness 0.5 m 0.5 m 1.0 mInternal diameter 0.20 mm 0.25 mm 0.25 mmOther col
26、umns with equal or greater resolving power may beused. A minimum resolution between trans-2-pentene andtert-butanol, and between cis-2-pentene and tert-butanol of 1.3is required. The 150 m column is expected to decrease thelikelihood of co-elution of impurities.7.4 Electronic Data Acquisition System
27、Any data acquisi-tion and integration device used for quantification of theseanalyses shall meet or exceed these minimum requirements:7.4.1 Capacity for at least 50 peaks per analysis,7.4.2 Normalized area percent calculations with responsefactors,7.4.3 Identification of individual components based
28、on re-tention time,7.4.4 Noise and spike rejection capability,7.4.5 Sampling rate for fast (tA.12. Calibration and Standardization12.1 Identify component peaks from a sample analysis bymatching their retention time with the retention time ofreference compounds analyzed under identical conditions.Rel
29、ative retention times for common contaminants in ETBEproducts are listed in Table 2. Analyze mixtures containingthese compounds to verify their retention times. Mixtures usedfor determining retention times may be blended from purecompounds or purchased. Retention times of other suspectedcontaminants
30、 may be established by analyzing mixtures con-taining these materials under identical conditions. A typicalchromatogram of an ETBE product sample, analyzed on the100 meter column that was used to acquire the repeatabilitydata reported below, is shown in Fig. 1. The peaks are indexedto Table 2.12.2 T
31、ypical mass relative response factors are found inTable 2. These response factors shall be verified by analyzinga prepared standard with concentrations similar to thoseencountered in an ETBE product sample and comparing themeasured results with the prepared composition. If the mea-sured composition
32、does not agree with the preparedcomposition, the response factors should be experimentallydetermined in accordance with Practice D4626 by measuringthe response factors of certified blends that have been pur-chased or blends prepared in accordance with Practice D4307.13. Procedure13.1 Set the instrum
33、ent operating variables to the valuesspecified in Table 1 or to a temperature determined to besuitable by the evaluation in Section 11.13.2 When the gas chromatograph has been inoperative formore than 24 h, raise the column temperature to the maximumtemperature used in the method and hold for 20 min
34、 to removecontaminants from the column. Lower the temperature to theinitial method temperature.13.3 Set the recorder or integration device, or both, foraccurate presentation of the data. Set instrumental sensitivitysuch that any component of at least 0.02 % mass will bedetected, integrated, and repo
35、rted.13.4 Inject 0.1 L to 0.5 L of sample into the injection portand start the analysis. Sample size shall follow guidelinesdiscussed in 7.2. Obtain a chromatogram and peak integrationreport.14. Calculation14.1 Identify each peak by matching retention times withknown reference standards or sample co
36、mponents as discussedin 12.1. If a computing integrator is used, examine the report toensure that peaks are properly identified and integrated. It isvery important that all oxygenate peaks be separated fromhydrocarbon peaks and correctly identified since oxygenateshave very different response factor
37、s than hydrocarbons andnormalization is used for quantification.14.2 Obtain the integrated areas of each impurity peak.Multiply each area by its appropriate response factor asdetermined in 12.2 to obtain peak areas corrected for responsedifferences. Use a response factor of 1.00 for unknownimpuritie
38、s.14.3 Obtain the concentration of water in the sample asdetermined by Test Method D6304, or equivalent.14.4 Calculate the mass % of each impurity using Eq 3:mass % impurity = (corrected peak area/total corrected peak area)3(100 2 mass % water) (3)14.5 Calculate the ETBE purity using Eq 4:ETBE purit
39、y, mass % 5 1002 (sum of all impurities from above + water content)(4)14.6 Report the results to two decimal places.15. Precision and Bias15.1 An estimate of the repeatability of this test method wasobtained by conducting twelve replicate tests on each of twosamples of ETBE in a single laboratory. T
40、able 3 contains theresulting repeatability estimates for ETBE purity and for theimpurities listed in the detailed requirements for ETBE (Table1) of Specification D7618.TABLE 2 Relative Retention Times and Response Factors forETBE Impurities, 100 m ColumnNo. ComponentRelativeRetention Time(ETBE = 1)R
41、elativeResponse(Hexane = 1)1 Dimethyl ether 0.577 3.532 Methanol 0.588 2.593 Isobutylene 0.600 1.234 Butane 0.606 1.015 trans-2-Butene 0.612 1.176 cis-2-Butene 0.622 1.267 Ethanol 0.630 2.168 Acetone 0.664 2.059 iso-Pentane 0.670 1.0210 2-Propanol 0.675 1.9511 1-Pentene 0.68712 2-Methyl-1-butene 0.6
42、9513 Diethyl ether 0699 1.7914 n-Pentane 0.702 1.0115 trans-2-Pentene 0.712 1.1216 tert-Butanol 0.717 1.3417 cis-2-Pentene 0.725 1.1418 2-Methyl-2-butene 0.73319 Cyclopentene 0.76520 Methyl tert-butyl ether 0.824 1.4821 2,3-Dimethyl butane 0.83122 2-Methylpentane 0.839 1.0023 2-Butanone (methyl ethy
43、l ketone) 0.855 1.5924 3-Mthylpentane 0.880 0.9225 n-Hexane 0.931 1.0027 Ethyl tert-butyl ether 1.0028 tert-Amyl methyl ether 1.19 1.3329 Butyl ethyl ether 1.25 1.4230 2,2,4-Trimethyl pentane (iso-octane)1.26 0.9731 2,4,4-Trimethyl-1-pentene 1.34 1.0632 2,4,4-Trimethyl-2-pentene 1.40 0.9333 Toluene
44、1.51 0.9634 2,3,4-Trimethyl-2-pentene 1.59 1.00D7796 124NOTE 1Numbers correspond to components in Table 2.FIG. 1 Typical Chromatogram of an ETBE Sample Analyzed on a 100 Meter ColumnD7796 12515.2 An interlaboratory study program to determine theprecision and bias of this test method will be complete
45、d byMarch 2017.16. Keywords16.1 ETBE; ethyl tert-butyl ether; open tubular column gaschromatographyASTM 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 deter
46、mination 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 responsible technical committee and must be reviewed every five years andif not revised, either reapproved or
47、withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that
48、 your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (
49、single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 3 Repeatability Estimates for Selected Impurities and ETBE PuritySample 1 Sample 2Average Std Dev r Average Std Dev rEthanol 0.16 0.0015 0.0043 0.08 0.0009 0.0025Me
