1、Designation: D7423 16aD7423 17Standard Test Method forDetermination of Oxygenates in C2, C3, C4, and C5Hydrocarbon Matrices by Gas Chromatography and FlameIonization Detection1This standard is issued under the fixed designation D7423; the number immediately following the designation indicates the ye
2、ar oforiginal 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. Scope*1.1 This test method covers the gas chromatographic proce
3、dure for the quantitative determination of organic oxygenates in C2,C3, C4, and C5 matrices by multidimensional gas chromatography and flame ionization detection. This test method is applicablewhen the hydrocarbon matrices have a final boiling point not greater than 200 C. Oxygenate compounds includ
4、e, but are notlimited to, those listed in Table 1. The linear working range for oxygenates is 0.50 mgkg to 100 mgkg.1.2 This test method is intended to determine the mass concentration of each oxygenate in the hydrocarbon matrix. Oxygenatecompound identification is determined by reference standards
5、and column elution retention order.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included 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 u
6、ser of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Prin
7、ciples for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1265 Practice for Sampling Liquefied Petroleum (LP) Gases, Manual MethodD1835 Specification
8、for Liquefied Petroleum (LP) GasesD4175 Terminology Relating to Petroleum Products, Liquid Fuels, and LubricantsD6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-ment System PerformanceD6300 Practice for Determination of Precisio
9、n and Bias Data for Use in Test Methods for Petroleum Products and LubricantsD6849 Practice for Storage and Use of Liquefied Petroleum Gases (LPG) in Sample Cylinders for LPG Test MethodsE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE355 Practice for Gas Chromatography Te
10、rms and Relationships3. Terminology3.1 Additional terminology related to the practice of gas chromatography can be found in Practice E355.3.2 Definitions:3.2.1 liquefied petroleum gas (LPG), na mixture of normally gaseous hydrocarbons, predominantly propane or butane, orboth, that has been liquefied
11、 by compression or cooling, or both, to facilitate storage, transport, and handling. D41753.2.2 oxygenate, nan oxygen-containing ashless organic compound, such as an alcohol or ether, which may be used as a fuelor fuel supplement. D41751 This test method is under the jurisdiction ofASTM Committee D0
12、2 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.D0.04 on C4 and C5 Hydrocarbons.Current edition approved Dec. 1, 2016June 1, 2017. Published January 2017July 2017. Originally approved in 2009. Last pervious edition approved in 2016 asD7423 16
13、D7423 16a.1. DOI: 10.1520/D7423-16A.10.1520/D7423-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This doc
14、ument is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as
15、 appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*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. Unite
16、d States13.3 Definitions of Terms Specific to This Standard:3.3.1 Deans switching methodrepresentative aliquot of sample is injected on-column using a sample valve (or via a gaschromatograph split inlet). The sample passes onto a nonpolar column, which elutes the lighter hydrocarbons in boiling poin
17、t orderto the analytical column and backflushes the heavier hydrocarbons to vent. The oxygenate compounds elute from the analyticalcolumn and are detected via a flame ionization detector.3.3.2 Deans switching method direct injectgas chromatographic valve configuration equipped with a valve connected
18、 directlyto the precolumn. This technique is commonly used for the determination of oxygenates in ethene and propene concentrates. Thisconfiguration provides the lowest detection limits such as those commonly required for ethene and propene concentrates.3.3.3 Deans switching method equipped with a s
19、plit inletgas chromatographic valve configuration equipped with a gaschromatograph split inlet for sample introduction into the precolumn. This configuration is commonly used for the determinationof oxygenates in C5 hydrocarbon mixtures. This technique using this configuration might not provide the
20、detection limits notedin the scope of this test method. If lower detection limits are required, then the user should consider using the on-column valvedirect injection technique.3.3.4 valve cut methodcommonly used for the determination of oxygenates in C4 hydrocarbon mixtures. This technique usinga
21、split inlet might not provide the detection limits noted in the scope of this test method. If lower detection limits are required,then the user should consider using the on-column valve direct injection technique.3.3.5 valve cut method equipped with a split inletrepresentative aliquot of sample is i
22、njected via a gas chromatograph splitinlet for sample introduction into the precolumn. The sample passes onto a nonpolar column, which elutes the lighter hydrocarbonsin boiling point order to the analytical column and the heavier hydrocarbons to vent. The oxygenate compounds elute from theanalytical
23、 column and are detected via a flame ionization detector.3.4 Acronyms:3.4.1 DIPEdiisopropylether.3.4.2 ETBEethyl tert-butylether.3.4.3 MEK2-butanone.3.4.4 MTBEmethyl tert-butylether.3.4.5 TAMEtert-amyl methylether.3.4.6 PLOTporous layer open tubular capillary column.3.4.7 WCOTwall coated open tubula
24、r capillary column.4. Summary of Test Method4.1 This test method shall be configured using either the Deans switching method or the valve cut method. Each method shallbe configured using an on-column valve direct inject technique or a gas chromatograph split inlet. The on-column valve directinject t
25、echnique is configured by connecting the head of the precolumn directly to the injection valve.4.2 The detector response and retention times for each oxygenate peak in a calibration standard is measured and used toexternally calibrate the flame ionization detector response. The concentration of each
26、 oxygenate is calculated by the externalstandard technique. Calibration materials are listed in Table 1.TABLE 1 Oxygenates and Typical Retention TimesComponents Retention Time (min)Dimethyl ether 6.18Diethyl ether 8.44Acetaldehyde 8.89Ethyl tert-butyl ether 10.66Methyl tert-butyl ether (MTBE) 10.92D
27、iisopropyl ether 11.22Propionaldehyde (Propanal) 12.00Tertiary amyl methyl ether (TAME) 13.19Propyl ether 14.00Isobutylaldehyde 14.10Butylaldehyde 14.50Methanol 14.91Acetone 15.39Isovaleraldehyde 16.00Valeraldehyde 16.102-Butanone (MEK) 17.14Ethanol 17.51N-propyl alcohol and isopropanol 19.20 (co-el
28、ution)Allyl Alcohol 20.00Isobutanol, Tert-butyl alcohol, Sec-Butanol 20.24 (co-elution)N-butanol 20.84D7423 1725. Significance and Use5.1 The determination of oxygenates is important in the manufacture of ethene, propene, 1-3 butadiene, C4 hydrocarbons, andC5 hydrocarbons. Alcohols, ethers, aldehyde
29、s, and ketones are trace impurities in these hydrocarbons. Oxygenates decreasecatalyst activity in downstream polymerization processes.6. Apparatus6.1 Gas ChromatographAny gas chromatograph equipped with a flame ionization detector (FID) and having sensitivity of0.01 mgkg. The gas chromatograph must
30、 be capable of linear temperature control from 50 C to 320 C for the capillary columnoven. The gas chromatograph must be capable of controlling multiple valve events. Carrier gas flow controllers and or electronicpressure control modules shall be capable of precise control where the required flow ra
31、tes are low (see Table 2). Pressure controldevices and gages shall be capable of precise control for the typical pressures required. The temperature program rate must repeatto within 0.1 C and provide retention time repeatability of 0.05 min throughout the temperature program.6.2 Carrier Gas Prepara
32、tion:6.2.1 Moisture present in the carrier gas causes chromatographic problems.The oxygenates column has very high retention. Dueto this characteristic, moisture and trace impurities in the carrier gas are trapped at the beginning of this column. Therefore carriergas filters or the use of any device
33、 which can be used to eliminate trace levels of oxygen and water are strongly recommended.Additionally, frequent reconditioning and longer than usual column condition times may be necessary to maintain the performanceof this column for the most accurate results from this test method.6.2.2 Carrier Ga
34、s FiltersOxygen and molecular sieve type moisture filters.6.3 Columns:6.3.1 Nonpolar (Precolumn) ColumnThis column performs a pre-separation of the light hydrocarbon fraction up to andincluding TAME. Any column with equivalent or better chromatographic efficiency and selectivity to that described in
35、 6.3.2 canbe used.6.3.2 WCOT Methyl Silicone Column, 25 m long by 0.53 mm inside diameter fused silica WCOT column with a 1.0 m filmthickness of crosslinked methyl siloxane. A column of this description was used in the repeatability study referred to in Section16.6.4 Polar (Analytical) ColumnThis co
36、lumn performs a separation of the oxygenates from volatile hydrocarbons in the sameboiling point range. The oxygenates and remaining hydrocarbons are backflushed to vent through the nonpolar column. Anycolumn with equivalent or better chromatographic efficiency and selectivity to that described in 6
37、.4.1 can be used.6.4.1 Oxygenates PLOT column, 10 m long by 0.53 mm inside diameter, with a stationary phase composed of a barium sulfateadsorbent mixture, coated onto a fused silica column.At a minimum the column should have sufficient retention for methanol thatit elute after n-tridecane (RI 1300)
38、 and must have sufficient efficiency and capacity to resolve the oxygenates listed in Table 1to provide accurate quantitative results equivalent to those shown in Section 16. A column of this description was used in therepeatability study referred to in Section 16.6.5 Sample Introduction:TABLE 2 Chr
39、omatographic Operating ConditionsParameter Deans Switch (Fig. 1) Deans Switch (Fig. 2) Valve Cut (Fig. 3)Valve 1C Ambient Ambient AmbientValve 1 Sample Size, L 2 2 2Valve 2C 150 150 150Valve 2 Sample Size, L - mL 500 2 500 2 500 2Injector, C Not Applicable 250 250Split Ratio Not Applicable 1:1 - xA
40、1:1 - xABackflush, min 2.0 4.0 2.0 4.0 2.0 4.0Column Oven Standby, C 200 200 200Initial Column Oven, C 50 50 50Initial Hold, min 5 5 5Rate, C/min 10 10 10Final Column Oven, C 240 240 220Final Hold, min 5 5 5Precolumn Flow, mL/min 5 5 5Analytical Column Flow, mL/min 7 7 7Needle Valve 1 Flow, mL/min 1
41、5 15 Not ApplicableNeedle Valve 2 Flow, mL/min 6 6 Not ApplicableDetector, C 300 300 300Detector Range B B BA Split ratio shall be experimentally determined using appropriate gravimetric standards to obtain the desired minimum detection requirements.B Detector RangeAdjust the detector range to a set
42、ting which shall provide sufficient voltage to assure the detection of small concentrations of each oxygenate but asto avoid detector signal saturation.D7423 1736.5.1 Switching ValveA valve with an operating temperature of 225 C and operating pressure of 27.57 bar, to be locatedwithin a heated enclo
43、sure or in the main oven. The valve shall be of low volume design and not contribute significantly tochromatographic deterioration.6.5.2 Liquid Sampling ValveAvalve with an operating temperature of 75 C and operating pressure of 68.94 bar, to be locatedoutside of the oven and used in sampling propan
44、e concentrates, butane samples or other LPG samples. The repeatability of thistest is dependent upon a consistent cylinder pressure. It is strongly suggested that the use of a floating piston cylinder be used andthat the sample be pressurized to 13.78 bar above the vapor pressure of the sample prior
45、 to sampling.6.5.3 Low Pressure Liquid SamplingA valve syringe adapter may be used to sample low vapor pressure liquids such as C5concentrates.6.5.4 Low Pressure Gas Sampling ValveAvalve with an operating temperature of 225 C and operating pressure of 27.57 barto be placed in a heated enclosure main
46、tained at approximately 150 C and used to sample ethene vapor. An external sample loopis installed on this valve. A 1000 L sample loop has been used successfully. The sample loop sample size shall be sizedexperimentally to provide desired detection limits. This valve must reproduce to within 5 perce
47、nt relative standard deviation oneach component.6.5.5 Heated Valve EnclosureAny enclosure capable of maintaining the valve and sample loop at 150 C.6.5.6 Connecting TeesAny tees that can provide an inert connection.6.5.7 TubingAny tubing capable of providing an inert connection.6.5.8 Needle ValveMic
48、rometering valve capable of low flow control 2 mLmin to 90 mLmin.6.6 Data AcquisitionAny computerized data acquisition system shall be used for peak area integration and graphicpresentation of the chromatogram.Alternatively any integrator system can also be used for chromatographic peak area integra
49、tion.7. Reagents and Materials7.1 Purity of ReagentsBefore preparing the calibration standards, determine the purity of the oxygenate stocks and makecorrections for the impurities found. Whenever possible, use stocks of 98 % purity or better. The calibration materials are listedin Table 1.7.2 Calibration Standard MixtureA standard mixture containing known concentrations of each oxygenate listed in Table 1should be prepared gravimetrically. This mixture shall be used as an external calibration standard.7
