1、Designation: D7423 09 (Reapproved 2014)D7423 16Standard 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
2、 indicates the year 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 Scope*1.1 This test method covers the ga
3、s chromatographic procedure 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 200C.200 C
4、. Oxygenate compounds include, but arenot limited to, those listed in Table 1.The linear working range for oxygenates is 0.500.50 mg mg/kg kg to 100 100 mgmg/kg.kg.1.2 This test method is intended to determine the mass concentration of each oxygenate in the hydrocarbon matrix. Oxygenatecompound iden
5、tification is determined by reference standards 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, associate
6、d with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1265 Practice for Sampling Liquefied Petroleum (LP) Gases, Manua
7、l MethodD1835 Specification 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 f
8、or Determination of Precision 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 Practi
9、ce for Gas Chromatography Terms 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, orb
10、oth, that has been liquefied 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. D41753.3 Definitions of Terms Specific to
11、 This Standard: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.D0.04 on C4 and C5 Hydrocarbons.Current edition approved May 1, 2014Feb. 15, 2016. Published July 2014March 2016. O
12、riginally approved in 2009. Last pervious edition approved in 20092014 asD7423 09.D7423 09 (2014). DOI: 10.1520/D7423-09R14.10.1520/D7423-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolum
13、e information, refer to the standards Document Summary page on the ASTM website.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 made to the previous version. Becauseit may not be technically possible to adequa
14、tely 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 Summary of Changes section appears at the end of this standardCopyright ASTM In
15、ternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.3.1 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
16、 lighter hydrocarbons in boiling point 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 configur
17、ation equipped with a valve connected 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 Dea
18、ns switching method equipped with a split 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
19、 configuration might not provide the 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 hydroca
20、rbon mixtures. This technique usinga 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 inlet
21、representative aliquot of sample is injected 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 oxygena
22、te compounds elute from theanalytical 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 col
23、umn.3.4.7 WCOTwall coated open tubular 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 inle
24、t. The on-column valve directinject technique 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 detecto
25、r response. The concentration of each 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 10.66
26、Methyl tert-butyl ether (MTBE) 10.92Diisopropyl 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
27、 alcohol and isopropanol 19.20 (co-elution)Allyl Alcohol 20.00Isobutanol, Tert-butyl alcohol, Sec-Butanol 20.24 (co-elution)N-butanol 20.84D7423 1625. Significance and Use5.1 The determination of oxygenates is important in the manufacture of ethene, propene, 1-3 butadiene, C4 hydrocarbons, andC5 hyd
28、rocarbons. Alcohols, ethers, aldehydes, 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 of
29、0.010.01 mg mg/kg. kg. The gas chromatograph must be capable of linear temperature control from 5050 C to 320C320 C forthe capillary column oven. The gas chromatograph must be capable of controlling multiple valve events. Carrier gas flowcontrollers and or electronic pressure control modules shall b
30、e capable of precise control where the required flow rates are low (seeTable 2). Pressure control devices and gages shall be capable of precise control for the typical pressures required. The temperatureprogram rate must repeat to within 0.1C0.1 C and provide retention time repeatability of 0.05 min
31、 0.05 min throughout thetemperature program.6.2 Carrier Gas Preparation: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
32、 this column. Therefore carriergas filters or the use of any device 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 f
33、or the most accurate results from this test method.6.2.2 Carrier Gas 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 bet
34、ter chromatographic efficiency and selectivity to that described in 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
35、study referred to in Section16.6.4 Polar (Analytical) ColumnThis column 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 bette
36、r chromatographic efficiency and selectivity to that described in 6.4.1 can be used.6.4.1 Oxygenates PLOT column, 10 m 10 m long by 0.53 mm 0.53 mm inside diameter, with a stationary phase composed ofa barium sulfate adsorbent mixture, coated onto a fused silica column. At a minimum the column shoul
37、d have sufficient retentionfor methanol that it elute after n-tridecane (RI 1300) and must have sufficient efficiency and capacity to resolve the oxygenateslisted in Table 1 to provide accurate quantitative results equivalent to those shown in Section 16.Acolumn of this description wasused in the re
38、peatability study referred to in Section 16.6.5 Sample Introduction:TABLE 2 Chromatographic 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 50
39、0 2 500 2Injector, C Not Applicable 250 250Split Ratio Not Applicable 1:1 - xA 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
40、, mL/min 5 5 5Analytical Column Flow, mL/min 7 7 7Needle Valve 1 Flow, mL/min 15 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 mi
41、nimum detection requirements.B Detector RangeAdjust the detector range to a setting which shall provide sufficient voltage to assure the detection of small concentrations of each oxygenate but asto avoid detector signal saturation.D7423 1636.5.1 Switching ValveA valve with an operating temperature o
42、f 225C225 C and operating pressure of 27.57 bar, 27.57 bar,to be located within a heated enclosure or in the main oven. The valve shall be of low volume design and not contributesignificantly to chromatographic deterioration.6.5.2 Liquid Sampling ValveA valve with an operating temperature of 75C75 C
43、 and operating pressure of 68.94 bar,68.94 bar, to be located outside of the oven and used in sampling propane concentrates, butane samples or other LPG samples. Therepeatability of this test is dependent upon a consistent cylinder pressure. It is strongly suggested that the use of a floating piston
44、cylinder be used and that the sample be pressurized to 13.78 bar above the vapor pressure of the sample prior 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 ValveA valve wit
45、h an operating temperature of 225C225 C and operating pressure of27.57 bar to be placed in a heated enclosure maintained at approximately 150C150 C and used to sample ethene vapor. Anexternal sample loop is installed on this valve. A 1000 L sample loop has been used successfully. The sample loop sam
46、ple sizeshall be sized experimentally to provide desired detection limits. This valve must reproduce to within 5 percent relative standarddeviation on each component.6.5.5 Heated Valve EnclosureAny enclosure capable of maintaining the valve and sample loop at 150C.150 C.6.5.6 Connecting TeesAny tees
47、 that can provide an inert connection.6.5.7 TubingAny tubing capable of providing an inert connection.6.5.8 Needle ValveMicrometering valve capable of low flow control 22 mLmin to 90 90 mLmL/min.min.6.6 Data AcquisitionAny computerized data acquisition system shall be used for peak area integration
48、and graphicpresentation of the chromatogram.Alternatively any integrator system can also be used for chromatographic peak area integration.7. Reagents and Materials7.1 Purity of ReagentsBefore preparing the calibration standards, determine the purity of the oxygenate stocks and makecorrections for t
49、he 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.7.3 Compressed HydrogenLess than 11 mg mg/kg kg hydrocarbon impurities for FID fuel gas.7.4 Compressed HeliumGas purity 99.999 %. Note that helium supplies o
