ASTM D2593-23

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of the standard as published by ASTM is to be considered the official document.
Designation: D2593 − 19 D2593 − 23
Standard Test Method for
Butadiene Purity and Hydrocarbon Impurities by Gas
Chromatography
This standard is issued under the fixed designation D2593; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers the determination of butadiene-1,3 purity and impurities such as propane, propylene, isobutane,
n-butane, butene-1, isobutylene, propadiene, trans-butene-2, cis-butene-2, butadiene-1,2, pentadiene-1,4, and, methyl, dimethyl,
ethyl, and vinyl acetylene in polymerization grade butadiene by gas chromatography. Impurities including butadiene dimer,
carbonyls, inhibitor, and residue are measured by appropriate ASTM procedures and the results used to normalize the component
distribution obtained by chromatography.
NOTE 1—Other impurities present in commercial butadiene must be calibrated and analyzed. Other impurities were not tested in the cooperative work
on this test method.
NOTE 2—This test method can be used to check for pentadiene-1,4 and other C s instead of Test Method D1088.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For specific warning statements, see 6.1 and 9.3.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of
the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For specific warning statements, see 6.1 and 9.3.
1.3.1 The user is advised to obtain LPG safety training for the safe operation of this test method procedure and related activities.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.D0.04 on C4 and C5 Hydrocarbons.
This test method was adopted as a joint ASTM-IP Standard, IP 194, in 1972.
Current edition approved Dec. 1, 2019March 1, 2023. Published January 2020June 2023. Originally approved in 1967. Last previous edition approved in 20142019 as
D2593 – 93 (2014).D2593 – 19. DOI: 10.1520/D2593-19.10.1520/D2593-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2593 − 23
D1088 Method of Test for Boiling Point Range of Polymerization-Grade Butadiene (Withdrawn 1983)
2.2 Energy Institute Standards:
IP 194 Analysis of Butadiene-1,3 Polymerization Grade
3. Summary of Test Method
3.1 A representative sample is introduced into a gas-liquid partition column. The butadiene and other components are separated
as they are transported through the column by an inert carrier gas. Their presence in the effluent is measured by a detector and
recorded as a chromatogram. The chromatogram of the sample is interpreted by applying component attenuation and detector
response factors to the peak areas or peak heights and the relative concentration determined by relating individual peak response
to total peak response. Impurities including butadiene dimer, carbonyls, inhibitor, and residue are measured by appropriate ASTM
procedures and the results used to normalize the distribution obtained by gas chromatography.
4. Significance and Use
4.1 The trace hydrocarbon compounds listed can have an effect in the commercial use of butadiene. This test method is suitable
for use in process quality control and in setting specifications.
5. Apparatus
5.1 Chromatograph—Any chromatograph having either a thermal-conductivity or flame ionization detector can be used provided
the system has sufficient sensitivity and stability to obtain a recorder deflection of at least 2 mm at signal-to-noise ratio of at least
5:1 for 0.01 % by mass of impurity.
5.2 Column—Any column can be used that is capable of resolving the components listed in 1.1 with the exception of butene-1
and isobutylene, which can be eluted together. The components should be resolved into distinct peaks such that the ratio A/B will
not be less than 0.5 where A is the depth of the valley on either side of peak B and B is the height above the baseline of the smaller
of any two adjacent peaks. In the case where the small component peak is adjacent to a large one, it can be necessary to construct
a baseline of the small peak tangent to the curve as shown in Fig. 1.
5.2.1 A description of columns that meet the requirements of this test method is tabulated in the Appendix. Persons using other
column materials must establish that the column gives results that meet the precision requirements of Section 11.
5.3 Sample Inlet System—Means shall be provided for introducing a measured quantity of representative sample into the column.
Pressure-sampling devices can be used to inject a small amount of liquid directly into the carrier gas. Introduction can also be
accomplished by use of a gas valve to charge the vaporized liquid.
FIG. 1 Illustration of A/B Ratio for Small-Component Peak
The last approved version of this historical standard is referenced on www.astm.org.
Obsolete. Contact Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http://www.energyinst.org.uk.
D2593 − 23
5.4 Recorder—A recording potentiometer with a full-scale deflection of 10 mV or less is suitable for obtaining the chromato-
graphic data. Full-scale response time should be 2 s or less, and with sufficient sensitivity to meet the requirements of 5.1.
NOTE 3—Other methods of recording detector output such as computer-teletype systems can be used instead of a recorder, provided precision requirements
of Section 11 are met.
6. Reagents and Materials
6.1 Carrier Gas—A carrier gas appropriate to the type of detector used should be employed. Helium or hydrogen may be used
with thermal conductivity detectors. Nitrogen, helium, or argon may be used with ionization detectors. The minimum purity of any
carrier should be 99.95 mol %. (Warning—Compressed gas. Hazardous pressure.) (Warning—Hydrogen flammable gas.
Hazardous pressure.)
6.1.1 If hydrogen is used, special safety precautions must be taken to ensure that the system is free from leaks and that the effluent
is properly vented.
6.2 Column Materials:
6.2.1 Liquid Phase—The materials that have been used successfully in cooperative work as liquid phases are listed in Table X1.1.
6.2.2 Solid Support—The support for use in the packed column is usually crushed firebrick or diatomaceous earth. Sieve size will
depend on the diameter of the column used and liquid-phase loading, and should be such as would give optimum resolution and
analysis time. Optimum size ranges cannot be predicted on purely theoretical grounds. For some systems it has been found that
a ratio of average particle diameter to column inside diameter of 1:25 will result in minimum retention time and minimum band
widths.
6.2.3 Tubing Material—Copper, stainless steel, Monel, aluminum, and various plastic materials have been found to be satisfactory
for column tubing. The material must be nonreactive with respect to substrate, sample, and carrier gas and of uniform internal
diameter.
6.3 Hydrocarbons for Calibration and Identification—Hydrocarbon standards for all components present are needed for
identification by retention time and for calibration for quantitative measurements.
NOTE 4—Mixtures of hydrocarbons can be used provided there is no uncertainty as to the identity or concentration of the compounds involved.
7. Preparation of Apparatus
7.1 Column Preparation—The technique used to prepare the column is not critical as long as the finished column produces the
desired separation. Preparation of the packing is not difficult once the support, partitioning liquid, and loading level have been
determined. The following general directions have been found to produce columns of acceptable characteristics.
7.1.1 Weigh out the desired quantity of support, usually twice that required to fill the column.
7.1.2 Calculate and weigh out the required quantity of partitioning agent. Dissolve the partitioning agent in a volume of chemically
inert, low-boiling solvent equal to approximately twice the volume of support.
7.1.3 Gradually add the support material to the solution with gentle stirring.
7.1.4 Slowly evaporate the solvent while gently agitating the mixture until the packing is nearly dry and no free liquid is apparent.
7.1.4.1 Some stationary phases such as benzyl cyanide silver nitrate are susceptible to oxidation and must be protected from
excessive exposure to air during the evaporation and drying steps.
7.1.5 Spread the packing in thin layers on a nonabsorbent surface and air- or oven-dry as required to remove all traces of solvent.
7.1.6 Resieve the packing to remove fines and agglomerates produced in the impregnation step.
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7.1.7 Fill the column tubing with packing by plugging one end with glass wool and pouring the packing into the other end through
a small funnel. Vibrate the tubing continuously over its entire length while filling. When the packing ceases to flow, tap the column
gently on the floor or bench-top while vibrating is continued. Add packing as necessary until no further settling occurs during a
2-min period. Remove a small amount of packing from the open end, plug with glass wool, and shape the column to fit the
chromatograph.
7.2 Chromatograph—Mount the column in the chromatograph and establish the operating conditions required to give the desired
separation (Appendix X1). Allow sufficient time for the instrument to reach equilibrium as indicated by a stable base line. Control
the oven temperature so that it is constant to within 0.5 °C without thermostat cycling which causes an uneven base line. Set the
carrier-gas flow rate, measured with a soap film meter, so that it is constant to within 1 mL ⁄min of the selected value.
8. Calibration
8.1 Identification—Select the conditions of column temperature and carrier gas flow that will give the necessary separation.
Determine the retention time for each compound by injecting small amounts of the compound either separately or in mixtures.
Recommended sample sizes for retention data are 1 μL for liquids and 1 cm or less for gases.
8.2 Standardization—The area under the peak of the chromatogram is considered a quantitative measure of the amount of the
corresponding compound. The relative area is proportional to the concentration if the detector responses of the sample components
are equal. The recommended procedure for quantitative calibration is as follows: with all equipment at equilibrium at operating
conditions, inject constant volume samples of high-purity components. Each compound should be injected at least three times. The
areas of the corresponding peaks should agree within 1 %. When a recorder is used, adjust the attenuation in all cases to keep the
peak on-scale and with a height of at least 50 % of full scale. Measure the area of the peaks by any reliable method (Note 7). To
obtain component weight % response data from the area response of the volume injections, it is necessary to consider the density
and purity of the compounds used for calibration. The average volume area response of each component is divided by the density
multiplied by the weight percent purity of the component as follows:
Mass percent response of component (1)
average component peak area
density ×mass percent purity of component
Component mass% detector correction factors are then obtained by selecting a reference component such as butadiene, and
dividing the individual component mass responses into the reference mass response.
8.2.1 Factors derived on a thermal-conductivity detector using helium-carrier gas are as follows:
Component Mol wt Thermal Weight Factor Weight
Response Factor,
Butadiene-
1,3 = 1.00
Butadiene-1,3 54 80 0.68 1.00
Propane 44 65 0.68 1.00
Propylene 42 63 0.67 0.98
Isobutane 58 82 0.71 1.04
n-Butane 58 85 0.68 1.00
Butene-1 56 81 0.69 1.01
Isobutylene 56 82 0.68 1.00
trans-Butene-2 56 85 0.66 0.97
cis-Butene-2 56 87 0.64 0.94
Propadiene 40 53 0.75 1.10
Methyl acetylene 40 58 0.69 1.01
NOTE 5—Response based on data represented by Messner, A. E., Rosie, D. M., and Argabright, P. A., Analytical Chemistry, Vol 31, 1959, pp. 230–233,
and Dietz, W. A., Journal of Gas Chromatography, Vol 5, No. 2, 1967, pp. 68–71.
8.2.1.1 Although not determined with standards, mass factors of 1.00 (compared to butadiene 1,3 as 1.00) were used for
pentadiene-1,4 butadiene-1,2, dimethyl acety
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