ASTM D2593-93(1998)
(Test Method)Standard Test Method for Butadiene Purity and Hydrocarbon Impurities by Gas Chromatography
Standard Test Method for Butadiene Purity and Hydrocarbon Impurities by Gas Chromatography
SCOPE
1.1 This test method provides for 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 C5>>s instead of Test Method D1088.
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.> For specific hazard statements, see Notes 4, 5, and 9.
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An American National Standard
Designation:D2593–93 (Reapproved 1998)
Designation: 194/74(81)
Standard Test Method for
Butadiene Purity and Hydrocarbon Impurities by Gas
Chromatography
This standard is issued under the fixed designation D 2593; 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 (e) indicates an editorial change since the last revision or reapproval.
This test method was adopted as a joint ASTM-IP Standard in 1972.
1. Scope separated as they are transported through the column by an
inert carrier gas. Their presence in the effluent is measured by
1.1 This test method provides for the determination of
adetectorandrecordedasachromatogram.Thechromatogram
butadiene-1,3 purity and impurities such as propane, propy-
of the sample is interpreted by applying component attenuation
lene, isobutane, n-butane, butene-1, isobutylene, propadiene,
and detector response factors to the peak areas or peak heights
trans-butene-2, cis-butene-2, butadiene-1,2, pentadiene-1,4,
and the relative concentration determined by relating indi-
and, methyl, dimethyl, ethyl, and vinyl acetylene in polymer-
vidual peak response to total peak response. Impurities includ-
ization grade butadiene by gas chromatography. Impurities
ing butadiene dimer, carbonyls, inhibitor, and residue are
includingbutadienedimer,carbonyls,inhibitor,andresidueare
measured by appropriate ASTM procedures and the results
measured by appropriate ASTM procedures and the results
used to normalize the distribution obtained by gas chromatog-
used to normalize the component distribution obtained by
raphy.
chromatography.
NOTE 1—Other impurities present in commercial butadiene must be 4. Significance and Use
calibrated and analyzed. Other impurities were not tested in the coopera-
4.1 The trace hydrocarbon compounds listed can have an
tive work on this test method.
effect in the commercial use of butadiene. This test method is
NOTE 2—This test method can be used to check for pentadiene-1,4 and
suitable for use in process quality control and in setting
other C s instead of Test Method D 1088.
specifications.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Apparatus
responsibility of the user of this standard to establish appro-
5.1 Chromatograph—Any chromatograph having either a
priate safety and health practices and determine the applica-
thermal-conductivity or flame ionization detector can be used
bility of regulatory limitations prior to use. For specific hazard
provided the system has sufficient sensitivity and stability to
statements, see Note 4, Note 5, and Note 9.
obtain a recorder deflection of at least 2 mm at signal-to-noise
ratio of at least 5:1 for 0.01 weight % of impurity.
2. Referenced Documents
5.2 Column—Any column can be used that is capable of
2.1 ASTM Standards:
resolving the components listed in 1.1 with the exception of
D 1088 Test Method for Boiling Point Range of
butene-1 and isobutylene, which can be eluted together. The
Polymerization-Grade Butadiene
componentsshouldberesolvedintodistinctpeakssuchthatthe
ratio A/B will not be less than 0.5 where A is the depth of the
3. Summary of Test Method
valley on either side of peak B and B is the height above the
3.1 A representative sample is introduced into a gas-liquid
baseline of the smaller of any two adjacent peaks. In the case
partition column. The butadiene and other components are
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.
This test method is under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
5.2.1 A description of columns that meet the requirements
D02.D0.04 on C Hydrocarbons.
of this test method is tabulated in theAppendix. Persons using
Current edition approved Feb. 15, 1993. Published April 1993. Originally
other column materials must establish that the column gives
published as D 2593 – 67. Last previous edition D 2593 – 86.
results that meet the precision requirements of Section 11.
Discontinued; See 1984 Annual Book of ASTM Standards, Vol 05.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2593–93 (1998)
satisfactory for column tubing. The material must be nonreac-
tive 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 6—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
FIG. 1 Illustration of A/B Ratio for Small-Component Peak
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 character-
5.3 Sample Inlet System—Means shall be provided for
istics.
introducing a measured quantity of representative sample into
the column. Pressure-sampling devices can be used to inject a
7.1.1 Weigh out the desired quantity of support, usually
small amount of liquid directly into the carrier gas. Introduc-
twice that required to fill the column.
tion can also be accomplished by use of a gas valve to charge
7.1.2 Calculate and weigh out the required quantity of
the vaporized liquid.
partitioning agent. Dissolve the partitioning agent in a volume
5.4 Recorder—A recording potentiometer with a full-scale
ofchemicallyinert,low-boilingsolventequaltoapproximately
deflection of 10 mV or less is suitable for obtaining the
twice the volume of support.
chromatographic data. Full-scale response time should be 2 s
7.1.3 Graduallyaddthesupportmaterialtothesolutionwith
or less, and with sufficient sensitivity to meet the requirements
gentle stirring.
of 5.1.
7.1.4 Slowly evaporate the solvent while gently agitating
NOTE 3—Othermethodsofrecordingdetectoroutputsuchascomputer-
the mixture until the packing is nearly dry and no free liquid is
teletype systems can be used instead of a recorder, provided precision
apparent.
requirements of Section 11 are met.
7.1.4.1 Some stationary phases such as benzyl cyanide
6. Reagents and Materials
silver nitrate are susceptible to oxidation and must be protected
from excessive exposure to air during the evaporation and
6.1 Carrier Gas—A carrier gas appropriate to the type of
drying steps.
detectorusedshouldbeemployed.Heliumorhydrogenmaybe
used with thermal conductivity detectors. Nitrogen, helium, or 7.1.5 Spread the packing in thin layers on a nonabsorbent
argon may be used with ionization detectors. The minimum surface and air- or oven-dry as required to remove all traces of
purity of any carrier should be 99.95 mol %. solvent.
7.1.6 Resieve the packing to remove fines and agglomerates
NOTE 4—Warning: Compressed gas. Hazardous pressure.
produced in the impregnation step.
NOTE 5—Warning: Hydrogen flammable gas. Hazardous pressure.
7.1.7 Fill the column tubing with packing by plugging one
6.1.1 Ifhydrogenisused,specialsafetyprecautionsmustbe
end with glass wool and pouring the packing into the other end
taken to ensure that the system is free from leaks and that the
throughasmallfunnel.Vibratethetubingcontinuouslyoverits
effluent is properly vented.
entirelengthwhilefilling.Whenthepackingceasestoflow,tap
6.2 Column Materials:
the column gently on the floor or bench-top while vibrating is
6.2.1 Liquid Phase—The materials that have been used
continued. Add packing as necessary until no further settling
successfully in cooperative work as liquid phases are listed in
occurs during a 2-min period. Remove a small amount of
Table X1.1.
packingfromtheopenend,plugwithglasswool,andshapethe
6.2.2 Solid Support—The support for use in the packed
column to fit the chromatograph.
column is usually crushed firebrick or diatomaceous earth.
Sieve size will depend on the diameter of the column used and 7.2 Chromatograph—Mount the column in the chromato-
liquid-phase loading, and should be such as would give graph and establish the operating conditions required to give
optimum resolution and analysis time. Optimum size ranges thedesiredseparation(AppendixX1).Allowsufficienttimefor
cannot be predicted on purely theoretical grounds. For some the instrument to reach equilibrium as indicated by a stable
systems it has been found that a ratio of average particle base line. Control the oven temperature so that it is constant to
diameter to column inside diameter of 1:25 will result in within 0.5°C without thermostat cycling which causes an
minimum retention time and minimum band widths. uneven base line. Set the carrier-gas flow rate, measured with
6.2.3 Tubing Material—Copper, stainless steel, Monel, alu- a soap film meter, so that it is constant to within 1 mL/min of
minum, and various plastic materials have been found to be the selected value.
D2593–93 (1998)
8. Calibration conductivity detectors with helium-carrier gas. With other
detectors or carrier gas, or both, it is necessary to calibrate
8.1 Identification—Select the conditions of column tem-
(Note 7).
perature and carrier gas flow that will give the necessary
8.2.2 Measurements can be made using peak heights as
separation.Determinetheretentiontimeforeachcompoundby
criteria for calculations instead of peak areas. If peak heights
injecting small amounts of the compound either separately or
are used, care must be taken so that chromatograph-operating
in mixtures. Recommended sample sizes for retention data are
parameters such as column temperature and carrier-gas flow
1 µL for liquids and 1 cm or less for gases.
rate are kept at the same conditions as when the unit was
8.2 Standardization—The area under the peak of the chro-
calibrated. The chromatograph can be calibrated using known
matogram is considered a quantitative measure of the amount
blends or by establishing relative-response data using peak
of the corresponding compound. The relative area is propor-
heights in the same manner as listed above.
tional to the concentration if the detector responses of the
NOTE 8—Use of a hydrogen-flame detector gives essentially equal
sample components are equal. The recommended procedure
relative response to hydrocarbons. On a weight basis, the sensitivity of the
for quantitative calibration is as follows: with all equipment at
flame detector for hydrocarbons is essentially independent of the hydro-
equilibrium at operating conditions, inject constant volume
carbonsstructure.Onamolarbasis,thesensitivityappearstobeafunction
samples of high-purity components. Each compound should be
of the carbon content, giving essentially equal relative response to
injected at least three times. The areas of the corresponding
hydrocarbons containing the same number of carbon atoms.
peaks should agree within 1 %.When a recorder is used, adjust
8.2.3 Becausedetectororamplifieroutputneednotbelinear
the attenuation in all cases to keep the peak on-scale and with
with component concentration, this must be checked by inject-
a height of at least 50 % of full scale. Measure the area of the
ing constant volumes of pure butadiene at a series of decreas-
peaks by any reliable method (Note 10). To obtain component
ing pressures from ambient down to 20 mm Hg (torr) or by
weight % response data from the area response of the volume
using synthetic standards with vapor sample valves at ambient
injections, it is necessary to consider the density and purity of
or at decreasing pressures or by using synthetic standards with
the compounds used for calibration. The average volume area
liquid sample valves. If on plotting the results the response is
response of each component is divided by the density multi-
linear, then the calibration procedure given above is satisfac-
pliedbytheweightpercentpurityofthecomponentasfollows:
tory. If not, the relative responses of the minor components
Weight percent response of component
must be determined in the linear response region.
average component peak area
9. Procedure
5 (1)
density 3 weight percent purity of component
9.1 Attach the sample cylinder to the instrument-sampling
Component weight percent detector correction factors are
valve so that the sample is obtained from the liquid phase. If
then obtained by selecting a reference component such as
introduction is through a liquid valve the sample cylinders
butadiene, and dividing the individual component weight
should be pressured with a suitable gas, such as helium, to a
responses into the reference weight response.
pressuresufficienttoensurethatsampleflashingdoesnotoccur
8.2.1 Factors derived on a thermal-conductivity detector
inthelinetothesamplingvalveorinthevalveitself.Ifavapor
using helium-carrier gas are as follows:
valve is used, care must be taken to completely vaporize a
Component Mol wt Thermal Weight Factor Weight Fac- small liquid sample, allowing the vapor to flow through the
Response tor,
sample loop at a flow rate of 5 to 10 mL/min until at least ten
Butadiene-
times the volume of the sample loop has been flushed through.
1,3=1.00
Butadiene-1,3 54 80 0.68 1.00
If a vacuum-sampling system is used with a vapor valve, the
Propane 44 65 0.68 1.00
sampleloopshouldbefilledandevacuatedatleasttwicebefore
Propylene 42 63 0.67 0.98
introduction of sample.
Isobutane 58 82 0.71 1.04
n-Butane 58 85 0.68 1.00
9.2 Charge sufficient sample to ensure a minimum of 10 %
Butene-1 56 81 0.69 1.01
recorder deflection for 0.1 % concentration of impurity at the
Isobutylene 56 82 0.68 1.00
trans-Butene-2 56 85 0.66 0.97
most sensitive operating setting of the instrument (for trace
cis-Butene-2 56 87 0.64 0.94
impurities, such as acetylenes, greater sensitivity is needed).
Propadiene 40 53 0.75 1.10
9.3 Using the same conditions as were used for calibration,
Methyl acetylene 40 58 0.69 1.01
record the peaks of all compounds at attenuation or sensitivity
NOTE 7—Response based on data represented by Messner,A. E., Rosie,
settings that allow maximum peak heights.
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.
NOT
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