ASTM D5442-17(2021)
(Test Method)Standard Test Method for Analysis of Petroleum Waxes by Gas Chromatography
Standard Test Method for Analysis of Petroleum Waxes by Gas Chromatography
SIGNIFICANCE AND USE
5.1 The determination of the carbon number distribution of petroleum waxes and the normal and non-normal hydrocarbons in each can be used for control of production processes as well as a guide to performance in many end uses.
5.2 Data resulting from this test method are particularly useful in evaluating petroleum waxes for use in rubber formulations.
SCOPE
1.1 This test method covers the quantitative determination of the carbon number distribution of petroleum waxes in the range from n-C17 through n-C44 by gas chromatography using internal standardization. In addition, the content of normal and non-normal hydrocarbons for each carbon number is also determined. Material with a carbon number above n-C44 is determined by its difference from 100 % by mass and reported as C45+.
1.2 This test method is applicable to petroleum derived waxes, including blends of waxes. This test method is not applicable to oxygenated waxes, such as synthetic polyethylene glycols (for example, Carbowax2), or natural products such as beeswax or carnauba.
1.3 This test method is not directly applicable to waxes with oil content greater than 10 % as determined by Test Method D721.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 consult and establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 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.
General Information
Relations
Standards Content (Sample)
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.
Designation: D5442 − 17 (Reapproved 2021)
Standard Test Method for
Analysis of Petroleum Waxes by Gas Chromatography
This standard is issued under the fixed designation D5442; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the quantitative determination
D721 Test Method for Oil Content of Petroleum Waxes
of the carbon number distribution of petroleum waxes in the
D4307 Practice for Preparation of Liquid Blends for Use as
range from n-C through n-C by gas chromatography using
17 44
Analytical Standards
internal standardization. In addition, the content of normal and
D4626 Practice for Calculation of Gas Chromatographic
non-normal hydrocarbons for each carbon number is also
Response Factors
determined. Material with a carbon number above n-C is
E260 Practice for Packed Column Gas Chromatography
determined by its difference from 100 % by mass and reported
E355 Practice for Gas Chromatography Terms and Relation-
as C .
45+
ships
1.2 This test method is applicable to petroleum derived
3. Terminology
waxes, including blends of waxes. This test method is not
3.1 Definitions of Terms Specific to This Standard:
applicable to oxygenated waxes, such as synthetic polyethyl-
3.1.1 carbon number, n—a number corresponding to the
eneglycols(forexample,Carbowax ),ornaturalproductssuch
number of carbon atoms in a hydrocarbon.
as beeswax or carnauba.
3.1.2 cool on-column injection, n—a sample introduction
1.3 This test method is not directly applicable to waxes with
technique in gas chromatography where the sample is injected
oil content greater than 10 % as determined by Test Method inside the front portion of a partition column at a temperature
D721. at or below the boiling point of the most volatile component in
the sample.
1.4 The values stated in SI units are to be regarded as
3.1.3 low volume connector, n—a metal or glass union
standard. No other units of measurement are included in this
designed to connect two lengths of capillary tubing. Usually
standard.
designed so that the tubing ends are joined with a minimum of
1.5 This standard does not purport to address all of the either dead volume or overlap between them.
safety concerns, if any, associated with its use. It is the
3.1.4 non(normal paraffın)hydrocarbon (NON), n—all other
responsibility of the user of this standard to consult and
hydrocarbon types excluding those hydrocarbons with carbon
establish appropriate safety, health, and environmental prac- atoms in a single length. Includes aromatics, naphthenes, and
tices and determine the applicability of regulatory limitations branched hydrocarbon types.
prior to use.
3.1.5 normal paraffın, n—a saturated hydrocarbon which
has all carbon atoms bonded in a single length, without
1.6 This international standard was developed in accor-
branching or hydrocarbon rings.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
3.1.6 wall coated open tube (WCOT), n—a term used to
Development of International Standards, Guides and Recom-
specify capillary columns in which the stationary phase is
mendations issued by the World Trade Organization Technical coated on the interior surface of the glass or fused silica tube.
Barriers to Trade (TBT) Committee. Stationary phase may be cross-linked or bonded after coating.
4. Summary of Test Method
4.1 Weighedquantitiesofthepetroleumwaxandaninternal
This test method is under the jurisdiction of ASTM Committee D02 on
standardarecompletelydissolvedinanappropriatesolventand
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.04.0H on Chromatographic Distribution Methods.
Current edition approved Oct. 1, 2021. Published November 2021. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 1993. Last previous edition approved in 2017 as D5442 – 17. DOI: contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
10.1520/D5442-17R21. Standards volume information, refer to the standard’s Document Summary page on
Carbowax is a registered trademark of Union Carbide Corp. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5442 − 17 (2021)
TABLE 1 Typical Operating Conditions
6.2 Sample Introduction System—Any system capable of
Column length (m): 25 30 15 introducing a representative sample onto the front portion of a
Column inside 0.32 0.53 0.25
WCOTcolumn may be employed. Cool on-column injection is
diameter (mm):
preferred, however other injection techniques can be used
Stationary phase: DB-1 RTX-1 DB-5
methyl silicone methyl silicone 5 % phenyl methyl provided the system meets the specification for linearity of
silicone
response in 9.6. For cool on-column injection, syringes with
Film thickness (µm): 0.25 0.25 0.25
0.15 mm to 0.25 mm outside diameter needles have been used
Carrier gas: Helium Helium Helium
Carrier flow (mL/min): 1.56 5.0 2.3
successfully for columns 0.25 mm inside diameter or larger
Linear velocity (cm/s): 33 35 60
and standard 0.47 mm outside diameter syringe needles have
Column initial 80 80 80
been used for columns 0.53 mm inside diameter or greater.
temperature (°C):
Program rate (°C/min):10 8 5
6.2.1 Care must be taken that the sample size chosen does
Final temperature (°C):380 340 350
not allow some peaks to exceed the linear range of the detector
Injection technique: cool on-column cool on-column cool on-column
or overload the capacity of the column.
Detector temperature 380 400 375
(°C):
6.3 Column(s)—Any column used must meet the chromato-
Sample size (µL): 1.0 1.0 1.0
graphic resolution specification in 9.5. WCOT columns with
25 m to 30 m lengths and a stationary phase coating of methyl
siloxane or 5 % phenyl methyl siloxane have been successfully
used. Cross-linked or bonded stationary phases are preferred.
introduced into a gas chromatographic column that separates
6.4 Recorder—Arecordingpotentiometerorequivalentwith
the hydrocarbon components by increasing carbon number.
a full-scale deflection of 5 mV or less for measuring the
The column temperature is linearly increased at a reproducible
detector signal versus time. Full scale response time should be
rate until the sample is completely eluted from the column.
2 s or less. Sensitivity and stability should be sufficient to
4.2 The eluted components are detected by a flame ioniza-
generate greater than 2 mm recorder deflection for a hydrocar-
tion detector and recorded on a strip chart or computer system.
bon injection of 0.05 % by mass under the analysis conditions
The individual carbon numbers are identified by comparing the
employed.
retention times obtained from a qualitative standard with the
6.5 Integrator or Computer—Means must be provided for
retention times of the wax sample. The percent of each
integrating the detector signal and summing the peak areas
hydrocarbon number through C is calculated via internal
between specific time intervals. Peak areas can be measured by
standard calculations after applying response factors.
computerorelectronicintegration.Thecomputer,integrator,or
4.3 For samples with final boiling points greater than
gas chromatograph must have the capability of subtracting the
538 °C complete elution of all components may not be
area corresponding to the baseline (blank) from the sample
achieved under the specified conditions. For this reason, the
area, and have the ability to draw the baselines used for peak
C material is determined by summing the concentrations of
45+ area integration.
each individual carbon number through C and subtracting
this total from 100 % by mass.
7. Reagents and Materials
7.1 Carrier Gas—Carrier gas appropriate for the flame
5. Significance and Use
ionization detector. Hydrogen and helium have been used
5.1 The determination of the carbon number distribution of
successfully. The minimum purity of the carrier gas used
petroleumwaxesandthenormalandnon-normalhydrocarbons
should be 99.95 mol %. (Warning—Hydrogen and helium are
in each can be used for control of production processes as well
compressed gases under high pressure. Hydrogen is an ex-
as a guide to performance in many end uses.
tremely flammable gas.)
5.2 Data resulting from this test method are particularly
7.2 n-hexadecane—Hydrocarbon to be added to samples as
useful in evaluating petroleum waxes for use in rubber formu-
an internal standard. Minimum purity of 98 % is required.
lations.
7.3 Standards for Calibration and Identification—Standard
samples of normal paraffins covering the carbon number range
6. Apparatus
(through C ) of the sample are needed for establishing the
6.1 Chromatograph—Any gas chromatographic instrument
retention times of the individual paraffins and for calibration
thatcanaccommodateaWCOTcolumn,equippedwithaflame
for quantitative measurements. Hydrocarbons used for stan-
ionization detector (FID), and that can be operated at the
dards must be greater than 95 % purity.
conditions given in Table 1 may be employed. The chromato-
7.4 Solvent—A liquid (99 % pure) suitable for preparing a
graph should be equipped with a cool on-column inlet (or
quantitative mixture of hydrocarbons and for dissolving petro-
equivalent) for introducing appropriate quantities of sample
leum wax. Cyclohexane has been used successfully.
without fractionation. In addition, the gas chromatograph must
(Warning—Solvents are flammable and harmful if inhaled.)
be capable of generating a chromatogram where the retention
times of an individual peak have retention time repeatability 7.5 Linearity Standard—Prepare a weighed mixture of
within 0.1 min. Refer to Practices E260 and E355 for general n-paraffins covering the range between n-C to n-C and
16 44
information on gas chromatography. dissolve the mixture in cyclohexane. Use approximately equal
D5442 − 17 (2021)
amounts of each of the paraffins and a balance capable of analysis and maintain this temperature for 30 min. Cool the
determining mass to within 1 % of the mass of each compound column temperature to room temperature and connect the
added. It is not necessary to include every n-paraffin in this
remaining column end to the detector. Care must be taken that
mixture so long as the sample contains n-C , n-C , and at
the column terminates as close as possible to the tip of the FID
16 44
least one of every fourth n-paraffin. It will be necessary to
jet. The temperature of the column between the column oven
prepare the standard sample in cyclohexane, so that the normal
and the detector jet must be maintained above the maximum
paraffins are completely dissolved in the solvent. Solutions of
column temperature.
0.01 % by mass n-paraffin have been used successfully. This
9.2 Operating Conditions—Set the chromatographic operat-
sample must be capped tightly, to prevent solvent loss which
ingconditions(seeTable1)andallowthesystemtoachieveall
willchangetheconcentrationofparaffinsinthestandardblend.
temperature setpoints. The recorder, computer or integrating
NOTE 1—Refer to Practice D4307 for details of how to prepare
device should be connected so that a plot of the detector signal
hydrocarbon mixtures.
versus time can be obtained. Make certain that the FID is
7.6 Internal Standard Solution—Prepare a dilute solution of
ignited before proceeding.
internal standard in cyclohexane in two steps as follows:
9.3 Baseline Blank—After conditions have been set to meet
7.6.1 Prepare a stock solution containing 0.5 % by mass
performance requirements, program the column temperature
n-C in cyclohexane by accurately weighing approximately
upward to the maximum temperature to be used. Once the
0.4 g n-C into a 100 mL volumetric flask. Add 100 mL of
cyclohexane and reweigh. Record the mass of n-C to within column oven temperature has reached the maximum
temperature, cool the column to the selected starting tempera-
0.001 g and the mass of solution (cyclohexane and n-C )to
within 0.l g. ture. Without injecting a sample, start the column temperature
7.6.2 Prepare a dilute solution of n-C internal standard by program, the recording device and the integrator. Make two
diluting one part of stock solution with 99 parts of cyclo-
baseline blank runs to determine if the baseline blank is
hexane. Calculate the concentration of internal standard in the
repeatable. If the detector signal is not stable or if the baseline
dilute solution using Eq 1.
blanks are not repeatable, then the column should either be
conditioned further or replaced.
W 100%
ISTD
C 5 3 (1)
ISTD
W 100 9.3.1 Baseline Bleed—Observe the detector response from
S
the blank run on the recorder. Some increase in detector
where:
response will be observed at the upper column temperatures
C = percent by mass n-C internal standard in dilute
ISTD 16
due to stationary phase bleed. Column bleed is acceptable so
solution,
long as the duplicate baseline blank analyses are repeatable.
W = weight of n-C from 7.6.1,
ISTD 16
The baseline should be a smooth curve, free of any chromato-
W = weight of cyclohexane plus n-C from 7.6.1,
s 16
graphic peaks.
100 % = factor to convert weight fraction to percent by
mass, and
9.4 Solvent Blank—Make a 1 µL injection of the cyclo-
100 = dilution factor.
hexanesolventandprogramthecolumnoven.Thesolventisof
suitable purity if there are no detected peaks within the
8. Sampling
retention time range over which the wax samples elute.
8.1 To ensure homogeneity, completely mix the entire wax
9.5 Column Resolution—Check the efficiency of the GC
sample by heating it to 10 °C above the temperature at which
columnbyanalyzing,underconditionsspecifiedin10.2,a1µL
the wax is completely molten and then mix well by stirring.
injection of 0.05 % by mass solution of n-C and n-C in
20 24
Usingacleaneyedropper,transferafewdropstothesurfaceof
cyclohexane.Thecolumnresolutionmustnotbelessthan30as
a clean sheet of aluminum foil, allow to solidify and break into
calculated using Eq 2.
pieces. The wax can either be used directly as described in
Section 11 or placed in a sealed sample vial until ready for use.
2d
R 5 (2)
8.1.1 Aluminum foil usually contains a thin film of oil from 1.699 W11W2
~ !
processing. This
...
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