ASTM D6579-11(2015)
(Practice)Standard Practice for Molecular Weight Averages and Molecular Weight Distribution of Hydrocarbon, Rosin and Terpene Resins by Size-Exclusion Chromatography
Standard Practice for Molecular Weight Averages and Molecular Weight Distribution of Hydrocarbon, Rosin and Terpene Resins by Size-Exclusion Chromatography
SIGNIFICANCE AND USE
5.1 The MW averages and the MWD are important characteristics of a resin. They may be used for a variety of correlations for fundamental studies, processing, or product applications. The MW and MWD values may also be used for production quality control of resins.
5.2 Limitations—Comparison of SEC molecular weight values should be made only if the data were obtained under identical chromatographic conditions.
SCOPE
1.1 This practice covers the determination of apparent molecular weight (MW) averages and molecular weight distributions (MWD) for THF-soluble hydrocarbon, rosin and terpene resins by size-exclusion chromatography (SEC). This technique is not absolute; it requires calibration with standards of known molecular weight. This practice is applicable to resins containing molecular-weight components that have elution volumes falling within the elution volume range defined by polystyrene standards.
Note 1: SEC is also known as gel permeation chromatography (GPC).
1.2 SEC systems employ low-volume liquid chromatography components and columns packed with relatively small (generally 3 to 20 μm) microporous particles. High-performance liquid chromatography instrumentation and automated data handling systems for data acquisition and processing are also required.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D6579 − 11 (Reapproved 2015)
Standard Practice for
Molecular Weight Averages and Molecular Weight
Distribution of Hydrocarbon, Rosin and Terpene Resins by
Size-Exclusion Chromatography
This standard is issued under the fixed designation D6579; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D3016Practice for Use of Liquid Exclusion Chromatogra-
phy Terms and Relationships
1.1 This practice covers the determination of apparent
D6440Terminology Relating to Hydrocarbon Resins
molecular weight (MW) averages and molecular weight distri-
butions (MWD) for THF-soluble hydrocarbon, rosin and ter-
3. Terminology
pene resins by size-exclusion chromatography (SEC). This
3.1 For definitions of size-exclusion chromatography terms,
technique is not absolute; it requires calibration with standards
see Practice D3016.
of known molecular weight. This practice is applicable to
resins containing molecular-weight components that have elu-
3.2 For definition of terpene resin, see Terminology D804.
tion volumes falling within the elution volume range defined
3.3 For definitions of resin terms, see Terminology D6440.
by polystyrene standards.
4. Summary of Practice
NOTE1—SECisalsoknownasgelpermeationchromatography(GPC).
4.1 Inthispractice,adilutesolutionofahydrocarbon,rosin
1.2 SEC systems employ low-volume liquid chromatogra-
or terpene resin sample is injected into a liquid mobile phase
phy components and columns packed with relatively small
containing the same solvent used to prepare the resin solution.
(generally 3 to 20 µm) microporous particles. High-
The mobile phase transports the resin into and through a
performance liquid chromatography instrumentation and auto-
chromatography column (or set of columns connected in
mated data handling systems for data acquisition and process-
series) packed with a rigid or semirigid, porous substrate that
ing are also required.
separates the molecules according to their size in solution. A
1.3 The values stated in SI units are to be regarded as the
detectormonitorstheeluateasafunctionofelutionvolume(or
standard. The values given in parentheses are for information
time). Upon emerging from the column(s), the fractions of
only.
size-separated molecules are detected and their elution vol-
1.4 This standard does not purport to address all of the
umes (or times) and (usually) concentrations recorded.
safety concerns, if any, associated with its use. It is the
Through calibration, the elution volumes (or times) are con-
responsibility of the user of this standard to establish appro-
verted to apparent molecular weights, and various molecular
priate safety and health practices and determine the applica-
weight parameters for the sample resin are calculated from the
bility of regulatory limitations prior to use.
molecular weight/concentration data.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
5.1 The MW averages and the MWD are important charac-
D804Terminology Relating to Pine Chemicals, Including
teristics of a resin. They may be used for a variety of
Tall Oil and Related Products
correlations for fundamental studies, processing, or product
applications. The MW and MWD values may also be used for
production quality control of resins.
This practice is under the jurisdiction of ASTM Committee D01 on Paint and
Related Coatings, Materials, and Applications and is the direct responsibility of
5.2 Limitations—ComparisonofSECmolecularweightval-
Subcommittee D01.34 on Pine Chemicals and Hydrocarbon Resins.
ues should be made only if the data were obtained under
Current edition approved Dec. 1, 2015. Published December 2015. Originally
identical chromatographic conditions.
approved in 2000. Last previous edition approved in 2011 as D6579–11. DOI:
10.1520/D6579-11R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 6. Apparatus
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1 Solvent Reservoir—The solvent reservoir must hold
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. sufficient solvent to ensure consistency of composition for a
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6579 − 11 (2015)
–7 –8
number of analyses. The reservoir should isolate the solvent than10 to10 RIunitandhaveacellvolume≤10µL.Other
from the atmosphere, permit control of the environment in types of detectors may be used.
contact with the solvent, and be inert to the solvent employed.
NOTE 3—The principal disadvantage of the differential refractometer is
Some means of agitation (for example, magnetic stirring) is
that precise control of temperature, pressure, and flow rate is required to
recommended to ensure uniform composition.
maintain a stable signal for an appropriate level of sensitivity. For
–4
example, most organic liquids have a temperature coefficient of 10 RI
6.2 Solvent Pumping System—The principal requirement of
units per K. Consequently, the temperature within the RI detector cell
the pumping system is production of a relatively constant and –4
must be controlled to within 10 °C.
pulseless flow of solvent through the columns. In general, the
6.6 Tubing and Fittings—All tubing between the sample
rate of flow should be adjustable between 0.1 and 5.0 mL/min,
injector and the detector should be no greater than 0.25 mm
and back pressures should not exceed limits specified by the
(0.010 in.) in internal diameter and of sufficient thickness for
column manufacturer. If the elution volume is not being
use at pressures up to 42 MPa. Connecting tubing should be
measured directly or corrected for systematic changes, the
kept as short as possible, and all fittings and connectors must
precision in the flow rate must be at least 60.3% under the
be designed to prevent backmixing and to have low dead
conditions and over the time interval required for running a
volumes.
typical analysis.
6.7 Data Handling Systems—Means must be provided for
6.3 Sample Injector—The purpose of an injection system is
determining chromatographic peak heights or integrated area
to generate a sharply defined zone of solution containing the
segments at prescribed intervals under the chromatogram and
resin when introducing the resin into the flow stream. A
for handling and reporting the data. This can best be accom-
valve-and-loop assembly or any of a number of commercially
plished by means of a computer or a real-time data acquisition
available high-performance liquid chromatography automatic
system with either off-line or on-line data processing.
injection systems can be used for this purpose. It is required
that contribution to band spreading be minimal and that the
NOTE4—DataacquisitionandhandlingsystemsforSEChavenotbeen
injectorbeabletooperateatthebackpressuregeneratedbythe standardized. However, a number of manufacturers provide chromatogra-
phy data systems that include SEC software. Also, some users have
columns.
developed their own specialized software.
6.4 Columns—Stainless steel columns with uniform and
6.8 Recorder/Plotter (Optional—Either a recording potenti-
highly polished inside walls should be used. Columns with
ometer or a printing device connected to a data handling
lengths ranging from 15 to 50 cm, plus special end fittings,
system may be used to plot the chromatographic data. Pen
frits, and connectors designed to minimize dead volume and
response and signal-to-noise ratio should be chosen so that the
back-mixing are recommended. Micro-particulate, semirigid
concentration signal is not appreciably perturbed.
organic gels, and rigid, solid, porous packing materials are
used for SEC. Generally, the packing materials have narrow
6.9 Other Components (Optional)—Special solvent line
particle size distributions, with particle sizes in the range from
filters, pressure monitors, pulse dampers, flowmeters, thermo-
3 to 20 µm. Packing materials are available in a variety of
stated ovens, syphon counters, plotters, raw data storage
shapes and pore sizes. Columns may be packed with particles
systems,software,andsoforth,areoftenincorporatedwiththe
of relatively uniform pore size or with a “mixed bed” of
essential components previously listed.
particles to produce a broad range of pore sizes for polymer
6.10 The interrelationships of the components are shown
separation. If a set of columns is used, it is recommended that
schematicallyinFig.1.Useofadegasserlocatedinthesolvent
the columns be connected, starting from the injector outlet,
reservoir or between the reservoir and pumping system is
from columns having the smallest to those having the largest
recommended to remove air from the solvent.
packing pore size.
6.11 Analytical Balance, sensitive to 60.0001 g.
NOTE 2—Select the number of columns and pore sizes based on the
molecular weight range of the resins being analyzed, and on the degree of
7. Reagents and Materials
resolution required.
6.5 Detectors—The purpose of the detector is to continu- 7.1 Low-MW Standards—Low-MW compounds, such as
ously monitor the concentration of solute eluting from the
toluene, xylene, or o-dichlorobenzene, that are used for deter-
chromatographic column(s). Consequently, the detector must mining plate count, or as internal standards, must be of high
be sufficiently sensitive and respond linearly to the solute
purity.
concentration. Additionally, the detector must not appreciably
7.2 Polystyrene Standards—Unimodal, narrow, MW stan-
distort the concentration gradient in the emerging stream. This
dards that bracket the desired range of the resins being
requirement imposes severe limitations on the volume of
characterized. Selection of a minimum of three standards per
solution available for detection. For example, use of detectors
decade in molecular weight spanning the effective molecular
with cell volumes greater than 15 µL generally will not be
weight range of the column set is recommended.
acceptable for this practice. A differential refractometer has
moderate sensitivity and general utility.The differential refrac- 7.3 Solvent-Tetrahydrofuran (THF)—Stabilized, high pu-
tometer provides a signal proportional to the difference in rity. Depending on the detector used, ultraviolet (UV) grade
refractive index (RI) between the solvent and the column THF may be required, however, caution should be used due to
eluate. The detector should respond to a change of no more the risk of peroxides in unstabilized THF.
D6579 − 11 (2015)
FIG. 1 Schematic of a SEC System
8. Preparation of Apparatus solutions by weighing an aliquot of the standard into a suitable
clean, dry, solvent-resistant stoppered flask or screw-capped
8.1 Assembly—The SEC system shall be assembled as
vial, then add an appropriate amount of solvent from the
showninFig.1andreadiedforoperation.ForcommercialSEC
mobilephasereservoir.Dissolvethestandardatroomtempera-
systems, follow the manufacturers’ guidelines and recommen-
ture.Donotstirorfilterthesolutions.Mixturesoftwoormore
dations for assembly and operation.
narrowMWDpolymerstandardsmaygenerallybepreparedin
8.2 Temperature—An operating temperature is not specified
the same flask.The standards selected for each solution should
in this practice. However, precise control of the temperature of
differ in Mw values by a factor of 10 or greater. However, it is
the components (injection loop, column(s), detector, and con-
recommended that any higher MW polymer standards (MW >
necting tubing) is critical for controlling the reproducibility of
800000 g⁄mol) be prepared as single, more dilute solutions to
the SEC molecular weights and will significantly reduce
reduce problems relating to polymer size in solution and
baseline drift. In addition, the temperature of the previously
concentration during calibration.
mentioned internal components during an analysis must be
NOTE5—Low-molecularweightstandardsmayberesolvedintodistinct
within 3°C of their temperature at calibration.
oligomeric components on high-resolution column sets. In such case, see
8.3 Flow Rate—Follow the column and instrument manu-
the information supplied by the manufacturer for assigning the approxi-
facturers’ recommendations when selecting a flow rate and mate molecular weight to each oligomer peak.
starting the solvent pumping system. A flow rate of 1 6 0.1
9.2 Reference Standard—The same procedure as described
mL/min is suggested, with the pumping system adjusted to
in 9.1 can be used to prepare dilute solutions (0.1% w/v) of
deliver a relatively constant and pulseless flow of eluent from
low-MW materials such as toluene, xylene, or
the detector outlet. Flow rate may be measured by determining
o-dichlorobenzene for determining the column plate count or
eitherthevolumeorweightofsolventelutedoverasufficiently
for use as an internal standard.
long period of time and under suitable conditions to guarantee
a precision of at least 60.3%. Alternatively, an internal NOTE 6—Alternatively, the dissolved oxygen peak may be used as the
reference standard.
standard or control may be used to monitor flow rate. Flow
rates must be determined during calibration and before or after
9.3 Resin Samples—The typical concentration range for
each analysis.
resin solutions is from 0.2 to 1 mg/mL. Solutions are prepared
as described in 9.1, dissolving with a minimum of agitation.
8.4 Detector—Detector settings should provide optimum
Magneticstirringdevicesorlaboratoryshakersmaybeusedto
sensitivity for solute detection without causing undue baseline
aid dissolution, however, excessive shear, temperature or
noise or overloading of the output signal.
ultrasonic devices may cause the polymer to degrade, and
8.5 Data Handling System—Users are advised to follow the
therefore must not be used with this practice. It is a good
recommendations of their computer or data system manufac-
practice to analyze the resin solutions within 24 h of their
turer for setting data acquisition and integration parameters.
preparation.
9. Preparation of Solutions
9.4 Filtration—Itisrecommendedthatallresinsolutionsbe
9.1 PolystyreneStandards—Thetypicalconcentrationrange filtered through membrane filters to remove any materials
for polystyrene standards is from 0.2 to 1 mg/mL. Prepare likely to obstruct the columns and other system components.
D6579 − 11 (2015)
FIG. 2 Measurement of Peak
...
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. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6579 − 11 D6579 − 11 (Reapproved 2015)
Standard Practice for
Molecular Weight Averages and Molecular Weight
Distribution of Hydrocarbon, Rosin and Terpene Resins by
Size-Exclusion Chromatography
This standard is issued under the fixed designation D6579; 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*Scope
1.1 This practice covers the determination of apparent molecular weight (MW) averages and molecular weight distributions
(MWD) for THF-soluble hydrocarbon, rosin and terpene resins by size-exclusion chromatography (SEC). This technique is not
absolute; it requires calibration with standards of known molecular weight. This practice is applicable to resins containing
molecular-weight components that have elution volumes falling within the elution volume range defined by polystyrene standards.
NOTE 1—SEC is also known as gel permeation chromatography (GPC).
1.2 SEC systems employ low-volume liquid chromatography components and columns packed with relatively small (generally
3 to 20 μm) microporous particles. High-performance liquid chromatography instrumentation and automated data handling systems
for data acquisition and processing are also required.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D804 Terminology Relating to Pine Chemicals, Including Tall Oil and Related Products
D3016 Practice for Use of Liquid Exclusion Chromatography Terms and Relationships
D6440 Terminology Relating to Hydrocarbon Resins
3. Terminology
3.1 For definitions of size-exclusion chromatography terms, see Practice D3016.
3.2 For definition of terpene resin, see Terminology D804.
3.3 For definitions of resin terms, see Terminology D6440.
4. Summary of Practice
4.1 In this practice, a dilute solution of a hydrocarbon, rosin or terpene resin sample is injected into a liquid mobile phase
containing the same solvent used to prepare the resin solution. The mobile phase transports the resin into and through a
chromatography column (or set of columns connected in series) packed with a rigid or semirigid, porous substrate that separates
the molecules according to their size in solution. A detector monitors the eluate as a function of elution volume (or time). Upon
emerging from the column(s), the fractions of size-separated molecules are detected and their elution volumes (or times) and
(usually) concentrations recorded. Through calibration, the elution volumes (or times) are converted to apparent molecular weights,
and various molecular weight parameters for the sample resin are calculated from the molecular weight/concentration data.
This practice is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.34 on Pine Chemicals and Hydrocarbon Resins.
Current edition approved June 1, 2011Dec. 1, 2015. Published June 2011December 2015. Originally approved in 2000. Last previous edition approved in 20062011 as
D6579 – 06.D6579 – 11. DOI: 10.1520/D6579-11.10.1520/D6579-11R15.
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
D6579 − 11 (2015)
5. Significance and Use
5.1 The MW averages and the MWD are important characteristics of a resin. They may be used for a variety of correlations
for fundamental studies, processing, or product applications. The MW and MWD values may also be used for production quality
control of resins.
5.2 Limitations—Comparison of SEC molecular weight values should be made only if the data were obtained under identical
chromatographic conditions.
6. Apparatus
6.1 Solvent Reservoir—The solvent reservoir must hold sufficient solvent to ensure consistency of composition for a number of
analyses. The reservoir should isolate the solvent from the atmosphere, permit control of the environment in contact with the
solvent, and be inert to the solvent employed. Some means of agitation (for example, magnetic stirring) is recommended to ensure
uniform composition.
6.2 Solvent Pumping System—The principal requirement of the pumping system is production of a relatively constant and
pulseless flow of solvent through the columns. In general, the rate of flow should be adjustable between 0.1 and 5.0 mL/min, and
back pressures should not exceed limits specified by the column manufacturer. If the elution volume is not being measured directly
or corrected for systematic changes, the precision in the flow rate must be at least 60.3 % under the conditions and over the time
interval required for running a typical analysis.
6.3 Sample Injector—The purpose of an injection system is to generate a sharply defined zone of solution containing the resin
when introducing the resin into the flow stream. A valve-and-loop assembly or any of a number of commercially available
high-performance liquid chromatography automatic injection systems can be used for this purpose. It is required that contribution
to band spreading be minimal and that the injector be able to operate at the back pressure generated by the columns.
6.4 Columns—Stainless steel columns with uniform and highly polished inside walls should be used. Columns with lengths
ranging from 15 to 50 cm, plus special end fittings, frits, and connectors designed to minimize dead volume and back-mixing are
recommended. Micro-particulate, semirigid organic gels, and rigid, solid, porous packing materials are used for SEC. Generally,
the packing materials have narrow particle size distributions, with particle sizes in the range from 3 to 20 μm. Packing materials
are available in a variety of shapes and pore sizes. Columns may be packed with particles of relatively uniform pore size or with
a “mixed bed” of particles to produce a broad range of pore sizes for polymer separation. If a set of columns is used, it is
recommended that the columns be connected, starting from the injector outlet, from columns having the smallest to those having
the largest packing pore size.
NOTE 2—Select the number of columns and pore sizes based on the molecular weight range of the resins being analyzed, and on the degree of resolution
required.
6.5 Detectors—The purpose of the detector is to continuously monitor the concentration of solute eluting from the
chromatographic column(s). Consequently, the detector must be sufficiently sensitive and respond linearly to the solute
concentration. Additionally, the detector must not appreciably distort the concentration gradient in the emerging stream. This
requirement imposes severe limitations on the volume of solution available for detection. For example, use of detectors with cell
volumes greater than 15 μL generally will not be acceptable for this practice. A differential refractometer has moderate sensitivity
and general utility. The differential refractometer provides a signal proportional to the difference in refractive index (RI) between
–7 –8
the solvent and the column eluate. The detector should respond to a change of no more than 10 to 10 RI unit and have a cell
volume ≤10 μL. Other types of detectors may be used.
NOTE 3—The principal disadvantage of the differential refractometer is that precise control of temperature, pressure, and flow rate is required to
–4
maintain a stable signal for an appropriate level of sensitivity. For example, most organic liquids have a temperature coefficient of 10 RI units per K.
–4
Consequently, the temperature within the RI detector cell must be controlled to within 10 °C.
6.6 Tubing and Fittings—All tubing between the sample injector and the detector should be no greater than 0.25 mm (0.010 in.)
in internal diameter and of sufficient thickness for use at pressures up to 42 MPa. Connecting tubing should be kept as short as
possible, and all fittings and connectors must be designed to prevent backmixing and to have low dead volumes.
6.7 Data Handling Systems—Means must be provided for determining chromatographic peak heights or integrated area
segments at prescribed intervals under the chromatogram and for handling and reporting the data. This can best be accomplished
by means of a computer or a real-time data acquisition system with either off-line or on-line data processing.
NOTE 4—Data acquisition and handling systems for SEC have not been standardized. However, a number of manufacturers provide chromatography
data systems that include SEC software. Also, some users have developed their own specialized software.
6.8 Recorder/Plotter (Optional—Either a recording potentiometer or a printing device connected to a data handling system may
be used to plot the chromatographic data. Pen response and signal-to-noise ratio should be chosen so that the concentration signal
is not appreciably perturbed.
D6579 − 11 (2015)
6.9 Other Components (Optional)—Special solvent line filters, pressure monitors, pulse dampers, flowmeters, thermostated
ovens, syphon counters, plotters, raw data storage systems, software, and so forth, are often incorporated with the essential
components previously listed.
6.10 The interrelationships of the components are shown schematically in Fig. 1. Use of a degasser located in the solvent
reservoir or between the reservoir and pumping system is recommended to remove air from the solvent.
6.11 Analytical Balance, sensitive to 60.0001 g.
7. Reagents and Materials
7.1 Low-MW Standards—Low-MW compounds, such as toluene, xylene, or o-dichlorobenzene, that are used for determining
plate count, or as internal standards, must be of high purity.
7.2 Polystyrene Standards—Unimodal, narrow, MW standards that bracket the desired range of the resins being characterized.
Selection of a minimum of three standards per decade in molecular weight spanning the effective molecular weight range of the
column set is recommended.
7.3 Solvent-Tetrahydrofuran (THF)—Stabilized, high purity. Depending on the detector used, ultraviolet (UV) grade THF may
be required, however, caution should be used due to the risk of peroxides in unstabilized THF.
8. Preparation of Apparatus
8.1 Assembly—The SEC system shall be assembled as shown in Fig. 1 and readied for operation. For commercial SEC systems,
follow the manufacturers’ guidelines and recommendations for assembly and operation.
8.2 Temperature—An operating temperature is not specified in this practice. However, precise control of the temperature of the
components (injection loop, column(s), detector, and connecting tubing) is critical for controlling the reproducibility of the SEC
molecular weights and will significantly reduce baseline drift. In addition, the temperature of the previously mentioned internal
components during an analysis must be within 3°C of their temperature at calibration.
8.3 Flow Rate—Follow the column and instrument manufacturers’ recommendations when selecting a flow rate and starting the
solvent pumping system. A flow rate of 1 6 0.1 mL/min is suggested, with the pumping system adjusted to deliver a relatively
constant and pulseless flow of eluent from the detector outlet. Flow rate may be measured by determining either the volume or
weight of solvent eluted over a sufficiently long period of time and under suitable conditions to guarantee a precision of at least
60.3 %. Alternatively, an internal standard or control may be used to monitor flow rate. Flow rates must be determined during
calibration and before or after each analysis.
8.4 Detector—Detector settings should provide optimum sensitivity for solute detection without causing undue baseline noise
or overloading of the output signal.
8.5 Data Handling System—Users are advised to follow the recommendations of their computer or data system manufacturer
for setting data acquisition and integration parameters.
FIG. 1 Schematic of a SEC System
D6579 − 11 (2015)
FIG. 2 Measurement of Peak
D6579 − 11 (2015)
9. Preparation of Solutions
9.1 Polystyrene Standards—The typical concentration range for polystyrene standards is from 0.2 to 1 mg/mL. Prepare solutions
by weighing an aliquot of the standard into a suitable clean, dry, solvent-resistant stoppered flask or screw-capped vial, then add
an appropriate amount of solvent from the mobile phase reservoir. Dissolve the standard at room temperature. Do not stir or filter
the solutions. Mixtures of two or more narrow MWD polymer standards may generally be prepared in the same flask. The standards
selected for each solution should differ in Mw values by a factor of 10 or greater. However, it is recommended that any higher
MW polymer standards (MW > 800 000 g ⁄mol) be prepared as single, more dilute solutions to reduce problems relating to polymer
size in solution and concentration during calibration.
NOTE 5—Low-molecular weight standards may be resolved into distinct oligomeric components on high-resolution column sets. In such case, see the
information supplied by the manufacturer for assigning the approximate molecular weight to each oligomer peak.
9.2 Reference Standard—The same procedure as described in 9.1 can be used to prepare dilute solutions (0.1 % w/v) of
low-MW materials such as toluene, xylene, or o-dichlorobenzene for determining the column plate count or for use as an internal
standard.
NOTE 6—Alternatively, the dissolved oxygen peak may be used as the reference standard.
9.3 Resin Samples—The typical concentration range for resin solutions is from 0.2 to 1 mg/mL. Solutions
...
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