ASTM D4526-20

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Designation: D4526 − 12 D4526 − 20
Standard Practice for
Determination of Volatiles in Polymers by Static Headspace
Gas Chromatography
This standard is issued under the fixed designation D4526; 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 Headspace gas chromatography (GC) involves the determination of volatile components in a polymer solution by gas
chromatography of a vapor phase in thermal equilibrium with the sample matrix. Volatiles in finely ground insoluble polymers can
also be determined with and without an extracting solvent.
1.2 This practice provides two procedures:
1.2.1 Procedure A—Automatic headspace analysis.
1.2.2 Procedure B—Manual injection headspace analysis.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 67.
NOTE 1—There is no known ISO equivalent to this standard.
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:
D883 Terminology Relating to Plastics
D4322 Test Method for Residual Acrylonitrile Monomer Styrene-Acrylonitrile Copolymers and Nitrile Rubber by Headspace
Gas Chromatography (Withdrawn 2010)
E260 Practice for Packed Column Gas Chromatography
E355 Practice for Gas Chromatography Terms and Relationships
E594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
3. Terminology
3.1 General—The units, symbols, and abbreviations used in this test method are in accordance with Terminology D883 and
Practice IEEE/ASTM SI-10.
4. Significance and Use
4.1 For various reasons, one may want to There are various reasons why one would measure the level of unreacted or residual
monomer, water, or other volatile components in a polymer sample.
4.2 Volatiles of interest are often at trace concentrations. Headspace analysis is suited for determination of these trace
components which often cannot be determined by conventional gas chromatography because of sample decomposition or
interferences.
This practice is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
Current edition approved Dec. 15, 2012May 15, 2020. Published December 2012June 2020. Originally approved in 1985. Last previous edition approved in 20072012
as D4526 - 97D4526 - 12.(2007). DOI: 10.1520/D4526-12.10.1520/D4526-20.
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.
The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
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D4526 − 20
4.3 For polymer analysis, sample treatment for headspace analysis is simpler than conventional gas chromatography, where
additional precipitation steps may be are required to prevent polymer contamination of the chromatographic column.
4.4 This headspace practice will be able to determine qualitatively any component with sufficient vapor pressure. It is capable
of yielding semiquantitative results and can be used for relative comparisons between samples.
5. Apparatus
5.1 Gas Chromatograph, equipped with an appropriate detector and backflush valve.
,
5.1.1 For Procedure A, an Automated Headspace Sampler, including backflush capability, thermostated sample tray, and
associated accessories fulfill these requirements while providing for automatic sequential sampling of headspace vapors.
5.1.2 Procedure B requires the following additional equipment:
5.1.2.1 Constant-Temperature Bath, capable of maintaining 90 6 1°C.
5.1.2.2 Gas-Tight Gas Chromatographic Syringes, which can be heated to 90°C for sampling and injection.
5.1.2.3 Valve, 6-port for backflush assembly.
NOTE 2—Appropriate detectors could include the following:
(a) Flame ionization (FID) for general organic volatiles,
(a) Flame ionization (FID) for general organic volatiles,
(b) Electron capture (EC) for halogenated species,
(c) Nitrogen-phosphorous (NPD) for acrylonitrile,
(d) Thermal conductivity (TC) for water,
(e) Hall electroconductivity or photoionization (PID) for vinyl chloride, and
(f) Mass selective detection.
(b) Electron capture (EC) for halogenated species,
(c) Nitrogen-phosphorous (NPD) for acrylonitrile,
(d) Thermal conductivity (TC) for water, and
(e) Hall electroconductivity or photoionization (PID) for vinyl chloride.
5.2 Chromatographic Columns:
4,5
5.2.1 Packed Column Analysis—Column packings found to be useful for residual monomers (for example, acrylonitrile, vinyl
chloride) include Chromosorb or Porapak porous polymer packings, 0.4 % Carbowax 1500 liquid phase on Carbopak C support,
or 0.19 % picric acid on Carbopak C support. Other columns can be used after it is determined that they give the required resolution
and accuracy for the component of interest.
5.2.2 Capillary Column Analysis—Choose a column capable of achieving the required resolution for the components of interest.
,
For example, for acrylonitrile monomer, the column of choice is a Quadrex 007–2, 25m × 0.32–mm internal diameter fused silica.
5.3 Integrator, Integration system, recorder (5–mV full scale), computing integrator or appropriate computer data station and
software capable of measuring and storing peak area data.
5.4 Headspace Vials, septa, ring closures, and vial sealer.
5.5 Analytical Balance, capable of weighing to 60.0001 g.
5.6 Soap Film Flowmeter and Stopwatch, or other means of measuring gas flow rates.
5.7 Pressure Regulators for all required gas cylinders.
5.8 Filter-Dryer Assemblies for each required gas cylinder.
6. Reagents and Materials
6.1 Solvent, Reagent Grade, or Best Available—The solvent shouldshall be free of interferences at the retention time of volatile
compounds determined by this technique. Typical polymer solvents include water, dimethylformamide (DMF), dimethylacetamide
(DMAC), propylene carbonate, and o-dichlorobenzene. These solvents are readily backflushed from most chromatographic
columns.
NOTE 3—Volatile contaminants can often be removed by sparging with an inert gas for 24 to 48 h.
6.2 Nitrogen, oxygen-free.
NOTE 4—Helium may also be used as the carrier gas and argon/methane is the preferred carrier gas for use with electron capture detectors.
6.3 Hydrogen, prepurified, for use with flame ionization detectors.
6.4 Air, breathing or water pumped, for use with flame ionization or nitrogen-phosphorus detectors.
The sole source of supply of the apparatus known to the committee at this time is Perkin-Elmer Corp., Main Ave., Norwalk, CT 06856.Supelco, Inc., P.O. Box 628, 146
S. Water St., Bellefonte, PA 16823.
If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a
meeting of the responsible technical committee, which you may attend.
D4526 − 20
6.5 Standards, best available, for volatile compounds to be analyzed using
...