ASTM D5508-94a(2001)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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e1
Designation: D 5508 – 94a (Reapproved 2001)
Standard Test Method for
Determination of Residual Acrylonitrile Monomer in Styrene-
Acrylonitrile Copolymer Resins and Nitrile-Butadiene
Rubber by Headspace-Capillary Gas Chromatography (HS-
CGC)
This standard is issued under the fixed designation D 5508; 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.
e NOTE—Several sections have been changed editorially in March 2001.
1. Scope 3.2 After completion of the timed equilibration, an aliquot
of the heated headspace gas from each vial is injected into a
1.1 This test method covers the determination of the re-
capillarygas-chromatographiccolumn.Anautomatedinjection
sidual acrylonitrile (RAN) content in nitrile-butadiene rubbers
system is used to effect the transfer. The capillary column will
(NBR), styrene-acrylonitrile (SAN) copolymers, and rubber-
providethechromatographicresolutionnecessarytoisolatethe
modified acrylonitrile-butadiene-styrene (ABS) resins.
AN from other volatiles that may be present. TheAN response
1.2 Any components that can generate acrylonitrile in the
is measured using a nitrogen-specific detector (NPD). The raw
headspace procedure will constitute an interference. The pres-
data signal is converted to a relative RAN concentration
ence of 3-hydroxypropionitrile in latices limits this procedure
through a standard addition calculation.
to dry rubbers and resins.
1.3 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 A measurement of the residual acrylonitrile in nitrile
responsibility of the user of this standard to establish appro-
rubbers (NBR), styrene-acrylonitrile copolymers or ABS ter-
priate safety and health practices and determine the applica-
polymers will determine the polymer’s suitability for various
bility of regulatory limitations prior to use. Specific precau-
applications.
tionary statements are given Note 4 and Note 5.
4.2 Under optimum conditions, the minimum level of de-
NOTE 1—There is no current ISO equivalent test method for residual
tection of RAN in NBR, SAN, orABS terpolymers is approxi-
acrylonitrile (RAN) determinations.
mately 50 ppb.
2. Referenced Documents
5. Apparatus
2.1 ASTM Standards:
5.1 Gas Chromatograph, equipped with a nitrogen-
E 691 Practice for Conducting an Interlaboratory Study to
phosphorus specific detector, backflush valve (see Fig. 1), split
Determine the Precision of a Test Method
injector, and capable of accepting megabore (0.53 mm inside
diameter) fused silica capillary columns. Detector make-up gas
3. Summary of Test Method
is required.
3.1 Two dispersions (in o-dichlorobenzene) are prepared
NOTE 2—The use of a backflush configuration will provide for operat-
and sealed in headspace vials for each polymer; one vial
ing advantages, but its use is optional. Chlorinated solvents quench the
contains the polymer in solvent while the second vial contains
alkali bead in a nitrogen-phosphorous detector, producing a loss of signal.
the polymer, solvent, plus a known standard addition of
While the bead (signal) will recover as the solvent evacuates the detector,
acrylonitrile (AN). Both vials are agitated for a specified time
repeated quenching during a multi-run sequence may produce instabilities
under ambient conditions. After agitation, the vials are ther-
in the signal (and precision) over the sequence period.
mally equilibrated in a constant-temperature bath.
5.2 Automated Headspace Sampler, should have a thermo-
statted sample tray capable of 90°C heating with constant
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
heating times.Automated sampling of the headspace gas in the
and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
sample vials via a heated, constant-volume sample loop or
Current edition approved Oct. 15, 1994. Published December 1994. Originally
pressure balancing sampling mechanism is required. Sampling
published as D 5508 – 94. Last previous edition D 5508 – 94.
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5508
NOTE 5—Warning: o-Dichlorobenzene is moderately toxic and should
only be handled in a hood or with proper personal protection to limit
human exposure.
NOTE 6—Each lot of o-dichlorobenzene should be analyzed under the
same instrumental conditions as the NBR samples to ensure that impuri-
ties are not present that will interfere with the acrylonitrile peak.
7. Sampling and Storage
7.1 The polymer test unit (sample) submitted for analysis
should be supplied in the form of a 1 ⁄4in. (45 mm) cube.
7.2 All test specimens should be taken from the interior of
the polymer-test unit to minimize the contribution of surface
effects on the residual-acrylonitrile level.
FIG. 1 Configuration of Eight-Port Valve Backflush Assembly
7.3 Keep all polymer-test units in sealed containers. Ana-
lyze test-specimen solutions immediately after preparation.
tothegaschromatographshouldbeviaaheatedtransferlineof
Report any analysis delays along with the test results.
minimum dead volume.
5.3 Fused Silica Porous-Layer-Open-Tubular (PLOT) Cap-
8. Calibration
illary Column , GS-Q, 30 m 3 0.53 mm inside diameter.
8.1 Preparation of External Standard Solutions:
NOTE 3—The column should be cut so as to havea3m section for the 8.1.1 Tare (to the nearest 0.1 mg) a 25-mL volumetric flask
pre-column (Column 1) and a 27-m section for the analytical column
containing 10 mL of o-dichlorobenzene (DCB).
(Column 2).
8.1.2 Weigh (to the nearest 0.1 mg) into the 25-mL volu-
metric flask 40 6 5 mg of AN. Dilute to the mark with DCB.
5.4 Variable Restrictor.
5.5 Data-Recording Device—Astrip-chart recorder, record- Label this solution as the “external-standard master solution”.
8.1.3 Add 1 mL of the “external-standard master solution”
ing integrator, or computer-based data system is suitable.
5.6 Wrist-Action Shaker. to a clean 10-mL volumetric flask containing 2 mL of DCB.
Dilute to the mark with additional DCB. Label this solution as
5.7 Balance, analytical, 0.1-mg readability.
5.8 Headspace Vials, 20-mL capacity. the “external-standard working solution”.
8.1.4 Prepare fresh “master” and “working” solutions each
5.9 Aluminum Crimp Caps, 20-mm diameter.
5.10 Septa, TFE-fluorocarbon-faced silicone construction, week and keep refrigerated at 4°C using Parafilm “M” to seal
volumetric stoppers.
20-mm diameter.
5.11 Crimper, for 20-mm crimp caps. 8.2 Generation of the External-Standard Calibration Curve:
NOTE 7—A new external-standard calibration curve should be gener-
6. Reagents and Materials
atedeachweektoaccountforanychangesintheANresponseduetoNPD
6.1 Purity of Reagents—Chemicals of the highest purity
bead fluctuations.
shall be used in all tests. Solvents should have a minimum of
8.2.1 Transfer 5 mL of DCB into seven clean headspace
volatile impurities. Other grades should only be used after
vials, using a volumetric pipet.
ascertaining that the reagent is free of interferences.
8.2.2 Add 0 (solvent blank), 1, 5, 10, 20, 60, or 100 µL of
6.2 Observe all health and safety recommendations for each
the “external-standard working solution”, respectively, to the
chemical, as prescribed by the manufacturer.
vials.
6.3 Acrylonitrile, 99+%.
8.2.3 Seal each vial immediately after addition with a
NOTE 4—Warning: Acrylonitrile is an OSHA-regulated carcinogen septum and crimp cap.
and should not be released into the laboratory atmosphere. All work
8.2.4 Establish the instrument parameters as listed inAnnex
involving acrylonitrile should be carried out in a hood or with proper
A1.
personal protection to minimize human exposure.
8.2.5 Obtain the peak-area values for AN in each of the
6.4 o-Dichlorobenzene.
standards.
9. Procedure
J & W Scientific Catalog Number 115-3432, available from J & W Scientific,
9.1 Determine the Target AN Weight for Polymer Test Units:
91 Blue Ravine Road, Folsom, CA 95630-4714, or equivalent, has been found
suitable for this purpose.
9.1.1 Weigh (to the nearest 0.1 mg) into a clean headspace
PE Number N930-2823, available from PE XPRESS, Perkin-Elmer Corp., 761
vial 400 6 10 mg of polymer. Add 5 mL of DCB, using a
MainAve.,Norwalk,CT06859-0156,orequivalent,hasbeenfoundsuitableforthis
volumetric pipet. Seal vial with septum and crimp cap.
purpose.
Mettler AE163, available from Mettler-Toledo, Inc., 1900 Polaris Pkwy, 9.1.2 Place the vial on a wrist-action shaker, set at maxi-
Columbus, OH 43420, or equivalent, has been found suitable for this purpose.
mum agitation for 16 h under ambient conditions.
Aldrich Catalog Number 11 021-3, available fromAldrich Chemical Co., 1001
West Saint PaulAve., Milwaukee, WI 53233, or equivalent has been found suitable
for this purpose.
B & J Brand, available from VWR Scientific Products, 1310 Goshen Pkwy,
West Chester, PA19380, Catalog Number 061-4*DK, or equivalent, has been found Available from Pelco International, P.O. Box 492499, Redding, CA
suitable for this purpose. 96049–2477.
D 5508
9.1.3 Analyze the sample under the same instrument param- 9.3.3 Seal vials with crimper (immediately after an addi-
eters as was used to generate the external-standard calibration tion).
curve. 9.3.4 Place the vials on a wrist-action shaker, set at maxi-
9.1.4 Obtain the peak-area value for AN. mum agitation for 16 h under ambient conditions.
9.3.5 Establish the instrument parameters as listed inAnnex
9.2 Preparation of AN Standard-Addition Solution:
A1.
NOTE 8—The following steps in preparing the AN standard addition
9.3.6 Obtain the peak-area values for AN from each vial.
solution are given as an illustration only. Depending on the target weights
involved,theANconcentrationofthesesolutionsmayneedtobea
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