1、Designation: D5508 16Standard Test Method forDetermination of Residual Acrylonitrile Monomer in Styrene-Acrylonitrile Copolymer Resins and Nitrile-ButadieneRubber by Headspace-Capillary Gas Chromatography (HS-CGC)1This standard is issued under the fixed designation D5508; the number immediately foll
2、owing the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test metho
3、d covers the determination of the re-sidual acrylonitrile (RAN) content in nitrile-butadiene rubbers(NBR), styrene-acrylonitrile (SAN) copolymers, and rubber-modified acrylonitrile-butadiene-styrene (ABS) resins.1.2 Any components that can generate acrylonitrile in theheadspace procedure will consti
4、tute an interference. The pres-ence of 3-hydroxypropionitrile in latices limits this procedureto dry rubbers and resins.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of the
5、safety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in 6.3 and 6.4.NOTE 1Ther
6、e is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Test Method3.1 Two dispersions (in o-dichlorobenzene) are preparedand sealed in headspace vials for e
7、ach polymer; one vialcontains the polymer in solvent while the second vial containsthe polymer, solvent, plus a known standard addition ofacrylonitrile (AN). Both vials are agitated for a specified timeunder ambient conditions. After agitation, the vials are ther-mally equilibrated in a constant-tem
8、perature bath.3.2 After completion of the timed equilibration, an aliquotof the heated headspace gas from each vial is injected into acapillary gas-chromatographic column using an automatedinjection system. The capillary column will provide the chro-matographic resolution necessary to isolate the AN
9、 from othervolatiles potentially present. The AN response is measuredusing a nitrogen-specific detector (NPD). The raw data signalis converted to a relative RAN concentration through astandard addition calculation.4. Significance and Use4.1 A measurement of the residual acrylonitrile in nitrilerubbe
10、rs (NBR), styrene-acrylonitrile copolymers or ABS ter-polymers will determine the polymers suitability for variousapplications.4.2 Under optimum conditions, the minimum level of de-tection of RAN in NBR, SAN, or ABS terpolymers is approxi-mately 50 ppb.5. Apparatus5.1 Gas Chromatograph, equipped wit
11、h a nitrogen-phosphorus specific detector, backflush valve (see Fig. 1), splitinjector, and capable of accepting megabore (0.53 mm insidediameter) fused silica capillary columns. Detector make-up gasis required.NOTE 2The use of a backflush configuration will provide foroperating advantages, but its
12、use is optional. Chlorinated solvents quenchthe alkali bead in a nitrogen-phosphorous detector, producing a loss ofsignal. While the bead (signal) will recover as the solvent evacuates thedetector, repeated quenching during a multi-run sequence may produceinstabilities in the signal (and precision)
13、over the sequence period.5.2 Automated Headspace Sampler, shall have a thermost-atted sample tray capable of 90C heating with constantheating times.Automated sampling of the headspace gas in thesample vials via a heated, constant-volume sample loop or1This test method is under the jurisdiction ofAST
14、M Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods andSection D20.70.02 on Chromatography.Current edition approved Sept. 1, 2016. Published September 2016. Originallyapproved in 1994. Last previous edition approved in 2009 as D5508 - 94a(2009)1.D
15、OI: 10.1520/D5508-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at
16、 the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1pressure balancing sampling mechanism is required. Conductsampling to the gas chromatograph by means of a heatedtransfer line of minimum dead volume.5.3 Fused Si
17、lica Porous-Layer-Open-Tubular (PLOT) Cap-illary Column, 30 m 0.53 mm inside diameter.NOTE 3The column should be cut so as to havea3msection for thepre-column (Column 1) and a 27-m section for the analytical column(Column 2).5.4 Variable Restrictor.5.5 Data-Recording DeviceA strip-chart recorder, re
18、cord-ing integrator, or computer-based data system is suitable.5.6 Wrist-Action Shaker.5.7 Analytical Balance, 0.1-mg readability.5.8 Headspace Vials, 20-mL capacity.5.9 Aluminum Crimp Caps, 20-mm diameter.5.10 Septa, TFE-fluorocarbon-faced silicone construction,20-mm diameter.5.11 Crimper, for 20-m
19、m crimp caps.6. Reagents and Materials6.1 Purity of ReagentsChemicals of the highest purityshall be used in all tests. Solvents shall have a minimum ofvolatile impurities. Other grades shall only be used afterascertaining that the reagent is free of interferences.6.2 Observe all health and safety re
20、commendations for eachchemical, as prescribed by the manufacturer.6.3 Acrylonitrile, 99+%. (WarningAcrylonitrile is anOSHA-regulated carcinogen and should not be released intothe laboratory atmosphere. All work involving acrylonitrileshould be carried out in a hood or with proper personalprotection
21、to minimize human exposure.)6.4 o-Dichlorobenzene. (Warningo-Dichlorobenzene ismoderately toxic and should only be handled in a hood or withproper personal protection to limit human exposure.)NOTE 4Each lot of o-dichlorobenzene should be analyzed under thesame instrumental conditions as the NBR samp
22、les to ensure that impuri-ties are not present that will interfere with the acrylonitrile peak.7. Sampling and Storage7.1 The polymer test unit (sample) submitted for analysisshall be supplied in the form of a 134 in. (45 mm) cube.7.2 All test specimens shall be taken from the interior of thepolymer
23、-test unit to minimize the contribution of surfaceeffects on the residual-acrylonitrile level.7.3 Keep all polymer-test units in sealed containers. Ana-lyze test-specimen solutions immediately after preparation.Report any analysis delays along with the test results.8. Calibration8.1 Preparation of E
24、xternal Standard Solutions:8.1.1 Tare (to the nearest 0.1 mg) a 25-mL volumetric flaskcontaining 10 mL of o-dichlorobenzene (DCB).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.Label this solution as the “external-standard master sol
25、ution”.8.1.3 Add 1 mL of the “external-standard master solution”to a clean 10-mL volumetric flask containing 2 mL of DCB.Dilute to the mark with additional DCB. Label this solution asthe “external-standard working solution”.8.1.4 Prepare fresh “master” and “working” solutions eachweek and keep refri
26、gerated at 4C using Parafilm “M” to sealvolumetric stoppers.8.2 Generation of the External-Standard CalibrationCurve:NOTE 5A new external-standard calibration curve should be gener-ated each week to account for any changes in theAN response due to NPDbead fluctuations.8.2.1 Transfer 5 mL of DCB into
27、 seven clean headspacevials, using a volumetric pipet.8.2.2 Add 0 (solvent blank), 1, 5, 10, 20, 60, or 100 L ofthe “external-standard working solution”, respectively, to thevials.8.2.3 Seal each vial immediately after addition with aseptum and crimp cap.8.2.4 Establish the instrument parameters as
28、listed in AnnexA1.8.2.5 Obtain the peak-area values for AN in each of thestandards.9. Procedure9.1 Determine the Target AN Weight for Polymer Test Units:9.1.1 Weigh (to the nearest 0.1 mg) into a clean headspacevial 400 6 10 mg of polymer. Add 5 mL of DCB, using avolumetric pipet. Seal vial with sep
29、tum and crimp cap.9.1.2 Place the vial on a wrist-action shaker, set at maxi-mum agitation for 16 h under ambient conditions.9.1.3 Analyze the sample under the same instrument param-eters as was used to generate the external-standard calibrationcurve.9.1.4 Obtain the peak-area value for AN.9.2 Prepa
30、ration of AN Standard-Addition Solution:NOTE 6The following steps in preparing the AN standard additionsolution are given as an illustration only. Depending on the target weightsinvolved, theAN concentration of these solutions may need to be adjusted.FIG. 1 Configuration of Eight-Port Valve Backflus
31、h AssemblyD5508 1629.2.1 Tare (to the nearest 0.1 mg) a 25-mL volumetric flaskcontaining 10 mL of DCB.9.2.2 Weigh (to the nearest 0.1 mg) into the 25-mL volu-metric flask 165 6 10 mg ofAN. Dilute to the mark with DCB.Label this solution as the “AN master solution”.9.2.3 Add 50 L of the “AN master so
32、lution” to a clean10-mL volumetric flask containing 2 mL of DCB. Dilute to themark with DCB. Label this solution as the “AN workingsolution”. This solution has an AN concentration of 33 ng/L.9.2.4 Prepare fresh “master” and “working” solutionsweekly or as needed for varying target levels. Keep refri
33、geratedat 4C using Parafilm “M” to seal volumetric stoppers.9.3 Determination of the RAN Concentration:NOTE 7At this point, it must be decided which type of determinationis required: (1) Linearity TestRequired for each different polymer typeas it is encountered. Once the linearity of the standard ad
34、dition has beenestablished it may be assumed valid for further analyses for that specificpolymer type. (2) Precision TestRequired for each different polymertype as it is encountered. Once the precision of the standard addition hasbeen established it may be assumed valid for further analyses for that
35、specific polymer type. (3) Routine Test Both linearity and precisionhave been established for the specific polymer type to be tested. Only aroutine RAN determination is required.9.3.1 Weigh (to the nearest 0.1 mg) into a clean headspacevial 400 6 10 mg of polymer. Add 5 mL of DCB to the vial,using a
36、 volumetric pipet. Loosely place the septum and crimpcap on the vial. Do not seal at this time.9.3.1.1 For a Linearity TestPrepare eight vials with theidentical weight (65 mg) of polymer in each vial.9.3.1.2 For a Precision TestPrepare a minimum of twelvevials with the identical weight (65 mg) of po
37、lymer in eachvial.9.3.1.3 For a Routine TestPrepare two vials per polymertest specimen with the identical weight (65 mg) of polymer ineach vial.9.3.2 Add to each vial a volume of the “AN workingsolution,” resulting in a weight of AN based on the targetweight as specified below for each test.9.3.2.1
38、For a Linearity TestAdd 0, 0.25, 0.5, 1, 2, 3, 4, andfive times the target AN weight to the vials, respectively.9.3.2.2 For a Precision TestMake no addition to six vialsand an addition of three times the targetAN weight to the othersix vials.NOTE 8This group of vials is to be run as six sets each co
39、ntaining onefrom the null addition and three times the target weight. The pairing iscarried through the calculations.9.3.2.3 For a Routine TestMake no addition to one vialand an addition of three times the target AN weight to theremaining vial.9.3.3 Seal vials with crimper (immediately after an addi
40、-tion).9.3.4 Place the vials on a wrist-action shaker, set at maxi-mum agitation for 16 h under ambient conditions.9.3.5 Establish the instrument parameters as listed in AnnexA1.9.3.6 Obtain the peak-area values for AN from each vial.10. Calculations10.1 External-Standard-Calibration Curve:10.1.1 Pl
41、ot AN added (ng) versus AN peak area (seven datapoints obtained from 8.2.5).10.1.2 Perform a linear regression on the data set. Theinverse of the slope, 1/slope, will be the AN-response factorwith units of ng/unit area.10.2 Target AN weight:10.2.1 Calculate the targetAN weight in ng for the polymer:
42、TW, ng! 5 Asp! 3 RF (1)where:A(sp) = peak area for AN in polymer test specimen (from9.1.4), andRF = external-response factor for AN from the external-calibration curve in ng/unit area (from 10.1.2).10.3 RAN Concentration:10.3.1 Linearity Test:10.3.1.1 Plot AN added (ng) versus AN peak area (eightdat
43、a points obtained from 9.3.6) to obtain a curve as illustratedin Fig. 2.10.3.1.2 Perform a linear regression on the data set. Thecorrelation coefficient will determine the degree of linearity forthe specific polymer type. The absolute value of the x-interceptwill give the weight of AN in the polymer
44、.NOTE 9The degree of linearity increases as the correlation coefficientnears a value of 1.10.3.1.3 Calculate the RAN concentration for the polymerin parts per billion (ng/g):RAN, ppb! 5?x 2 intercept?Wsp!(2)where:|x intercept| = absolute value of the x-intercept obtainedfrom the linear regression (n
45、anograms), andW(sp) = weight (grams) of NBR (polymer).FIG. 2 Plot of Detector Response Versus Nanograms Acryloni-trileAddedD5508 16310.3.2 Precision Test:10.3.2.1 PlotAN added (ng) versusAN peak-area values forthe six pairs of data points obtained from 9.3.6. Six lines willbe plotted.10.3.2.2 Perfor
46、m a linear regression on each of the six pairsof data points. Determine the x-intercept for each pair (sixvalues total).10.3.2.3 Calculate the RAN concentration using eachx-intercept value. Refer to 10.3.1.3.10.3.2.4 Calculate the mean for the six RAN values ob-tained above. Determine the standard d
47、eviation (s) for the dataset. The precision will be expressed as the percent relativestandard deviation (%RSD).%RSD 5smean RAN value3100 (3)10.3.3 Routine Test:10.3.3.1 Plot AN added (ng) versus AN peak area values(two points obtained from 9.3.6).10.3.3.2 Perform a linear regression on the data set.
48、 Theabsolute value of the x-intercept will be the weight (ng) of ANin the polymer.10.3.3.3 Calculate the RAN concentration for the polymerin parts per billion (ng/g). Refer to 10.3.1.3.11. Report11.1 Report parts per billion (ng/g) residual acrylonitrilemonomer.12. Precision and BiasNOTE 10Data were
49、 generated only for nitrile rubbers, althoughcomparable repeatability can be expected for SAN and ABS resins.12.1 Precision statements were prepared in accordance withPractice E691.12.2 Ten materials (NBRs) of varying levels of the testcomponent were used in the interlaboratory program. Materials“A” through “E” were 30 to 37 % AN NBRs, and materials“A” through “E” were 40 to 48 % AN NBRs. Testing wasconducted in four laboratories.12.3 No valid statement of between-laboratories reproduc-ibility is acceptable for data from less than six laborato
