1、Designation: D 4794 94 (Reapproved 2003)Standard Test Method forDetermination of Ethoxyl or Hydroxyethoxyl Substitution inCellulose Ether Products by Gas Chromatography1This standard is issued under the fixed designation D 4794; the number immediately following the designation indicates the year ofo
2、riginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is applicable to the determination ofethox
3、yl or hydroxyethoxyl substitution in cellulose ether prod-ucts by a Zeisel gas chromatographic technique.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concern
4、s, 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. For specific hazardstatements, see Section 5 and Note 3.2. Summary of Test Method2.1
5、 When a cellulose ether containing ethyl or hydroxyethylsubstitutes is allowed to react with hydriodic acid, one mole ofiodoethane is liberated for each mole of ethoxyl or hydroxy-ethoxyl ether substituted on the cellulose chain. The iodoet-hane is extracted in-situ with o-xylene and quantitated by
6、gaschromatography using an internal standard technique. It isrecommended to run duplicate samples.3. Apparatus3.1 Gas Chromatograph with thermal conductivity detectorand heated injection port.3.2 Electronic Integrator.3.3 Columnstainless steel, 1829 mm in length, 3.2 mm inoutside diameter, packed wi
7、th the reagent in 4.6, coiled to fitthe chromatograph used; or equivalent column and packing asappropriate.3.4 Syringe,10L.3.5 Reaction Vials, Caps, and Heating Block.23.6 Syringe, 100 L.3.7 Cover, stainless steel, fabricated to cover the heatingblock.4. Reagents and Materials4.1 Purity of ReagentsR
8、eagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is
9、 first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.4.2 Iodoethane, 99 % minimum.4.3 O-xylene.4.4 Toluene.4.5 Hydriodic Acid, 57 % (sp gr 1.69 to 1.70).4.6 Column Packing, 10 % methyl silicone stationary phaseUSP code
10、 G1 coated on inert diatomite solid support USPcode S1A, 100/120 mesh.5. Hazards5.1 Safety precautions must be taken for handling of hydri-odic acid.5.2 During the reaction, the glass vials are under pressure.Exercise precaution in handling the hot vials.1This test method is under the jurisdiction o
11、f ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved Oct. 1, 2003. Published October 2003. Originallyapproved in 1988. Last previous edition approved in 19
12、94 as D 4794 94 (1998).2The sole source of supply of a heating block, Silli-Therm Heating Module,Reacti-Block 21, Reacti-Vials, and Minnert valve tops, known to the committee atthis time is the Pierce Chemical Company P.O. Box 117, Rockford, IL 611059976.If you are aware of alternative suppliers, pl
13、ease provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For sugge
14、stions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International,
15、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus Preparation and Conditioning6.1 Column (Note 1)Columns are packed with reagentunder vacuum and mechanical vibration using silanized glasswool to contain the packing. Install each in the gas chromato-gra
16、ph to facilitate on column injection. Condition the columnat 200C for 12 h, then allow it to come to equilibrium underthe conditions described below:Oven temperature, C 130 isothermalInjection port temperature, C 200Detector temperature, C 250Detector current, ma 175 maAttenuation 1Polarity ACarrier
17、 gas heliumColumn A, mL/min 30Column B, mL/min 30NOTE 1The conditions used here were determined to be optimum forthe column. Optimum conditions should be determined for each columnon an individual basis.6.2 Integrator:6.2.1 Settings (Note 2):Attenuation 3Chart speed 1.0Peak width 0.04Threshold 4NOTE
18、 2These settings were used with a Hewlett-Packard 3390AIntegrator. Other units may require different settings.6.2.2 Approximate Component Retention Times:Relative Retention Time Component0.38 iodoethane0.59 toluene (internal standard)1.00 o-xylene7. Preparation of Standard Solutions7.1 Internal Stan
19、dard Solution (25 mg toluene/mLo-xylene):7.1.1 Weigh 25.00 6 0.01 g of toluene into a 1000-mLvolumetric flask.7.1.2 Dilute with o-xylene to 1000 mL.7.2 Calibration Standard Solution:7.2.1 Pipet 2.0 mL of 57 % hydriodic acid into a 5-mL vial.7.2.2 Pipet 2.0 mL of the internal standard solution (pre-p
20、ared in 7.1) into the vial and seal with the mininert valve.7.2.3 Weigh the vial and contents to the nearest 0.1 mg.7.2.4 Add 50 L of iodoethane to the vial with a syringe.7.2.5 Weigh and record the amount of iodoethane added.7.2.6 Shake for 30 s and allow to stand for 20 minutes.8. Calibration of E
21、lectronic Integrator8.1 Inject 1.0 L of the upper solvent layer of the standardsolution prepared in 7.2 into the gas chromatograph and recordthe chromatogram.8.1.1 Calibrate the integrator according to the manufactur-ers instructions.8.2 If an integrator is not available peak areas and responsefacto
22、rs can be determined manually as follows:RF 5A 3 w 3 P13 F0.05 3 B 3 P2(1)where:RF = response factor,A = peak height of internal standard (toluene),w = weight of iodoethane, g,P1= purity of iodoethane,F =factor of 0.289 for ethoxylS45156D, 0.391 forhydroxyethoxyl,0.05 = weight of toluene, g,B = peak
23、 height of iodoethane, andP2= purity of toluene.9. Procedure9.1 Specimen Preparation:9.1.1 Dry the specimen at 105C for 1 h and store in adessicator until cool.9.1.2 Weigh 60 to 80 mg of the specimen prepared in dry9.1.1 into a clean, tared 5-mL reaction vial (see 3.5).9.1.3 For a cellulose ether th
24、at is not soluble in o-xylene,add 2.0 mL of the internal standard solution prepared in 7.1 tothe vial.9.1.4 Add 2.0 mL of hydriodic acid to the vial.9.1.5 For a cellulose ether that is soluble in o-xylene,reverse the order of addition of 9.1.3 and 9.1.4.9.1.6 Cap tightly and weigh the vial.9.1.7 Sha
25、ke the specimen for 30 s.9.1.8 Place the vial in a heated block at 180 6 5C for 2 h.NOTE 3Warning: Vials contain a hot corrosive acid under pressure.9.1.9 Remove the vial and cool in the hood to roomtemperature. The specimen will separate into two layers.9.1.10 Reweigh to determine any loss due to l
26、eakage.Discard any specimen with loss greater than 25 mg.9.1.11 Shake the sample vigorously and allow to stand for20 minutes.9.2 Analysis:9.2.1 Enter the weight of the toluene (internal standard) andthe weight of the specimen into the integrator if an integratoris being used.9.2.2 Inject 1.0 L of th
27、e upper layer of the specimen intothe gas chromatograph.10. Calculation10.1 If an integrator is not available, calculate the peak areasand concentrations using the following equation:ethoxyl, % or hydroxyethoxyl, % 5B 3 0.05 3 P23 RFA 3 sample weight g!(2)where:B = peak height of iodoethane,0.05 = w
28、eight of toluene, g,P2= purity of toluene,RF = response factor determined for calibration standardsolution, andA = peak height of toluene.11. Precision and Bias411.1 PrecisionThe relative precision was found to be0.64 % at the 95 % confidence level.4Supporting data is available from ASTM Internation
29、al Headquarters. RequestRR: D01-1058.D 4794 94 (2003)211.2 BiasNo justifiable statement can be made on the biasof the procedure in this test method because no suitablereference material for determining the bias exists.12. Keywords12.1 cellulose ether; ethoxyl or hydroxyethoxyl substitu-tion; gas chr
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31、rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additio
32、nal standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the A
33、STM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 4794 94 (2003)3
