1、Designation: D 2942 02 (Reapproved 2008)Standard Test Method forTotal Acid Acceptance of Halogenated Organic Solvents(Nonreflux Methods)1This standard is issued under the fixed designation D 2942; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test
3、method covers the determination of the totalacid acceptance including amine and neutral type (alphaepoxide) stabilizers in halogenated organic solvents.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of thi
4、s 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 Section 7.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 2106 Test Methods for
5、 Determination of Amine AcidAcceptance (Alkalinity) of Halogenated Organic SolventsE 200 Practice for Preparation, Standardization, and Stor-age of Standard and Reagent Solutions for ChemicalAnalysis3. Summary of Test Method3.1 Test Method AThe total acid acceptance is determinedby the reaction of t
6、he sample with a known amount ofhydrochloric acid that has been dissolved in isopropyl alcohol.The excess acid remaining after the reaction with the acidacceptor is then back-titrated with a standardized solution ofsodium hydroxide. The total acid acceptance of the stabilizerscan be calculated and r
7、eported as weight % NaOH.3.2 Test Method BThe acid acceptor content is determinedby gas chromatography or another validated method such asdensity or refractive index and the acid acceptance is calculatedfrom the weight % acid acceptor. Techniques like density andrefractive index are generally suitab
8、le only for two-part sys-tems. The method for the determination of the acid acceptorshould be validated for the sample being analyzed to ensurethere is no interference, particularly from such things as oilsand reaction products when measuring acid acceptance ofproduct that is in use such as vapor de
9、greasers.4. Significance and Use4.1 Solvents that have been depleted in stabilizer contentcan become acidic. Acids can cause corrosion to process andstorage equipment used for halogenated solvents.4.2 Halogenated organic solvents may contain amine type(alkaline, aqueous extractable) acid accepting a
10、dditives, neutraltype (typically epoxide) acid accepting additives or both. Thistest method can determine the combined acid acceptance fromboth types of stabilizers. In addition, if the amine acidacceptance is determined by a separate procedure (see TestMethods D 2106), the amount of neutral acid ac
11、cepting stabi-lizers in a solvent can be calculated from the differencebetween combined and amine acid acceptance values.4.3 This test method may be used by producers and users toverify that a product is complying with acid acceptance productspecifications or by users to monitor the acid accepting a
12、bilityof a solvent in use.5. Test Method A5.1 Apparatus5.1.1 Iodine or Erlenmeyer Flasks 250-mL, with ground-glass stoppers.5.1.2 Burets, 25-mL or 50-mL, graduated to 0.1 mL.5.1.3 Pipet, 10-mL and 25-mL.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherw
13、ise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,1This test method is under the jurisdiction of ASTM Committee D26 onHalogenated Organic Solvents and Fire Extinguishing Agents and is the direc
14、tresponsibility of Subcommittee D26.04 on Test Methods.Current edition approved Jan. 1, 2008. Published March 2008. Originallyapproved in 1971. Last previous edition approved in 2002 as D 2942 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where such specifications are available.3Other gra
16、des may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification
17、D 1193.6.3 Bromophenol Blue Indicator Solution (1.0 g/L)Prepared by dissolving 1.0 g of bromophenol blue in a mixtureof 800 mLof water and 200 mLof denatured ethyl alcohol. ThepH range is 3.0 to 4.6. The color change is from yellow on theacid side to blue-green on the alkaline side.6.4 Hydrochlorina
18、tion Reagent (0.1 N HCl)Prepare bydissolving 4.4 mL of concentrated hydrochloric acid (sp gr1.19) in isopropyl alcohol and diluting to 500 mL withisopropyl alcohol.6.5 Sodium Hydroxide, Standard Solution (0.1 N)Prepareand standardize in accordance with Practice E 200.7. Safety Precautions7.1 Solvent
19、 HazardContact with the skin should beavoided to prevent the removal of natural oils.7.2 Observe the published safety procedures when handlingthe concentrated HCl and NaOH solutions.8. Procedure8.1 BlankPipet 25 mL of hydrochlorination reagent and25 mL of isopropyl alcohol with 25-mL pipets into a 2
20、50-mLErlenmeyer flask. Add 3 drops of bromophenol blue indicatorsolution and titrate to a stable blue-green end point with 0.1 NNaOH solution. Record the millilitres of NaOH solutionrequired as A (see Section 9 for calculation).8.2 SampleTransfer 25 mL of hydrochlorination reagentby means of a 25 mL
21、 pipet to a 250-mL glass-stopperedErlenmeyer flask. Add 10 mL of dry halogenated solvent and25 mL of isopropyl alcohol. Shake the mixture thoroughly andallow to stand at room temperature for 10 min. Add 3 drops ofbromophenol blue indicator solution to the sample flask andtitrate with 0.1 N NaOH solu
22、tion to the blue-green end point.Record the millilitres of NaOH solution required as B (seeSection 9 for calculation).NOTE 1Make sure flask and pipette are dry before running analysis.If turbidity or phase separation occurs, add a small amount of isopropanol.8.3 If the amount of nonamine acid accept
23、ance must beknown, first determine the amine acid acceptance in accor-dance with Test Method D 2106.9. Calculation9.1 Total Acid AcceptanceCalculate the total acid accep-tance as equivalent NaOH in weight % as follows:Equivalent NaOH weight, % 5 A 2 B!N3 0.04 3 100/W (1)where:A = NaOH solution requi
24、red for blank titration (8.1),mL,B = NaOH solution required for sample titration (8.2),mL,N = Normality of NaOH solution,0.04 = G equivalent NaOH per mL of 1 normal solution,andW = sample used (volume in mL 3 specific gravity), g.9.2 Nonamine Acid AcceptanceCalculate the nonamineacid acceptance as e
25、quivalent NaOH in weight % as follows:Equivalent NaOH, weight %5 total acid acceptance 2 amine acid acceptance. (2)10. Precision and Bias10.1 The precision limits of this test method have beendetermined as 0.01 % (equivalent NaOH, weight %).10.2 The bias of this test method has not been determined.1
26、1. Test Method B11.1 Determine the weight % of the acid acceptor (typicallyan epoxide, amines may also contribute acid acceptance)present by a validated method such as gas chromatography,density or refractive index. It will be necessary to calibrate theinstrumentation with known standards of the aci
27、d acceptor.11.2 If the acid acceptor is unknown, it can be identified byGC mass spectroscopy.11.3 Calculate the acid acceptance by the following for-mula:Equivalent NaOH, weight, % 540 X wt % acid acceptorMW(3)where:40 = the molecular weight of NaOH, andMW = the molecular weight of the acid acceptor
28、.12. Precision and Bias12.1 A bias of 102 to 105 % of acid acceptance, as com-pared to determining acid acceptance by Method A is notuncommon as the yield of acid acceptance from the acidacceptor by MethodAis commonly 95 to 98 %. This is actuallydue to a low bias (95 to 98 %) of Method A rather than
29、 highreporting by Method B.12.2 A Relative Standard Deviation of about 0.8 % can beexpected when the weight percent acid acceptor is determinedby gas chromatography. The precision of the acid acceptancewill be the same as the precision of the weight percent acidacceptor.13. Keywords13.1 acid accepta
30、nce; halogenated organic solvents; sol-vents; total acid acceptance3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemic
31、als, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D 2942 02 (2008)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin t
32、his standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must
33、be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of there
34、sponsible 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 ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700,
35、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 2942 02 (2008)3
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