1、Designation: D2942 02 (Reapproved 2018)Standard Test Method forTotal Acid Acceptance of Halogenated Organic Solvents(Nonreflux Methods)1This standard is issued under the fixed designation D2942; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This tes
3、t method covers the determination of the totalacid acceptance including amine and neutral type (alphaepoxide) stabilizers in halogenated organic solvents.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does
4、 not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionar
5、y statements are given in Section 7.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Tra
6、de Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD2106 Test Methods for Determination of Amine AcidAcceptance (Alkalinity) of Halogenated Organic SolventsE200 Practice for Preparation, Standardization, and Stor
7、ageof Standard and Reagent Solutions for Chemical Analysis3. Summary of Test Method3.1 Test Method AThe total acid acceptance is determinedby the reaction of the sample with a known amount ofhydrochloric acid that has been dissolved in isopropyl alcohol.The excess acid remaining after the reaction w
8、ith the acidacceptor is then back-titrated with a standardized solution ofsodium hydroxide. The total acid acceptance of the stabilizerscan be calculated and reported as weight % NaOH.3.2 Test Method BThe acid acceptor content is determinedby gas chromatography or another validated method such asden
9、sity or refractive index and the acid acceptance is calculatedfrom the weight % acid acceptor. Techniques like density andrefractive index are generally suitable only for two-part sys-tems. The method for the determination of the acid acceptorshould be validated for the sample being analyzed to ensu
10、rethere is no interference, particularly from such things as oilsand reaction products when measuring acid acceptance ofproduct that is in use such as vapor degreasers.4. Significance and Use4.1 Solvents that have been depleted in stabilizer contentcan become acidic. Acids can cause corrosion to pro
11、cess andstorage equipment used for halogenated solvents.4.2 Halogenated organic solvents may contain amine type(alkaline, aqueous extractable) acid accepting additives, neutraltype (typically epoxide) acid accepting additives or both. Thistest method can determine the combined acid acceptance frombo
12、th types of stabilizers. In addition, if the amine acidacceptance is determined by a separate procedure (see TestMethods D2106), the amount of neutral acid accepting stabi-lizers in a solvent can be calculated from the differencebetween combined and amine acid acceptance values.4.3 This test method
13、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 abilityof a solvent in use.5. Test Method A5.1 Apparatus:5.1.1 Iodine or Erlenmeyer Flasks, 250 mL, with ground-glass stoppers.5.1.2 Burets, 25
14、 mL or 50 mL, graduated to 0.1 mL.5.1.3 Pipet, 10 mL and 25 mL.1This test method is under the jurisdiction of ASTM Committee D26 onHalogenated Organic Solvents and Fire Extinguishing Agents and is the directresponsibility of Subcommittee D26.04 on Test Methods.Current edition approved July 1, 2018.
15、Published July 2018. Originally approvedin 1971. Last previous edition approved in 2013 as D2942 02(2013). DOI:10.1520/D2942-02R18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
16、tion, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization
17、 established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwis
18、e 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 first ascertained that the reagent is ofsufficiently high purity
19、 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 D1193.6.3 Bromophenol Blue Indicator Solution (1.0 g/L)Prepare by dissolving 1.0 g of bromophen
20、ol 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 Hydrochlorination Reagent (0.1 N HCl)Prepare bydissolving 4.4 mL of concentrated hydrochloric acid (sp gr1.19)
21、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 E200.7. Safety Precautions7.1 Solvent HazardContact with the skin should beavoided to prevent the removal of natural oils.7.2 Observe th
22、e 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 250-mLErlenmeyer flask. Add 3 drops of bromophenol blue indicatorsolution and titrate to a stable bl
23、ue-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 pipet to a 250-mL glass-stopperedErlenmeyer flask. Add 10 mL of dry halogenated solvent and25 mL o
24、f 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 solution to the blue-green end point.Record the millilitres of NaOH solution required as B (seeSection
25、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 acceptance must beknown, first determine the amine acid acceptance in accor-dance with Test Methods D2106
26、.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!N 30.04 3100#/W (1)where:A = NaOH solution required for blank titration (8.1), mL,B = NaOH solution required for sample titration (8.2),mL,N = Norm
27、ality of NaOH solution,0.04 = G equivalent NaOH per mLof 1 normal solution, andW = sample used (volume in mL specific gravity), g.9.2 Nonamine Acid AcceptanceCalculate the nonamineacid acceptance as equivalent NaOH in weight % as follows:Equivalent NaOH, weight % (2)5 total acid acceptance 2 amine a
28、cid acceptance.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.11. Test Method B11.1 Determine the weight % of the acid acceptor (typicallyan epoxide, amines may al
29、so 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 acid acceptor.11.2 If the acid acceptor is unknown, it can be identified byGC mass spectroscopy.11.3 Ca
30、lculate 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.12. Precision and Bias12.1 A bias of 102 to 105 % of acid acceptance, as com-pared to determining a
31、cid 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 highreporting by Method B.12.2 A Relative Standard Deviation of about 0.8 % can beexpected when the
32、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.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the tes
33、ting 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.D2942 02 (2018)213. Keywords13.1 acid acceptanc
34、e; halogenated organic solvents; sol-vents; total acid acceptanceASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any su
35、ch 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 be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invit
36、ed 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 theresponsible technical committee, which you may attend. If you feel that your comments have not received a
37、 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, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this
38、 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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 02 (2018)3
