1、Designation: D2942 02 (Reapproved 2013)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 Department of Defense.1. Scope1.1 This test met
3、hod 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 not
4、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 and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are gi
5、ven in Section 7.2. 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 Storageof Standard and Reagent Solutions for C
6、hemical 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 with the acidacceptor is then back-titrated
7、 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 asdensity or refractive index and the acid acce
8、ptance 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 ensurethere is no interference, particularly f
9、rom 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 process andstorage equipment used for halogen
10、ated 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 fromboth types of stabilizers. In addition, if t
11、he 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 may be used by producers and users toverif
12、y 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 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 Pipe
13、t, 10-mL and 25-mL.6. Reagents6.1 Purity of ReagentsReagent 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,1This test method is under
14、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 Feb. 1, 2013. Published March 2013. Originallyapproved in 1971. Last previous edition approved in 2008 a
15、s D2942 02(2008).DOI: 10.1520/D2942-02R13.2For 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.Copyright ASTM Inte
16、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the dete
17、rmination.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)Prepared by dissolving 1.0 g of bromophenol blue in a mixtureof 800 mLof water and 200 mLof denature
18、d 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) in isopropyl alcohol and diluting to 500 mL withisopropyl a
19、lcohol.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 the published safety procedures when handlingthe concentrated
20、 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 blue-green end point with 0.1 NNaOH solution. Record the mill
21、ilitres 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 of isopropyl alcohol. Shake the mixture thoroughly andallow
22、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 9 for calculation).NOTE 1Make sure flask and pipette are dr
23、y 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 Method D2106.9. Calculation9.1 Total Acid AcceptanceCalculate the total
24、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 = Normality of NaOH solution,0.04 = G equivalent NaOH per mLof 1 n
25、ormal 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 acid acceptance.10. Precision and Bias10.1 The precision limi
26、ts 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 also contribute acid acceptance)present by a validated method
27、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 Calculate the acid acceptance by the following for-mula:Equiva
28、lent 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 acid acceptance by Method A is notuncommon as the yield of ac
29、id 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 weight percent acid acceptor is determinedby gas chromatogra
30、phy. The precision of the acid acceptancewill be the same as the precision of the weight percent acidacceptor.13. Keywords13.1 acid acceptance; halogenated organic solvents; sol-vents; total acid acceptance3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washi
31、ngton, DC. For suggestions 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.D2942 02 (
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33、s, 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 additional s
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35、ommittee 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D2942 02 (2013)3
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