1、Designation: D 2942 02Standard 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 of revision, the
2、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 method covers the
3、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 this standard to esta
4、blish 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:D 1193 Specification for Reagent Water2D 2106 Test Methods for the Determination
5、 of Amine AcidAcceptance (Alkalinity) of Halogenated Organic Solvents3E 200 Practice for Preparation, Standardization, and Stor-age of Standard and Reagent Solutions for ChemicalAnalysis33. Summary of Test Method3.1 Test Method AThe total acid acceptance is determinedby the reaction of the sample wi
6、th 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 reported as w
7、eight % 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 suitable only for
8、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 degreasers.4.
9、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 additives, ne
10、utraltype (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 accepting stab
11、i-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 abilityof a s
12、olvent 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 otherwise indicate
13、d, 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 directresponsibil
14、ity of Subcommittee D26.04 on Test Methods.Current edition approved June 10, 2002. Published August 2002. Originallypublished as D 2942 71 T. Last previous edition D 2942 96 (2000).2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 15.05.1Copyright ASTM International, 100
15、Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where such specifications are available.4Other grades 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 P
16、urity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification 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 mL of water and 200 mL of denatured ethyl alco
17、hol. 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 alcohol.6.5
18、Sodium Hydroxide, Standard Solution (0.1 N)Prepareand standardize in accordance with Practice E 200.7. 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 HCl and N
19、aOH 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 millilitres of
20、 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 to stand a
21、t 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 dry before r
22、unning 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 D 2106.9. Calculation9.1 Total Acid AcceptanceCalculate the total acid acce
23、p-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 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 mL of 1 normal so
24、lution,andW = sample used (volume in mL 3 specific gravity), g.9.2 Nonamine Acid AcceptanceCalculate the nonamineacid acceptance as equivalent 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 t
25、his 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 such as
26、 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:Equivalent Na
27、OH, 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 acid acce
28、ptance from the acidacceptor by Method A is 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 chromatography.
29、 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 acceptance4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington
30、, 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.D2942022ASTM In
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34、tandards, 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).D2942023
